From 06389d34041e3f43f74faa0d914505b8276d72d7 Mon Sep 17 00:00:00 2001
From: Jan Henning <jh+bugzilla@buttercookie.de>
Date: Sun, 11 Mar 2018 20:01:33 +0100
Subject: [PATCH 01/50] Bug 1358598 - Show ongoing notifications even if
 they're not the "official" foreground notification. r=jchen

We can have only one "official" foreground notification that's associated with
the NotificationService to keep the OS from background-killing us at the same
time, but that doesn't mean that we should simply ignore any further ongoing
notifications possibly arriving afterwards.

MozReview-Commit-ID: L8rigs6GKzH

--HG--
extra : rebase_source : 4f8f5f76a422930c6b5e3e6d0c6e8b37d6c11123
---
 .../mozilla/gecko/notifications/NotificationClient.java   | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/mobile/android/base/java/org/mozilla/gecko/notifications/NotificationClient.java b/mobile/android/base/java/org/mozilla/gecko/notifications/NotificationClient.java
index 913b85127372..d8392a801e13 100644
--- a/mobile/android/base/java/org/mozilla/gecko/notifications/NotificationClient.java
+++ b/mobile/android/base/java/org/mozilla/gecko/notifications/NotificationClient.java
@@ -182,7 +182,7 @@ public final class NotificationClient implements NotificationListener {
         if (ongoing != isOngoing(mNotifications.get(name))) {
             // In order to change notification from ongoing to non-ongoing, or vice versa,
             // we have to remove the previous notification, because ongoing notifications
-            // use a different id value than non-ongoing notifications.
+            // might use a different id value than non-ongoing notifications.
             onNotificationClose(name);
         }
 
@@ -200,6 +200,8 @@ public final class NotificationClient implements NotificationListener {
             // Shortcut to update the current foreground notification, instead of
             // going through the service.
             mNotificationManager.notify(R.id.foregroundNotification, notification);
+        } else {
+            mNotificationManager.notify(name, 0, notification);
         }
     }
 
@@ -317,6 +319,10 @@ public final class NotificationClient implements NotificationListener {
         for (final String name : mNotifications.keySet()) {
             final Notification notification = mNotifications.get(name);
             if (isOngoing(notification)) {
+                // The same reasoning as above applies - the current foreground notification
+                // uses a special ID, so we need to close its old instantiation and then
+                // re-add it with the new ID through the NotificationService.
+                onNotificationClose(name);
                 setForegroundNotificationLocked(name, notification);
                 return;
             }

From 835d04eeac10b1652f493665b62a58892efb7e19 Mon Sep 17 00:00:00 2001
From: Paul Adenot <paul@paul.cx>
Date: Fri, 9 Mar 2018 15:22:44 +0100
Subject: [PATCH 02/50] Bug 1443224 - Throw correct exceptions when trying to
 set the channelCount, the channelCountMode and the channelInterpretation on a
 ChannelSplitterNode. r=baku

Spec: https://webaudio.github.io/web-audio-api/#dom-audionode-channelcount
Google has written a web platform test this is going to be merged soon (we
currently fail it).

MozReview-Commit-ID: 1RpASaIJrhm

--HG--
extra : rebase_source : d03145bf90796fb8b1557a4affaf75c22bee2f76
extra : source : e7b5b629fb30c4c8b8708979e926029f4e743420
---
 dom/media/webaudio/AudioNode.cpp         |  5 ++++-
 dom/media/webaudio/AudioNode.h           |  2 +-
 dom/media/webaudio/ChannelSplitterNode.h | 13 +++++++++++++
 dom/webidl/AudioNode.webidl              |  1 +
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/dom/media/webaudio/AudioNode.cpp b/dom/media/webaudio/AudioNode.cpp
index f251861cd74a..7fd85b195618 100644
--- a/dom/media/webaudio/AudioNode.cpp
+++ b/dom/media/webaudio/AudioNode.cpp
@@ -91,7 +91,10 @@ AudioNode::Initialize(const AudioNodeOptions& aOptions, ErrorResult& aRv)
   }
 
   if (aOptions.mChannelInterpretation.WasPassed()) {
-    SetChannelInterpretationValue(aOptions.mChannelInterpretation.Value());
+    SetChannelInterpretationValue(aOptions.mChannelInterpretation.Value(), aRv);
+    if (NS_WARN_IF(aRv.Failed())) {
+      return;
+    }
   }
 }
 
diff --git a/dom/media/webaudio/AudioNode.h b/dom/media/webaudio/AudioNode.h
index eb01289b19b1..f3d159b0bb53 100644
--- a/dom/media/webaudio/AudioNode.h
+++ b/dom/media/webaudio/AudioNode.h
@@ -152,7 +152,7 @@ public:
   {
     return mChannelInterpretation;
   }
-  void SetChannelInterpretationValue(ChannelInterpretation aMode)
+  virtual void SetChannelInterpretationValue(ChannelInterpretation aMode, ErrorResult& aRv)
   {
     mChannelInterpretation = aMode;
     SendChannelMixingParametersToStream();
diff --git a/dom/media/webaudio/ChannelSplitterNode.h b/dom/media/webaudio/ChannelSplitterNode.h
index 361df4b9a35b..10720f66b9c0 100644
--- a/dom/media/webaudio/ChannelSplitterNode.h
+++ b/dom/media/webaudio/ChannelSplitterNode.h
@@ -31,6 +31,19 @@ public:
     return Create(aAudioContext, aOptions, aRv);
   }
 
+  void SetChannelCount(uint32_t aChannelCount, ErrorResult& aRv)
+  {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+  }
+  void SetChannelCountModeValue(ChannelCountMode aMode, ErrorResult& aRv)
+  {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+  }
+  void SetChannelInterpretationValue(ChannelInterpretation aMode, ErrorResult& aRv)
+  {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+  }
+
   JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
   uint16_t NumberOfOutputs() const override { return mOutputCount; }
diff --git a/dom/webidl/AudioNode.webidl b/dom/webidl/AudioNode.webidl
index f8d22feaf8f1..80b33e50eeb2 100644
--- a/dom/webidl/AudioNode.webidl
+++ b/dom/webidl/AudioNode.webidl
@@ -58,6 +58,7 @@ interface AudioNode : EventTarget {
     attribute unsigned long channelCount;
     [SetterThrows]
     attribute ChannelCountMode channelCountMode;
+    [SetterThrows]
     attribute ChannelInterpretation channelInterpretation;
 
 };

From 611dd9995e794a6b2c276eac456a7f14fd9b08fc Mon Sep 17 00:00:00 2001
From: Cosmin Sabou <csabou@mozilla.com>
Date: Mon, 12 Mar 2018 11:53:54 +0200
Subject: [PATCH 03/50] Backed out changeset 7386deb98f9a (bug 1443224) for
 build bustages on dom/ChannelSplitterNode.h

---
 dom/media/webaudio/AudioNode.cpp         |  5 +----
 dom/media/webaudio/AudioNode.h           |  2 +-
 dom/media/webaudio/ChannelSplitterNode.h | 13 -------------
 dom/webidl/AudioNode.webidl              |  1 -
 4 files changed, 2 insertions(+), 19 deletions(-)

diff --git a/dom/media/webaudio/AudioNode.cpp b/dom/media/webaudio/AudioNode.cpp
index 7fd85b195618..f251861cd74a 100644
--- a/dom/media/webaudio/AudioNode.cpp
+++ b/dom/media/webaudio/AudioNode.cpp
@@ -91,10 +91,7 @@ AudioNode::Initialize(const AudioNodeOptions& aOptions, ErrorResult& aRv)
   }
 
   if (aOptions.mChannelInterpretation.WasPassed()) {
-    SetChannelInterpretationValue(aOptions.mChannelInterpretation.Value(), aRv);
-    if (NS_WARN_IF(aRv.Failed())) {
-      return;
-    }
+    SetChannelInterpretationValue(aOptions.mChannelInterpretation.Value());
   }
 }
 
diff --git a/dom/media/webaudio/AudioNode.h b/dom/media/webaudio/AudioNode.h
index f3d159b0bb53..eb01289b19b1 100644
--- a/dom/media/webaudio/AudioNode.h
+++ b/dom/media/webaudio/AudioNode.h
@@ -152,7 +152,7 @@ public:
   {
     return mChannelInterpretation;
   }
-  virtual void SetChannelInterpretationValue(ChannelInterpretation aMode, ErrorResult& aRv)
+  void SetChannelInterpretationValue(ChannelInterpretation aMode)
   {
     mChannelInterpretation = aMode;
     SendChannelMixingParametersToStream();
diff --git a/dom/media/webaudio/ChannelSplitterNode.h b/dom/media/webaudio/ChannelSplitterNode.h
index 10720f66b9c0..361df4b9a35b 100644
--- a/dom/media/webaudio/ChannelSplitterNode.h
+++ b/dom/media/webaudio/ChannelSplitterNode.h
@@ -31,19 +31,6 @@ public:
     return Create(aAudioContext, aOptions, aRv);
   }
 
-  void SetChannelCount(uint32_t aChannelCount, ErrorResult& aRv)
-  {
-    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
-  }
-  void SetChannelCountModeValue(ChannelCountMode aMode, ErrorResult& aRv)
-  {
-    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
-  }
-  void SetChannelInterpretationValue(ChannelInterpretation aMode, ErrorResult& aRv)
-  {
-    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
-  }
-
   JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
   uint16_t NumberOfOutputs() const override { return mOutputCount; }
diff --git a/dom/webidl/AudioNode.webidl b/dom/webidl/AudioNode.webidl
index 80b33e50eeb2..f8d22feaf8f1 100644
--- a/dom/webidl/AudioNode.webidl
+++ b/dom/webidl/AudioNode.webidl
@@ -58,7 +58,6 @@ interface AudioNode : EventTarget {
     attribute unsigned long channelCount;
     [SetterThrows]
     attribute ChannelCountMode channelCountMode;
-    [SetterThrows]
     attribute ChannelInterpretation channelInterpretation;
 
 };

From 2f3c2434f4da8b1a9d8eda0638cbfa9cc0542a78 Mon Sep 17 00:00:00 2001
From: Anthony Ramine <n.oxyde@gmail.com>
Date: Mon, 12 Mar 2018 04:52:02 -0400
Subject: [PATCH 04/50] servo: Merge #20275 - Finish cleaning up trait bounds
 generation in style_derive (from servo:derive-all-the-things); r=emilio

Source-Repo: https://github.com/servo/servo
Source-Revision: 9d4cdfcfc31e4d3fca16e074c7481211f880be9f

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : d9b39c62cbcc55b8ae6297c250a12cab2fb2f046
---
 servo/components/style/values/animated/mod.rs |   6 +
 servo/components/style/values/distance.rs     |   4 +
 .../style/values/generics/basic_shape.rs      |   1 +
 servo/components/style/values/generics/svg.rs |   8 +-
 servo/components/style_derive/animate.rs      |  43 ++++--
 servo/components/style_derive/cg.rs           | 141 +-----------------
 .../style_derive/compute_squared_distance.rs  | 100 ++++++++-----
 servo/components/style_derive/lib.rs          |   2 +-
 .../style_derive/to_animated_zero.rs          |  37 +++--
 9 files changed, 134 insertions(+), 208 deletions(-)

diff --git a/servo/components/style/values/animated/mod.rs b/servo/components/style/values/animated/mod.rs
index ad81a4ecc4aa..9e0653d8a008 100644
--- a/servo/components/style/values/animated/mod.rs
+++ b/servo/components/style/values/animated/mod.rs
@@ -35,6 +35,9 @@ pub mod effects;
 ///
 /// If the two values are not similar, an error is returned unless a fallback
 /// function has been specified through `#[animate(fallback)]`.
+///
+/// Trait bounds for type parameter `Foo` can be opted out of with
+/// `#[animation(no_bound(Foo))]` on the type definition.
 pub trait Animate: Sized {
     /// Animate a value towards another one, given an animation procedure.
     fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()>;
@@ -78,6 +81,9 @@ pub trait ToAnimatedValue {
 ///
 /// If a variant is annotated with `#[animation(error)]`, the corresponding
 /// `match` arm is not generated.
+///
+/// Trait bounds for type parameter `Foo` can be opted out of with
+/// `#[animation(no_bound(Foo))]` on the type definition.
 pub trait ToAnimatedZero: Sized {
     /// Returns a value that, when added with an underlying value, will produce the underlying
     /// value. This is used for SMIL animation's "by-animation" where SMIL first interpolates from
diff --git a/servo/components/style/values/distance.rs b/servo/components/style/values/distance.rs
index f17b9931ddab..5f84f17caad2 100644
--- a/servo/components/style/values/distance.rs
+++ b/servo/components/style/values/distance.rs
@@ -21,6 +21,10 @@ use std::ops::Add;
 ///
 /// If the two values are not similar, an error is returned unless a fallback
 /// function has been specified through `#[distance(fallback)]`.
+///
+/// Trait bounds for type parameter `Foo` can be opted out of with
+/// `#[animation(no_bound(Foo))]` on the type definition, trait bounds for
+/// fields can be opted into with `#[distance(field_bound)]` on the field.
 pub trait ComputeSquaredDistance {
     /// Computes the squared distance between two animatable values.
     fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()>;
diff --git a/servo/components/style/values/generics/basic_shape.rs b/servo/components/style/values/generics/basic_shape.rs
index ef9eac14ec7b..8c798b468ae9 100644
--- a/servo/components/style/values/generics/basic_shape.rs
+++ b/servo/components/style/values/generics/basic_shape.rs
@@ -43,6 +43,7 @@ pub enum ShapeBox {
 
 /// A shape source, for some reference box.
 #[allow(missing_docs)]
+#[animation(no_bound(ImageOrUrl))]
 #[derive(Animate, Clone, Debug, MallocSizeOf, PartialEq, ToComputedValue, ToCss)]
 pub enum ShapeSource<BasicShape, ReferenceBox, ImageOrUrl> {
     #[animation(error)]
diff --git a/servo/components/style/values/generics/svg.rs b/servo/components/style/values/generics/svg.rs
index 6d9928ec1af4..a856633ff474 100644
--- a/servo/components/style/values/generics/svg.rs
+++ b/servo/components/style/values/generics/svg.rs
@@ -15,6 +15,7 @@ use values::distance::{ComputeSquaredDistance, SquaredDistance};
 /// An SVG paint value
 ///
 /// <https://www.w3.org/TR/SVG2/painting.html#SpecifyingPaint>
+#[animation(no_bound(UrlPaintServer))]
 #[derive(Animate, Clone, ComputeSquaredDistance, Debug, MallocSizeOf, PartialEq)]
 #[derive(ToAnimatedValue, ToComputedValue, ToCss)]
 pub struct SVGPaint<ColorType, UrlPaintServer> {
@@ -29,6 +30,7 @@ pub struct SVGPaint<ColorType, UrlPaintServer> {
 /// Whereas the spec only allows PaintServer
 /// to have a fallback, Gecko lets the context
 /// properties have a fallback as well.
+#[animation(no_bound(UrlPaintServer))]
 #[derive(Animate, Clone, ComputeSquaredDistance, Debug, MallocSizeOf, PartialEq)]
 #[derive(ToAnimatedValue, ToAnimatedZero, ToComputedValue, ToCss)]
 pub enum SVGPaintKind<ColorType, UrlPaintServer> {
@@ -203,7 +205,11 @@ pub enum SVGLength<LengthType> {
 pub enum SVGStrokeDashArray<LengthType> {
     /// `[ <length> | <percentage> | <number> ]#`
     #[css(comma)]
-    Values(#[css(if_empty = "none", iterable)] Vec<LengthType>),
+    Values(
+        #[css(if_empty = "none", iterable)]
+        #[distance(field_bound)]
+        Vec<LengthType>,
+    ),
     /// `context-value`
     ContextValue,
 }
diff --git a/servo/components/style_derive/animate.rs b/servo/components/style_derive/animate.rs
index 912f7dbc9f2c..e54f1819c997 100644
--- a/servo/components/style_derive/animate.rs
+++ b/servo/components/style_derive/animate.rs
@@ -2,23 +2,31 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use cg::{self, WhereClause};
+use cg;
+use darling::util::IdentList;
 use quote::Tokens;
 use syn::{DeriveInput, Path};
 use synstructure::{Structure, VariantInfo};
 
-pub fn derive(input: DeriveInput) -> Tokens {
-    let name = &input.ident;
-    let trait_path = parse_quote!(values::animated::Animate);
-    let (impl_generics, ty_generics, mut where_clause) =
-        cg::trait_parts(&input, &trait_path);
+pub fn derive(mut input: DeriveInput) -> Tokens {
+    let animation_input_attrs = cg::parse_input_attrs::<AnimationInputAttrs>(&input);
+    let no_bound = animation_input_attrs.no_bound.unwrap_or_default();
+    let mut where_clause = input.generics.where_clause.take();
+    for param in input.generics.type_params() {
+        if !no_bound.contains(&param.ident) {
+            cg::add_predicate(
+                &mut where_clause,
+                parse_quote!(#param: ::values::animated::Animate),
+            );
+        }
+    }
+    input.generics.where_clause = where_clause;
 
-    let input_attrs = cg::parse_input_attrs::<AnimateInputAttrs>(&input);
     let s = Structure::new(&input);
     let mut append_error_clause = s.variants().len() > 1;
 
     let mut match_body = s.variants().iter().fold(quote!(), |body, variant| {
-        let arm = match derive_variant_arm(variant, &mut where_clause) {
+        let arm = match derive_variant_arm(variant) {
             Ok(arm) => arm,
             Err(()) => {
                 append_error_clause = true;
@@ -29,6 +37,7 @@ pub fn derive(input: DeriveInput) -> Tokens {
     });
 
     if append_error_clause {
+        let input_attrs = cg::parse_input_attrs::<AnimateInputAttrs>(&input);
         if let Some(fallback) = input_attrs.fallback {
             match_body.append_all(quote! {
                 (this, other) => #fallback(this, other, procedure)
@@ -38,6 +47,9 @@ pub fn derive(input: DeriveInput) -> Tokens {
         }
     }
 
+    let name = &input.ident;
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
     quote! {
         impl #impl_generics ::values::animated::Animate for #name #ty_generics #where_clause {
             #[allow(unused_variables, unused_imports)]
@@ -55,10 +67,7 @@ pub fn derive(input: DeriveInput) -> Tokens {
     }
 }
 
-fn derive_variant_arm(
-    variant: &VariantInfo,
-    where_clause: &mut WhereClause,
-) -> Result<Tokens, ()> {
+fn derive_variant_arm(variant: &VariantInfo) -> Result<Tokens, ()> {
     let variant_attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(&variant.ast());
     if variant_attrs.error {
         return Err(());
@@ -78,7 +87,6 @@ fn derive_variant_arm(
                 let #result = ::std::clone::Clone::clone(#this);
             }
         } else {
-            where_clause.add_trait_bound(&result.ast().ty);
             quote! {
                 let #result =
                     ::values::animated::Animate::animate(#this, #other, procedure)?;
@@ -99,10 +107,19 @@ struct AnimateInputAttrs {
     fallback: Option<Path>,
 }
 
+#[darling(attributes(animation), default)]
+#[derive(Default, FromDeriveInput)]
+pub struct AnimationInputAttrs {
+    pub no_bound: Option<IdentList>,
+}
+
 #[darling(attributes(animation), default)]
 #[derive(Default, FromVariant)]
 pub struct AnimationVariantAttrs {
     pub error: bool,
+    // Only here because of structs, where the struct definition acts as a
+    // variant itself.
+    pub no_bound: Option<IdentList>,
 }
 
 #[darling(attributes(animation), default)]
diff --git a/servo/components/style_derive/cg.rs b/servo/components/style_derive/cg.rs
index 694973103cea..ff391c791804 100644
--- a/servo/components/style_derive/cg.rs
+++ b/servo/components/style_derive/cg.rs
@@ -3,83 +3,14 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use darling::{FromDeriveInput, FromField, FromVariant};
-use quote::{ToTokens, Tokens};
-use std::collections::HashSet;
+use quote::Tokens;
 use syn::{self, AngleBracketedGenericArguments, Binding, DeriveInput, Field};
-use syn::{GenericArgument, GenericParam, Ident, ImplGenerics, Path};
-use syn::{PathArguments, PathSegment, QSelf, Type, TypeArray, TypeGenerics};
+use syn::{GenericArgument, GenericParam, Ident, Path};
+use syn::{PathArguments, PathSegment, QSelf, Type, TypeArray};
 use syn::{TypeParam, TypeParen, TypePath, TypeSlice, TypeTuple};
 use syn::{Variant, WherePredicate};
-use syn::visit::{self, Visit};
 use synstructure::{self, BindingInfo, BindStyle, VariantAst, VariantInfo};
 
-pub struct WhereClause<'input, 'path> {
-    pub inner: Option<syn::WhereClause>,
-    pub params: Vec<&'input TypeParam>,
-    trait_path: &'path Path,
-    trait_output: Option<Ident>,
-    bounded_types: HashSet<Type>,
-}
-
-impl<'input, 'path> ToTokens for WhereClause<'input, 'path> {
-    fn to_tokens(&self, tokens: &mut Tokens) {
-        self.inner.to_tokens(tokens);
-    }
-}
-
-impl<'input, 'path> WhereClause<'input, 'path> {
-    pub fn add_trait_bound(&mut self, ty: &Type) {
-        let trait_path = self.trait_path;
-        let mut found = self.trait_output.map(|_| HashSet::new());
-        if self.bounded_types.contains(&ty) {
-            return;
-        }
-        if !is_parameterized(&ty, &self.params, found.as_mut()) {
-            return;
-        }
-        self.bounded_types.insert(ty.clone());
-
-        let output = if let Some(output) = self.trait_output {
-            output
-        } else {
-            add_predicate(&mut self.inner, where_predicate(ty.clone(), trait_path, None));
-            return;
-        };
-
-        if let Type::Path(syn::TypePath { ref path, .. }) = *ty {
-            if path_to_ident(path).is_some() {
-                add_predicate(&mut self.inner, where_predicate(ty.clone(), trait_path, None));
-                return;
-            }
-        }
-
-        let output_type = map_type_params(ty, &self.params, &mut |ident| {
-            parse_quote!(<#ident as ::#trait_path>::#output)
-        });
-
-        let pred = where_predicate(
-            ty.clone(),
-            trait_path,
-            Some((output, output_type)),
-        );
-
-        add_predicate(&mut self.inner, pred);
-
-        if let Some(found) = found {
-            for ident in found {
-                let ty = Type::Path(syn::TypePath { qself: None, path: ident.into() });
-                if !self.bounded_types.contains(&ty) {
-                    self.bounded_types.insert(ty.clone());
-                    add_predicate(
-                        &mut self.inner,
-                        where_predicate(ty, trait_path, None),
-                    );
-                };
-            }
-        }
-    }
-}
-
 pub fn add_predicate(
     where_clause: &mut Option<syn::WhereClause>,
     pred: WherePredicate,
@@ -139,36 +70,6 @@ pub fn fmap_trait_output(
     segment.into()
 }
 
-pub fn is_parameterized(
-    ty: &Type,
-    params: &[&TypeParam],
-    found: Option<&mut HashSet<Ident>>,
-) -> bool {
-    struct IsParameterized<'a, 'b> {
-        params: &'a [&'a TypeParam],
-        has_free: bool,
-        found: Option<&'b mut HashSet<Ident>>,
-    }
-
-    impl<'a, 'b, 'ast> Visit<'ast> for IsParameterized<'a, 'b> {
-        fn visit_path(&mut self, path: &'ast Path) {
-            if let Some(ident) = path_to_ident(path) {
-                if self.params.iter().any(|param| param.ident == ident) {
-                    self.has_free = true;
-                    if let Some(ref mut found) = self.found {
-                        found.insert(ident.clone());
-                    }
-                }
-            }
-            visit::visit_path(self, path);
-        }
-    }
-
-    let mut visitor = IsParameterized { params, has_free: false, found };
-    visitor.visit_type(ty);
-    visitor.has_free
-}
-
 pub fn map_type_params<F>(ty: &Type, params: &[&TypeParam], f: &mut F) -> Type
 where
     F: FnMut(&Ident) -> Type,
@@ -314,33 +215,6 @@ pub fn ref_pattern<'a>(
     (v.pat(), v.bindings().iter().cloned().collect())
 }
 
-pub fn trait_parts<'input, 'path>(
-    input: &'input DeriveInput,
-    trait_path: &'path Path,
-) -> (ImplGenerics<'input>, TypeGenerics<'input>, WhereClause<'input, 'path>) {
-    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
-    let where_clause = WhereClause {
-        inner: where_clause.cloned(),
-        params: input.generics.type_params().into_iter().collect::<Vec<&TypeParam>>(),
-        trait_path,
-        trait_output: None,
-        bounded_types: HashSet::new()
-    };
-    (impl_generics, ty_generics, where_clause)
-}
-
-fn trait_ref(path: &Path, output: Option<(Ident, Type)>) -> Path {
-    let segments = path.segments.iter().collect::<Vec<&PathSegment>>();
-    let (name, parent) = segments.split_last().unwrap();
-
-    let last_segment: PathSegment = if let Some((param, ty)) = output {
-        parse_quote!(#name<#param = #ty>)
-    } else {
-        parse_quote!(#name)
-    };
-    parse_quote!(::#(#parent::)*#last_segment)
-}
-
 pub fn value<'a>(
     variant: &'a VariantInfo,
     prefix: &str,
@@ -351,15 +225,6 @@ pub fn value<'a>(
     (v.pat(), v.bindings().iter().cloned().collect())
 }
 
-pub fn where_predicate(
-    bounded_ty: Type,
-    trait_path: &Path,
-    trait_output: Option<(Ident, Type)>,
-) -> WherePredicate {
-    let trait_ref = trait_ref(trait_path, trait_output);
-    parse_quote!(#bounded_ty: #trait_ref)
-}
-
 /// Transforms "FooBar" to "foo-bar".
 ///
 /// If the first Camel segment is "Moz", "Webkit", or "Servo", the result string
diff --git a/servo/components/style_derive/compute_squared_distance.rs b/servo/components/style_derive/compute_squared_distance.rs
index 6254340e358f..07408bbcddb5 100644
--- a/servo/components/style_derive/compute_squared_distance.rs
+++ b/servo/components/style_derive/compute_squared_distance.rs
@@ -2,52 +2,71 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use animate::AnimationVariantAttrs;
+use animate::{AnimationInputAttrs, AnimationVariantAttrs};
 use cg;
 use quote::Tokens;
 use syn::{DeriveInput, Path};
 use synstructure;
 
-pub fn derive(input: DeriveInput) -> Tokens {
-    let name = &input.ident;
-    let trait_path = parse_quote!(values::distance::ComputeSquaredDistance);
-    let (impl_generics, ty_generics, mut where_clause) =
-        cg::trait_parts(&input, &trait_path);
-
-    let input_attrs = cg::parse_input_attrs::<DistanceInputAttrs>(&input);
-    let s = synstructure::Structure::new(&input);
-    let mut append_error_clause = s.variants().len() > 1;
-
-    let mut match_body = s.variants().iter().fold(quote!(), |body, variant| {
-        let attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(&variant.ast());
-        if attrs.error {
-            append_error_clause = true;
-            return body;
+pub fn derive(mut input: DeriveInput) -> Tokens {
+    let animation_input_attrs = cg::parse_input_attrs::<AnimationInputAttrs>(&input);
+    let no_bound = animation_input_attrs.no_bound.unwrap_or_default();
+    let mut where_clause = input.generics.where_clause.take();
+    for param in input.generics.type_params() {
+        if !no_bound.contains(&param.ident) {
+            cg::add_predicate(
+                &mut where_clause,
+                parse_quote!(#param: ::values::distance::ComputeSquaredDistance),
+            );
         }
+    }
 
-        let (this_pattern, this_info) = cg::ref_pattern(&variant, "this");
-        let (other_pattern, other_info) = cg::ref_pattern(&variant, "other");
-        let sum = if this_info.is_empty() {
-            quote! { ::values::distance::SquaredDistance::from_sqrt(0.) }
-        } else {
-            let mut sum = quote!();
-            sum.append_separated(this_info.iter().zip(&other_info).map(|(this, other)| {
-                where_clause.add_trait_bound(&this.ast().ty);
-                quote! {
-                    ::values::distance::ComputeSquaredDistance::compute_squared_distance(#this, #other)?
-                }
-            }), quote!(+));
-            sum
-        };
-        quote! {
-            #body
-            (&#this_pattern, &#other_pattern) => {
-                Ok(#sum)
+    let (mut match_body, append_error_clause) = {
+        let s = synstructure::Structure::new(&input);
+        let mut append_error_clause = s.variants().len() > 1;
+
+        let match_body = s.variants().iter().fold(quote!(), |body, variant| {
+            let attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(&variant.ast());
+            if attrs.error {
+                append_error_clause = true;
+                return body;
             }
-        }
-    });
+
+            let (this_pattern, this_info) = cg::ref_pattern(&variant, "this");
+            let (other_pattern, other_info) = cg::ref_pattern(&variant, "other");
+            let sum = if this_info.is_empty() {
+                quote! { ::values::distance::SquaredDistance::from_sqrt(0.) }
+            } else {
+                let mut sum = quote!();
+                sum.append_separated(this_info.iter().zip(&other_info).map(|(this, other)| {
+                    let field_attrs = cg::parse_field_attrs::<DistanceFieldAttrs>(&this.ast());
+                    if field_attrs.field_bound {
+                        let ty = &this.ast().ty;
+                        cg::add_predicate(
+                            &mut where_clause,
+                            parse_quote!(#ty: ::values::distance::ComputeSquaredDistance),
+                        );
+                    }
+                    quote! {
+                        ::values::distance::ComputeSquaredDistance::compute_squared_distance(#this, #other)?
+                    }
+                }), quote!(+));
+                sum
+            };
+            quote! {
+                #body
+                (&#this_pattern, &#other_pattern) => {
+                    Ok(#sum)
+                }
+            }
+        });
+
+        (match_body, append_error_clause)
+    };
+    input.generics.where_clause = where_clause;
 
     if append_error_clause {
+        let input_attrs = cg::parse_input_attrs::<DistanceInputAttrs>(&input);
         if let Some(fallback) = input_attrs.fallback {
             match_body.append_all(quote! {
                 (this, other) => #fallback(this, other)
@@ -57,6 +76,9 @@ pub fn derive(input: DeriveInput) -> Tokens {
         }
     }
 
+    let name = &input.ident;
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
+
     quote! {
         impl #impl_generics ::values::distance::ComputeSquaredDistance for #name #ty_generics #where_clause {
             #[allow(unused_variables, unused_imports)]
@@ -78,3 +100,9 @@ pub fn derive(input: DeriveInput) -> Tokens {
 struct DistanceInputAttrs {
     fallback: Option<Path>,
 }
+
+#[darling(attributes(distance), default)]
+#[derive(Default, FromField)]
+struct DistanceFieldAttrs {
+    field_bound: bool,
+}
diff --git a/servo/components/style_derive/lib.rs b/servo/components/style_derive/lib.rs
index e414a3bd3f21..e9d799fe9a95 100644
--- a/servo/components/style_derive/lib.rs
+++ b/servo/components/style_derive/lib.rs
@@ -45,7 +45,7 @@ pub fn derive_parse(stream: TokenStream) -> TokenStream {
     parse::derive(input).into()
 }
 
-#[proc_macro_derive(ToAnimatedZero, attributes(animation))]
+#[proc_macro_derive(ToAnimatedZero, attributes(animation, zero))]
 pub fn derive_to_animated_zero(stream: TokenStream) -> TokenStream {
     let input = syn::parse(stream).unwrap();
     to_animated_zero::derive(input).into()
diff --git a/servo/components/style_derive/to_animated_zero.rs b/servo/components/style_derive/to_animated_zero.rs
index 8094e46874d7..9ee786f7ec87 100644
--- a/servo/components/style_derive/to_animated_zero.rs
+++ b/servo/components/style_derive/to_animated_zero.rs
@@ -2,20 +2,26 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use animate::{AnimationVariantAttrs, AnimationFieldAttrs};
+use animate::{AnimationFieldAttrs, AnimationInputAttrs, AnimationVariantAttrs};
 use cg;
 use quote;
 use syn;
 use synstructure;
 
-pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
-    let name = &input.ident;
-    let trait_path = parse_quote!(values::animated::ToAnimatedZero);
-    let (impl_generics, ty_generics, mut where_clause) =
-        cg::trait_parts(&input, &trait_path);
+pub fn derive(mut input: syn::DeriveInput) -> quote::Tokens {
+    let animation_input_attrs = cg::parse_input_attrs::<AnimationInputAttrs>(&input);
+    let no_bound = animation_input_attrs.no_bound.unwrap_or_default();
+    let mut where_clause = input.generics.where_clause.take();
+    for param in input.generics.type_params() {
+        if !no_bound.contains(&param.ident) {
+            cg::add_predicate(
+                &mut where_clause,
+                parse_quote!(#param: ::values::animated::ToAnimatedZero),
+            );
+        }
+    }
 
-    let s = synstructure::Structure::new(&input);
-    let to_body = s.each_variant(|variant| {
+    let to_body = synstructure::Structure::new(&input).each_variant(|variant| {
         let attrs = cg::parse_variant_attrs::<AnimationVariantAttrs>(&variant.ast());
         if attrs.error {
             return Some(quote! { Err(()) });
@@ -26,21 +32,10 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
         computations.append_all(bindings_pairs.map(|(binding, mapped_binding)| {
             let field_attrs = cg::parse_field_attrs::<AnimationFieldAttrs>(&binding.ast());
             if field_attrs.constant {
-                if cg::is_parameterized(&binding.ast().ty, &where_clause.params, None) {
-                    cg::add_predicate(
-                        &mut where_clause.inner,
-                        cg::where_predicate(
-                            binding.ast().ty.clone(),
-                            &parse_quote!(std::clone::Clone),
-                            None,
-                        ),
-                    );
-                }
                 quote! {
                     let #mapped_binding = ::std::clone::Clone::clone(#binding);
                 }
             } else {
-                where_clause.add_trait_bound(&binding.ast().ty);
                 quote! {
                     let #mapped_binding =
                         ::values::animated::ToAnimatedZero::to_animated_zero(#binding)?;
@@ -50,6 +45,10 @@ pub fn derive(input: syn::DeriveInput) -> quote::Tokens {
         computations.append_all(quote! { Ok(#mapped) });
         Some(computations)
     });
+    input.generics.where_clause = where_clause;
+
+    let name = &input.ident;
+    let (impl_generics, ty_generics, where_clause) = input.generics.split_for_impl();
 
     quote! {
         impl #impl_generics ::values::animated::ToAnimatedZero for #name #ty_generics #where_clause {

From ae32006cefa5a799aae54d35fa7dbbfb77a4bfd7 Mon Sep 17 00:00:00 2001
From: Jan Odvarko <odvarko@gmail.com>
Date: Mon, 12 Mar 2018 08:10:39 +0100
Subject: [PATCH 05/50] Bug 1223726 - Customize response body interception;
 r=ochameau * Introduce pref for custom response body limit * Introduce pref
 for saving request/response bodies

MozReview-Commit-ID: 7DrAU1did1a

--HG--
extra : rebase_source : c6328f3ce8552b49caaca09489cf10c0685af58b
---
 .../netmonitor/test/browser_net_truncate.js   |  4 ++--
 devtools/client/preferences/devtools.js       |  3 +++
 .../webconsole/webconsole-connection-proxy.js |  8 +++++++-
 devtools/shared/webconsole/network-monitor.js | 19 ++++++++++---------
 modules/libpref/init/all.js                   |  6 ++++++
 5 files changed, 28 insertions(+), 12 deletions(-)

diff --git a/devtools/client/netmonitor/test/browser_net_truncate.js b/devtools/client/netmonitor/test/browser_net_truncate.js
index 34cca60a69fa..83245b27d219 100644
--- a/devtools/client/netmonitor/test/browser_net_truncate.js
+++ b/devtools/client/netmonitor/test/browser_net_truncate.js
@@ -8,8 +8,8 @@
  */
 
 add_task(async function () {
-  let { RESPONSE_BODY_LIMIT } = require("devtools/shared/webconsole/network-monitor");
-  let URL = EXAMPLE_URL + "sjs_truncate-test-server.sjs?limit=" + RESPONSE_BODY_LIMIT;
+  let limit = Services.prefs.getIntPref("devtools.netmonitor.responseBodyLimit");
+  let URL = EXAMPLE_URL + "sjs_truncate-test-server.sjs?limit=" + limit;
   let { monitor, tab } = await initNetMonitor(URL);
 
   info("Starting test... ");
diff --git a/devtools/client/preferences/devtools.js b/devtools/client/preferences/devtools.js
index fa800694e2cb..d74aa32f33cc 100644
--- a/devtools/client/preferences/devtools.js
+++ b/devtools/client/preferences/devtools.js
@@ -165,6 +165,9 @@ pref("devtools.netmonitor.visibleColumns",
   "[\"status\",\"method\",\"file\",\"domain\",\"cause\",\"type\",\"transferred\",\"contentSize\",\"waterfall\"]"
 );
 
+// Save request/response bodies yes/no.
+pref("devtools.netmonitor.saveRequestAndResponseBodies", true);
+
 // The default Network monitor HAR export setting
 pref("devtools.netmonitor.har.defaultLogDir", "");
 pref("devtools.netmonitor.har.defaultFileName", "Archive %date");
diff --git a/devtools/client/webconsole/webconsole-connection-proxy.js b/devtools/client/webconsole/webconsole-connection-proxy.js
index cec613095d5f..f69cf66c64f8 100644
--- a/devtools/client/webconsole/webconsole-connection-proxy.js
+++ b/devtools/client/webconsole/webconsole-connection-proxy.js
@@ -208,9 +208,15 @@ WebConsoleConnectionProxy.prototype = {
     this.webConsoleClient = webConsoleClient;
     this._hasNativeConsoleAPI = response.nativeConsoleAPI;
 
+    let saveBodies = Services.prefs.getBoolPref(
+      "devtools.netmonitor.saveRequestAndResponseBodies");
+
     // There is no way to view response bodies from the Browser Console, so do
     // not waste the memory.
-    let saveBodies = !this.webConsoleFrame.isBrowserConsole;
+    if (this.webConsoleFrame.isBrowserConsole) {
+      saveBodies = false;
+    }
+
     this.webConsoleFrame.setSaveRequestAndResponseBodies(saveBodies);
 
     this.webConsoleClient.on("networkEvent", this._onNetworkEvent);
diff --git a/devtools/shared/webconsole/network-monitor.js b/devtools/shared/webconsole/network-monitor.js
index 125ea34b3431..2efc5f9354d4 100644
--- a/devtools/shared/webconsole/network-monitor.js
+++ b/devtools/shared/webconsole/network-monitor.js
@@ -35,11 +35,6 @@ const HTTP_FOUND = 302;
 const HTTP_SEE_OTHER = 303;
 const HTTP_TEMPORARY_REDIRECT = 307;
 
-// The maximum number of bytes a NetworkResponseListener can hold: 1 MB
-const RESPONSE_BODY_LIMIT = 1048576;
-// Exported for testing.
-exports.RESPONSE_BODY_LIMIT = RESPONSE_BODY_LIMIT;
-
 /**
  * Check if a given network request should be logged by a network monitor
  * based on the specified filters.
@@ -279,13 +274,16 @@ function NetworkResponseListener(owner, httpActivity) {
   this.receivedData = "";
   this.httpActivity = httpActivity;
   this.bodySize = 0;
-  // Indicates if the response had a size greater than RESPONSE_BODY_LIMIT.
+  // Indicates if the response had a size greater than response body limit.
   this.truncated = false;
   // Note that this is really only needed for the non-e10s case.
   // See bug 1309523.
   let channel = this.httpActivity.channel;
   this._wrappedNotificationCallbacks = channel.notificationCallbacks;
   channel.notificationCallbacks = this;
+
+  this.responseBodyLimit = Services.prefs.getIntPref(
+    "devtools.netmonitor.responseBodyLimit");
 }
 
 NetworkResponseListener.prototype = {
@@ -397,7 +395,7 @@ NetworkResponseListener.prototype = {
   /**
    * Stores the received data, if request/response body logging is enabled. It
    * also does limit the number of stored bytes, based on the
-   * RESPONSE_BODY_LIMIT constant.
+   * `devtools.netmonitor.responseBodyLimit` pref.
    *
    * Learn more about nsIStreamListener at:
    * https://developer.mozilla.org/en/XPCOM_Interface_Reference/nsIStreamListener
@@ -415,10 +413,13 @@ NetworkResponseListener.prototype = {
     this.bodySize += count;
 
     if (!this.httpActivity.discardResponseBody) {
-      if (this.receivedData.length < RESPONSE_BODY_LIMIT) {
+      let limit = Services.prefs.getIntPref("devtools.netmonitor.responseBodyLimit");
+      if (this.receivedData.length < limit || limit == 0) {
         this.receivedData +=
           NetworkHelper.convertToUnicode(data, request.contentCharset);
-      } else {
+      }
+      if (this.receivedData.length > limit && limit > 0) {
+        this.receivedData = this.receivedData.substr(0, limit);
         this.truncated = true;
       }
     }
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index b4be2188f459..c2171e2c53c2 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1113,6 +1113,12 @@ pref("devtools.debugger.force-local", true);
 // Block tools from seeing / interacting with certified apps
 pref("devtools.debugger.forbid-certified-apps", true);
 
+// Limit for intercepted response bodies (1 MB)
+// Possible values:
+// 0 => the response body has no limit
+// n => represents max number of bytes stored
+pref("devtools.netmonitor.responseBodyLimit", 1048576);
+
 // DevTools default color unit
 pref("devtools.defaultColorUnit", "authored");
 

From 0a7ee875450f4d4becd2ec83adb54845f5ef84ae Mon Sep 17 00:00:00 2001
From: Jan Odvarko <odvarko@gmail.com>
Date: Mon, 12 Mar 2018 08:10:40 +0100
Subject: [PATCH 06/50] Bug 1223726 - Update tests; r=ochameau

MozReview-Commit-ID: 3iokswH0ybw

--HG--
extra : rebase_source : b12ca75d51a36b7554eed114bec39d30e9295a48
---
 .../test/browser_net_har_copy_all_as_har.js   | 63 ++++++++++++-------
 1 file changed, 42 insertions(+), 21 deletions(-)

diff --git a/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js b/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js
index 80b2f97b34f1..8a3621b1d3aa 100644
--- a/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js
+++ b/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js
@@ -10,30 +10,12 @@ add_task(async function () {
   // Disable tcp fast open, because it is setting a response header indicator
   // (bug 1352274). TCP Fast Open is not present on all platforms therefore the
   // number of response headers will vary depending on the platform.
-  Services.prefs.setBoolPref("network.tcp.tcp_fastopen_enable", false);
+  await pushPref("network.tcp.tcp_fastopen_enable", false);
   let { tab, monitor } = await initNetMonitor(SIMPLE_URL);
 
-  info("Starting test... ");
+  info("Starting test...");
 
-  let { connector, store, windowRequire } = monitor.panelWin;
-  let Actions = windowRequire("devtools/client/netmonitor/src/actions/index");
-  let RequestListContextMenu = windowRequire(
-    "devtools/client/netmonitor/src/widgets/RequestListContextMenu");
-  let { getSortedRequests } = windowRequire(
-    "devtools/client/netmonitor/src/selectors/index");
-
-  store.dispatch(Actions.batchEnable(false));
-
-  let wait = waitForNetworkEvents(monitor, 1);
-  tab.linkedBrowser.reload();
-  await wait;
-
-  let contextMenu = new RequestListContextMenu({ connector });
-
-  await contextMenu.copyAllAsHar(getSortedRequests(store.getState()));
-
-  let jsonString = SpecialPowers.getClipboardData("text/unicode");
-  let har = JSON.parse(jsonString);
+  let har = await reloadAndCopyAllAsHar(tab, monitor);
 
   // Check out HAR log
   isnot(har.log, null, "The HAR log must exist");
@@ -60,5 +42,44 @@ add_task(async function () {
     "Check response body");
   isnot(entry.timings, undefined, "Check timings");
 
+  // Test response body limit (non zero).
+  await pushPref("devtools.netmonitor.responseBodyLimit", 10);
+  har = await reloadAndCopyAllAsHar(tab, monitor);
+  entry = har.log.entries[0];
+  is(entry.response.content.text.length, 10, // eslint-disable-line
+    "Response body must be truncated");
+
+  // Test response body limit (zero).
+  await pushPref("devtools.netmonitor.responseBodyLimit", 0);
+  har = await reloadAndCopyAllAsHar(tab, monitor);
+  entry = har.log.entries[0];
+  is(entry.response.content.text.length, 465, // eslint-disable-line
+    "Response body must not be truncated");
+
   return teardown(monitor);
 });
+
+/**
+ * Reload the page and copy all as HAR.
+ */
+async function reloadAndCopyAllAsHar(tab, monitor) {
+  let { connector, store, windowRequire } = monitor.panelWin;
+  let Actions = windowRequire("devtools/client/netmonitor/src/actions/index");
+  let RequestListContextMenu = windowRequire(
+    "devtools/client/netmonitor/src/widgets/RequestListContextMenu");
+  let { getSortedRequests } = windowRequire(
+    "devtools/client/netmonitor/src/selectors/index");
+
+  store.dispatch(Actions.batchEnable(false));
+
+  let wait = waitForNetworkEvents(monitor, 1);
+  tab.linkedBrowser.reload();
+  await wait;
+
+  let contextMenu = new RequestListContextMenu({ connector });
+
+  await contextMenu.copyAllAsHar(getSortedRequests(store.getState()));
+
+  let jsonString = SpecialPowers.getClipboardData("text/unicode");
+  return JSON.parse(jsonString);
+}

From cf3fc487d37571bd5e829a12f78d48235c1aab0d Mon Sep 17 00:00:00 2001
From: Jan Odvarko <odvarko@gmail.com>
Date: Mon, 12 Mar 2018 10:59:21 +0100
Subject: [PATCH 07/50] Bug 1223726 - Update tests; r=jdescottes

MozReview-Commit-ID: 6FR7W58WRg0

--HG--
extra : rebase_source : db75d8db16aa4358d515f885cf0f54aff5ec28fe
---
 .../test/browser_styleeditor_fetch-from-netmonitor.js         | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js b/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
index 0689e68a45ea..7a643e65a0c0 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
@@ -34,6 +34,10 @@ add_task(function* () {
   yield ui.selectStyleSheet(ui.editors[1].styleSheet);
   yield ui.editors[1].getSourceEditor();
 
+  // Wait till there is 5 requests in Netmonitor store.
+  // (i.e. the Styleeditor panel performed one request).
+  yield waitUntil(() => getSortedRequests(store.getState()).length == 5);
+
   info("Checking Netmonitor contents.");
   let shortRequests = [];
   let longRequests = [];

From 8b3e103464c100143c2556ab4f06e2e61a8d8724 Mon Sep 17 00:00:00 2001
From: Austin Lasher <austin@lasher.email>
Date: Tue, 20 Feb 2018 23:31:09 -0500
Subject: [PATCH 08/50] Bug 1421563 - Remove TryOptimizeToImageLayer
 declaration; r=kechen,mattwoodrow

TryOptimizeToImageLayer was renamed/repurposed in c0654f3b986d, but
the old declaration was never removed.

MozReview-Commit-ID: 52JJofv3u3t

--HG--
extra : rebase_source : 959bee3f9c1bbab9f4b456fcfd4d8fe1ff1655f7
---
 layout/painting/nsDisplayList.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/layout/painting/nsDisplayList.h b/layout/painting/nsDisplayList.h
index dc3af5d26558..2b86db7894c1 100644
--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -3998,7 +3998,6 @@ protected:
   typedef class mozilla::layers::ImageLayer ImageLayer;
 
   bool CanBuildWebRenderDisplayItems(LayerManager* aManager);
-  bool TryOptimizeToImageLayer(LayerManager* aManager, nsDisplayListBuilder* aBuilder);
   nsRect GetBoundsInternal(nsDisplayListBuilder* aBuilder,
                            nsIFrame* aFrameForBounds = nullptr);
 

From e7bd29e8906c00e1c4c06d4dea60f9db61b8cc93 Mon Sep 17 00:00:00 2001
From: Ian Moody <moz-ian@perix.co.uk>
Date: Thu, 8 Feb 2018 19:03:31 +0000
Subject: [PATCH 09/50] Bug 1432636 - Switch XMLPrettyPrint to use HTML
 <details> instead of click handlers for expandables. r=ntim,peterv

Also remove duplicate import from the XMLMonoPrint sheet (unnamed default sheets
stay applied when switching to alternates, only named are unapplied).

Additionally fix some regressions from bug 379683:
* top-level collapsed and uncollapsible elements weren't monospaced in monospace
  style.
* top-level uncollapsible elements weren't indented.
* there was an extra space between PIs and their expander control.

Based on prototype by bgrins.

MozReview-Commit-ID: 2Pikm41FMWY

--HG--
extra : rebase_source : a8fb7dd9f40a267e93d50342c51728dcc98c4918
---
 dom/base/test/file_bug590812-ref.xhtml |  4 +-
 dom/xml/resources/XMLMonoPrint.css     |  5 +-
 dom/xml/resources/XMLPrettyPrint.css   | 34 +++++++-----
 dom/xml/resources/XMLPrettyPrint.xml   | 20 +------
 dom/xml/resources/XMLPrettyPrint.xsl   | 74 +++++++++++++-------------
 5 files changed, 63 insertions(+), 74 deletions(-)

diff --git a/dom/base/test/file_bug590812-ref.xhtml b/dom/base/test/file_bug590812-ref.xhtml
index dd0948b08aea..7309425fb4b8 100644
--- a/dom/base/test/file_bug590812-ref.xhtml
+++ b/dom/base/test/file_bug590812-ref.xhtml
@@ -1,3 +1,3 @@
-<out><div id="top" class="highlight" xmlns="http://www.w3.org/1999/xhtml"><link href="chrome://global/content/xml/XMLPrettyPrint.css" type="text/css" rel="stylesheet"/><div id="header"><p>
+<out><div id="top" xmlns="http://www.w3.org/1999/xhtml"><link href="chrome://global/content/xml/XMLPrettyPrint.css" type="text/css" rel="stylesheet"/><div id="header"><p>
         This XML file does not appear to have any style information associated with it. The document tree is shown below.
-      </p></div><div>&lt;<span class="start-tag">out</span>&gt;<span class="text">Here be sea hags</span>&lt;/<span class="end-tag">out</span>&gt;</div></div></out>
+      </p></div><main id="tree" class="highlight"><div>&lt;<span class="start-tag">out</span>&gt;<span class="text">Here be sea hags</span>&lt;/<span class="end-tag">out</span>&gt;</div></main></div></out>
diff --git a/dom/xml/resources/XMLMonoPrint.css b/dom/xml/resources/XMLMonoPrint.css
index 598daba22b93..95875d0e5aa2 100644
--- a/dom/xml/resources/XMLMonoPrint.css
+++ b/dom/xml/resources/XMLMonoPrint.css
@@ -3,9 +3,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-@import url("chrome://global/content/xml/XMLPrettyPrint.css");
-
-#top > .expander-open {
+#tree,
+.expandable-opening::-moz-list-bullet {
   font-family: monospace;
   white-space: pre;
 }
diff --git a/dom/xml/resources/XMLPrettyPrint.css b/dom/xml/resources/XMLPrettyPrint.css
index 13bb61e71532..50abee7d89ae 100644
--- a/dom/xml/resources/XMLPrettyPrint.css
+++ b/dom/xml/resources/XMLPrettyPrint.css
@@ -12,30 +12,36 @@
   margin-bottom: 1em;
 }
 
-.expander-content {
-  padding-left: 1em;
+#tree,
+.expandable-children {
+  margin-inline-start: 1em;
 }
 
-.expander {
-  cursor: pointer;
-  -moz-user-select: none;
-  text-align: center;
-  vertical-align: top;
-  width: 1em;
+.expandable-body {
   display: inline-block;
-  margin-left: -1em;
 }
 
-#top > .expander-open, #top > .expander-closed {
-  margin-left: 1em;
+.expandable-body[open] {
+  display: block;
 }
 
-.expander-closed > .expander-content {
-  display: none;
+.expandable-opening {
+  list-style: '+' outside;
+}
+
+[open] > .expandable-opening {
+  list-style-type: '−';
+}
+
+.expandable-opening::-moz-list-bullet {
+  cursor: pointer;
+  padding-inline-end: 2px;
+  /* Don't want to inherit the styling from pi and comment elements */
+  color: initial;
+  font: initial;
 }
 
 .comment {
   font-family: monospace;
   white-space: pre;
 }
-
diff --git a/dom/xml/resources/XMLPrettyPrint.xml b/dom/xml/resources/XMLPrettyPrint.xml
index 522d37210ac4..9df399cb58c0 100644
--- a/dom/xml/resources/XMLPrettyPrint.xml
+++ b/dom/xml/resources/XMLPrettyPrint.xml
@@ -8,29 +8,11 @@
 
   <binding id="prettyprint" bindToUntrustedContent="true">
 
-    <content><html:div id='top' class="highlight"/>
+    <content><html:div id="top"/>
       <html:span style="display: none;"><children/></html:span>
     </content>
 
     <handlers>
-      <handler event="click" button="0">
-      <![CDATA[
-        try {
-          var par = event.originalTarget;
-          if (par.nodeName == 'div' && par.className == 'expander') {
-            if (par.parentNode.className == 'expander-closed') {
-              par.parentNode.className = 'expander-open';
-              event.originalTarget.firstChild.data = '\u2212';
-            }
-            else {
-              par.parentNode.className = 'expander-closed';
-              event.originalTarget.firstChild.data = '+';
-            }
-          }
-        } catch (e) {
-        }
-      ]]>
-      </handler>
       <handler event="prettyprint-dom-created" allowuntrusted="false">
         <![CDATA[
           document.getAnonymousNodes(this).item(0).appendChild(event.detail);
diff --git a/dom/xml/resources/XMLPrettyPrint.xsl b/dom/xml/resources/XMLPrettyPrint.xsl
index bdd9b728792c..9e8580f10f85 100644
--- a/dom/xml/resources/XMLPrettyPrint.xsl
+++ b/dom/xml/resources/XMLPrettyPrint.xsl
@@ -24,7 +24,9 @@
         &xml.nostylesheet;
       </p>
     </div>
-    <xsl:apply-templates/>
+    <main id="tree" class="highlight">
+      <xsl:apply-templates/>
+    </main>
   </xsl:template>
 
   <xsl:template match="*">
@@ -52,19 +54,23 @@
   </xsl:template>
 
   <xsl:template match="*[* or processing-instruction() or comment() or string-length(.) &gt; 50]">
-    <div class="expander-open">
-      <xsl:call-template name="expander"/>
+    <div>
+      <details open="" class="expandable-body">
+        <summary class="expandable-opening">
+          <xsl:text>&lt;</xsl:text>
+          <span class="start-tag"><xsl:value-of select="name(.)"/></span>
+          <xsl:apply-templates select="@*"/>
+          <xsl:text>&gt;</xsl:text>
+        </summary>
 
-      <xsl:text>&lt;</xsl:text>
-      <span class="start-tag"><xsl:value-of select="name(.)"/></span>
-      <xsl:apply-templates select="@*"/>
-      <xsl:text>&gt;</xsl:text>
+        <div class="expandable-children"><xsl:apply-templates/></div>
 
-      <div class="expander-content"><xsl:apply-templates/></div>
-
-      <xsl:text>&lt;/</xsl:text>
-      <span class="end-tag"><xsl:value-of select="name(.)"/></span>
-      <xsl:text>&gt;</xsl:text>
+      </details>
+      <span class="expandable-closing">
+        <xsl:text>&lt;/</xsl:text>
+        <span class="end-tag"><xsl:value-of select="name(.)"/></span>
+        <xsl:text>&gt;</xsl:text>
+      </span>
     </div>
   </xsl:template>
 
@@ -92,15 +98,15 @@
   </xsl:template>
 
   <xsl:template match="processing-instruction()[string-length(.) &gt; 50]">
-    <div class="expander-open">
-      <xsl:call-template name="expander"/>
-
-      <span class="pi">
-        <xsl:text> &lt;?</xsl:text>
-        <xsl:value-of select="name(.)"/>
-      </span>
-      <div class="expander-content pi"><xsl:value-of select="."/></div>
-      <span class="pi">
+    <div class="pi">
+      <details open="" class="expandable-body">
+        <summary class="expandable-opening">
+          <xsl:text>&lt;?</xsl:text>
+          <xsl:value-of select="name(.)"/>
+        </summary>
+        <div class="expandable-children"><xsl:value-of select="."/></div>
+      </details>
+      <span class="expandable-closing">
         <xsl:text>?&gt;</xsl:text>
       </span>
     </div>
@@ -115,23 +121,19 @@
   </xsl:template>
 
   <xsl:template match="comment()[string-length(.) &gt; 50]">
-    <div class="expander-open">
-      <xsl:call-template name="expander"/>
-
-      <span class="comment">
-        <xsl:text>&lt;!--</xsl:text>
-      </span>
-      <div class="expander-content comment">
-        <xsl:value-of select="."/>
-      </div>
-      <span class="comment">
+    <div class="comment">
+      <details open="" class="expandable-body">
+        <summary class="expandable-opening">
+          <xsl:text>&lt;!--</xsl:text>
+        </summary>
+        <div class="expandable-children">
+          <xsl:value-of select="."/>
+        </div>
+      </details>
+      <span class="expandable-closing">
         <xsl:text>--&gt;</xsl:text>
-      </span> 
+      </span>
     </div>
   </xsl:template>
-  
-  <xsl:template name="expander">
-    <div class="expander">&#x2212;</div>
-  </xsl:template>
 
 </xsl:stylesheet>

From 630a574ba42058c3a41bc90dfbbac9e03db09a2b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Mon, 12 Mar 2018 07:12:13 -0400
Subject: [PATCH 10/50] servo: Merge #20274 - style: Make the generated
 bindings really be formatted (from emilio:moz-src); r=xidorn

TOOLTOOL_DIR isn't passed down to the rust scripts it seems, per:

  https://treeherder.mozilla.org/#/jobs?repo=try&revision=46854db239166ab3a43d36c7a954debb56968eab

Source-Repo: https://github.com/servo/servo
Source-Revision: cdaa36df2d3113c44ed30a01d8e839ed23251d92

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 14597fa7341df9a16ab6a3fdc17a5ecd00ca6e6a
---
 servo/components/style/build_gecko.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/servo/components/style/build_gecko.rs b/servo/components/style/build_gecko.rs
index bf6ded11c341..eeb15c8e718a 100644
--- a/servo/components/style/build_gecko.rs
+++ b/servo/components/style/build_gecko.rs
@@ -207,7 +207,7 @@ mod bindings {
             let mut builder = Builder::default()
                 .rust_target(RustTarget::Stable_1_0);
             let rustfmt_path = env::var_os("MOZ_AUTOMATION").and_then(|_| {
-                env::var_os("TOOLTOOL_DIR")
+                env::var_os("TOOLTOOL_DIR").or_else(|| env::var_os("MOZ_SRC"))
             }).map(PathBuf::from);
 
             builder = match rustfmt_path {

From 4a083dee603daf5edbf6f5fbbe264a89b7be54ee Mon Sep 17 00:00:00 2001
From: Cosmin Sabou <csabou@mozilla.com>
Date: Mon, 12 Mar 2018 14:51:37 +0200
Subject: [PATCH 11/50] Backed out 3 changesets (bug 1223726) for mochitest
 devtools failures on
 devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js

Backed out changeset 1a09e6c3c0a3 (bug 1223726)
Backed out changeset 41da2897f549 (bug 1223726)
Backed out changeset fa0a1e88a238 (bug 1223726)
---
 .../test/browser_net_har_copy_all_as_har.js   | 63 +++++++------------
 .../netmonitor/test/browser_net_truncate.js   |  4 +-
 devtools/client/preferences/devtools.js       |  3 -
 ...owser_styleeditor_fetch-from-netmonitor.js |  4 --
 .../webconsole/webconsole-connection-proxy.js |  8 +--
 devtools/shared/webconsole/network-monitor.js | 19 +++---
 modules/libpref/init/all.js                   |  6 --
 7 files changed, 33 insertions(+), 74 deletions(-)

diff --git a/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js b/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js
index 8a3621b1d3aa..80b2f97b34f1 100644
--- a/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js
+++ b/devtools/client/netmonitor/src/har/test/browser_net_har_copy_all_as_har.js
@@ -10,12 +10,30 @@ add_task(async function () {
   // Disable tcp fast open, because it is setting a response header indicator
   // (bug 1352274). TCP Fast Open is not present on all platforms therefore the
   // number of response headers will vary depending on the platform.
-  await pushPref("network.tcp.tcp_fastopen_enable", false);
+  Services.prefs.setBoolPref("network.tcp.tcp_fastopen_enable", false);
   let { tab, monitor } = await initNetMonitor(SIMPLE_URL);
 
-  info("Starting test...");
+  info("Starting test... ");
 
-  let har = await reloadAndCopyAllAsHar(tab, monitor);
+  let { connector, store, windowRequire } = monitor.panelWin;
+  let Actions = windowRequire("devtools/client/netmonitor/src/actions/index");
+  let RequestListContextMenu = windowRequire(
+    "devtools/client/netmonitor/src/widgets/RequestListContextMenu");
+  let { getSortedRequests } = windowRequire(
+    "devtools/client/netmonitor/src/selectors/index");
+
+  store.dispatch(Actions.batchEnable(false));
+
+  let wait = waitForNetworkEvents(monitor, 1);
+  tab.linkedBrowser.reload();
+  await wait;
+
+  let contextMenu = new RequestListContextMenu({ connector });
+
+  await contextMenu.copyAllAsHar(getSortedRequests(store.getState()));
+
+  let jsonString = SpecialPowers.getClipboardData("text/unicode");
+  let har = JSON.parse(jsonString);
 
   // Check out HAR log
   isnot(har.log, null, "The HAR log must exist");
@@ -42,44 +60,5 @@ add_task(async function () {
     "Check response body");
   isnot(entry.timings, undefined, "Check timings");
 
-  // Test response body limit (non zero).
-  await pushPref("devtools.netmonitor.responseBodyLimit", 10);
-  har = await reloadAndCopyAllAsHar(tab, monitor);
-  entry = har.log.entries[0];
-  is(entry.response.content.text.length, 10, // eslint-disable-line
-    "Response body must be truncated");
-
-  // Test response body limit (zero).
-  await pushPref("devtools.netmonitor.responseBodyLimit", 0);
-  har = await reloadAndCopyAllAsHar(tab, monitor);
-  entry = har.log.entries[0];
-  is(entry.response.content.text.length, 465, // eslint-disable-line
-    "Response body must not be truncated");
-
   return teardown(monitor);
 });
-
-/**
- * Reload the page and copy all as HAR.
- */
-async function reloadAndCopyAllAsHar(tab, monitor) {
-  let { connector, store, windowRequire } = monitor.panelWin;
-  let Actions = windowRequire("devtools/client/netmonitor/src/actions/index");
-  let RequestListContextMenu = windowRequire(
-    "devtools/client/netmonitor/src/widgets/RequestListContextMenu");
-  let { getSortedRequests } = windowRequire(
-    "devtools/client/netmonitor/src/selectors/index");
-
-  store.dispatch(Actions.batchEnable(false));
-
-  let wait = waitForNetworkEvents(monitor, 1);
-  tab.linkedBrowser.reload();
-  await wait;
-
-  let contextMenu = new RequestListContextMenu({ connector });
-
-  await contextMenu.copyAllAsHar(getSortedRequests(store.getState()));
-
-  let jsonString = SpecialPowers.getClipboardData("text/unicode");
-  return JSON.parse(jsonString);
-}
diff --git a/devtools/client/netmonitor/test/browser_net_truncate.js b/devtools/client/netmonitor/test/browser_net_truncate.js
index 83245b27d219..34cca60a69fa 100644
--- a/devtools/client/netmonitor/test/browser_net_truncate.js
+++ b/devtools/client/netmonitor/test/browser_net_truncate.js
@@ -8,8 +8,8 @@
  */
 
 add_task(async function () {
-  let limit = Services.prefs.getIntPref("devtools.netmonitor.responseBodyLimit");
-  let URL = EXAMPLE_URL + "sjs_truncate-test-server.sjs?limit=" + limit;
+  let { RESPONSE_BODY_LIMIT } = require("devtools/shared/webconsole/network-monitor");
+  let URL = EXAMPLE_URL + "sjs_truncate-test-server.sjs?limit=" + RESPONSE_BODY_LIMIT;
   let { monitor, tab } = await initNetMonitor(URL);
 
   info("Starting test... ");
diff --git a/devtools/client/preferences/devtools.js b/devtools/client/preferences/devtools.js
index d74aa32f33cc..fa800694e2cb 100644
--- a/devtools/client/preferences/devtools.js
+++ b/devtools/client/preferences/devtools.js
@@ -165,9 +165,6 @@ pref("devtools.netmonitor.visibleColumns",
   "[\"status\",\"method\",\"file\",\"domain\",\"cause\",\"type\",\"transferred\",\"contentSize\",\"waterfall\"]"
 );
 
-// Save request/response bodies yes/no.
-pref("devtools.netmonitor.saveRequestAndResponseBodies", true);
-
 // The default Network monitor HAR export setting
 pref("devtools.netmonitor.har.defaultLogDir", "");
 pref("devtools.netmonitor.har.defaultFileName", "Archive %date");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js b/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
index 7a643e65a0c0..0689e68a45ea 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
@@ -34,10 +34,6 @@ add_task(function* () {
   yield ui.selectStyleSheet(ui.editors[1].styleSheet);
   yield ui.editors[1].getSourceEditor();
 
-  // Wait till there is 5 requests in Netmonitor store.
-  // (i.e. the Styleeditor panel performed one request).
-  yield waitUntil(() => getSortedRequests(store.getState()).length == 5);
-
   info("Checking Netmonitor contents.");
   let shortRequests = [];
   let longRequests = [];
diff --git a/devtools/client/webconsole/webconsole-connection-proxy.js b/devtools/client/webconsole/webconsole-connection-proxy.js
index f69cf66c64f8..cec613095d5f 100644
--- a/devtools/client/webconsole/webconsole-connection-proxy.js
+++ b/devtools/client/webconsole/webconsole-connection-proxy.js
@@ -208,15 +208,9 @@ WebConsoleConnectionProxy.prototype = {
     this.webConsoleClient = webConsoleClient;
     this._hasNativeConsoleAPI = response.nativeConsoleAPI;
 
-    let saveBodies = Services.prefs.getBoolPref(
-      "devtools.netmonitor.saveRequestAndResponseBodies");
-
     // There is no way to view response bodies from the Browser Console, so do
     // not waste the memory.
-    if (this.webConsoleFrame.isBrowserConsole) {
-      saveBodies = false;
-    }
-
+    let saveBodies = !this.webConsoleFrame.isBrowserConsole;
     this.webConsoleFrame.setSaveRequestAndResponseBodies(saveBodies);
 
     this.webConsoleClient.on("networkEvent", this._onNetworkEvent);
diff --git a/devtools/shared/webconsole/network-monitor.js b/devtools/shared/webconsole/network-monitor.js
index 2efc5f9354d4..125ea34b3431 100644
--- a/devtools/shared/webconsole/network-monitor.js
+++ b/devtools/shared/webconsole/network-monitor.js
@@ -35,6 +35,11 @@ const HTTP_FOUND = 302;
 const HTTP_SEE_OTHER = 303;
 const HTTP_TEMPORARY_REDIRECT = 307;
 
+// The maximum number of bytes a NetworkResponseListener can hold: 1 MB
+const RESPONSE_BODY_LIMIT = 1048576;
+// Exported for testing.
+exports.RESPONSE_BODY_LIMIT = RESPONSE_BODY_LIMIT;
+
 /**
  * Check if a given network request should be logged by a network monitor
  * based on the specified filters.
@@ -274,16 +279,13 @@ function NetworkResponseListener(owner, httpActivity) {
   this.receivedData = "";
   this.httpActivity = httpActivity;
   this.bodySize = 0;
-  // Indicates if the response had a size greater than response body limit.
+  // Indicates if the response had a size greater than RESPONSE_BODY_LIMIT.
   this.truncated = false;
   // Note that this is really only needed for the non-e10s case.
   // See bug 1309523.
   let channel = this.httpActivity.channel;
   this._wrappedNotificationCallbacks = channel.notificationCallbacks;
   channel.notificationCallbacks = this;
-
-  this.responseBodyLimit = Services.prefs.getIntPref(
-    "devtools.netmonitor.responseBodyLimit");
 }
 
 NetworkResponseListener.prototype = {
@@ -395,7 +397,7 @@ NetworkResponseListener.prototype = {
   /**
    * Stores the received data, if request/response body logging is enabled. It
    * also does limit the number of stored bytes, based on the
-   * `devtools.netmonitor.responseBodyLimit` pref.
+   * RESPONSE_BODY_LIMIT constant.
    *
    * Learn more about nsIStreamListener at:
    * https://developer.mozilla.org/en/XPCOM_Interface_Reference/nsIStreamListener
@@ -413,13 +415,10 @@ NetworkResponseListener.prototype = {
     this.bodySize += count;
 
     if (!this.httpActivity.discardResponseBody) {
-      let limit = Services.prefs.getIntPref("devtools.netmonitor.responseBodyLimit");
-      if (this.receivedData.length < limit || limit == 0) {
+      if (this.receivedData.length < RESPONSE_BODY_LIMIT) {
         this.receivedData +=
           NetworkHelper.convertToUnicode(data, request.contentCharset);
-      }
-      if (this.receivedData.length > limit && limit > 0) {
-        this.receivedData = this.receivedData.substr(0, limit);
+      } else {
         this.truncated = true;
       }
     }
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index c2171e2c53c2..b4be2188f459 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1113,12 +1113,6 @@ pref("devtools.debugger.force-local", true);
 // Block tools from seeing / interacting with certified apps
 pref("devtools.debugger.forbid-certified-apps", true);
 
-// Limit for intercepted response bodies (1 MB)
-// Possible values:
-// 0 => the response body has no limit
-// n => represents max number of bytes stored
-pref("devtools.netmonitor.responseBodyLimit", 1048576);
-
 // DevTools default color unit
 pref("devtools.defaultColorUnit", "authored");
 

From 1bb1ecf431193f9698e0ee090483c2ddca1535fc Mon Sep 17 00:00:00 2001
From: Amy Chan <amy_yyc@yahoo.com>
Date: Mon, 12 Mar 2018 03:31:48 -0700
Subject: [PATCH 12/50] Bug 1444325 Replaced promiseTopicObserved with
 TestUtils.topicObserved: r=johannh

MozReview-Commit-ID: EwDv7OQRGzT

--HG--
extra : rebase_source : 79623e3f256fe157307170221469b4ba9123842b
---
 .../test/popupNotifications/browser_popupNotification.js      | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/browser/base/content/test/popupNotifications/browser_popupNotification.js b/browser/base/content/test/popupNotifications/browser_popupNotification.js
index 813010978658..824c048a6a96 100644
--- a/browser/base/content/test/popupNotifications/browser_popupNotification.js
+++ b/browser/base/content/test/popupNotifications/browser_popupNotification.js
@@ -113,7 +113,7 @@ var tests = [
       await BrowserTestUtils.browserLoaded(tab.linkedBrowser);
       isnot(gBrowser.selectedTab, tab, "new tab isn't selected");
       wrongBrowserNotificationObject.browser = gBrowser.getBrowserForTab(tab);
-      let promiseTopic = promiseTopicObserved("PopupNotifications-backgroundShow");
+      let promiseTopic = TestUtils.topicObserved("PopupNotifications-backgroundShow");
       wrongBrowserNotification = showNotification(wrongBrowserNotificationObject);
       await promiseTopic;
       is(PopupNotifications.isPanelOpen, false, "panel isn't open");
@@ -147,7 +147,7 @@ var tests = [
   // test that the removed notification isn't shown on browser re-select
   { id: "Test#6",
     async run() {
-      let promiseTopic = promiseTopicObserved("PopupNotifications-updateNotShowing");
+      let promiseTopic = TestUtils.topicObserved("PopupNotifications-updateNotShowing");
       gBrowser.selectedTab = gBrowser.tabs[gBrowser.tabs.length - 1];
       await promiseTopic;
       is(PopupNotifications.isPanelOpen, false, "panel isn't open");

From e4b9aee52918cf2517bb220419dfb05926571669 Mon Sep 17 00:00:00 2001
From: Mike Ratcliffe <mratcliffe@mozilla.com>
Date: Fri, 9 Mar 2018 13:51:37 +0000
Subject: [PATCH 13/50] Bug 1444357 - Fix race conditions caused by duplicate
 store-objects-updated events r=ochameau

This is in preparation for adding the rapid add/remove test from bug 1295761.

Changes:
- Added `tree.exists(item)` to fix an issue where `selectTreeItem()` was caled for an item that did not exist and then waited for an `store-objects-updated` event. It only ever received this event due to errors when writing tests.
- Renamed `StorageUI.onUpdate()` to `StorageUI.onEdit()` and changed it's event name to `store-objects-edit`.
- Changed tests to use `store-objects-edit` where appropriate.

MozReview-Commit-ID: IAem8Penrf9

--HG--
extra : rebase_source : b818f8647958ad0688954fe5028f8d57aa119c33
---
 devtools/client/shared/widgets/TreeWidget.js  | 19 ++++++++++++++++
 .../browser_storage_cookies_delete_all.js     |  2 +-
 .../storage/test/browser_storage_delete.js    |  2 +-
 .../test/browser_storage_delete_tree.js       |  2 +-
 .../browser_storage_delete_usercontextid.js   |  2 +-
 ...browser_storage_dynamic_updates_cookies.js | 19 ++++++----------
 ...er_storage_dynamic_updates_localStorage.js |  8 +++----
 ..._storage_dynamic_updates_sessionStorage.js |  7 +++---
 .../test/browser_storage_indexeddb_delete.js  |  3 +--
 ...rowser_storage_indexeddb_delete_blocked.js |  4 ++--
 devtools/client/storage/test/head.js          | 10 +++++++--
 devtools/client/storage/ui.js                 | 22 +++++++++----------
 12 files changed, 58 insertions(+), 42 deletions(-)

diff --git a/devtools/client/shared/widgets/TreeWidget.js b/devtools/client/shared/widgets/TreeWidget.js
index cc927b9c2c20..8678f6176989 100644
--- a/devtools/client/shared/widgets/TreeWidget.js
+++ b/devtools/client/shared/widgets/TreeWidget.js
@@ -272,6 +272,25 @@ TreeWidget.prototype = {
     this.setPlaceholderText("");
   },
 
+  /**
+   * Check if an item exists.
+   *
+   * @param {array} item
+   *        The array of ids leading up to the item.
+   */
+  exists: function (item) {
+    let bookmark = this.root;
+
+    for (let id of item) {
+      if (bookmark.items.has(id)) {
+        bookmark = bookmark.items.get(id);
+      } else {
+        return false;
+      }
+    }
+    return true;
+  },
+
   /**
    * Removes the specified item and all of its child items from the tree.
    *
diff --git a/devtools/client/storage/test/browser_storage_cookies_delete_all.js b/devtools/client/storage/test/browser_storage_cookies_delete_all.js
index b8c0418f895d..6fc8bc2a9b2a 100644
--- a/devtools/client/storage/test/browser_storage_cookies_delete_all.js
+++ b/devtools/client/storage/test/browser_storage_cookies_delete_all.js
@@ -22,7 +22,7 @@ function* performDelete(store, rowName, action) {
 
   yield selectTreeItem(store);
 
-  let eventWait = gUI.once("store-objects-updated");
+  let eventWait = gUI.once("store-objects-edit");
   let cells = getRowCells(rowName, true);
 
   yield waitForContextMenu(contextMenu, cells.name, () => {
diff --git a/devtools/client/storage/test/browser_storage_delete.js b/devtools/client/storage/test/browser_storage_delete.js
index f154c6a6827c..4d02d8ac0d66 100644
--- a/devtools/client/storage/test/browser_storage_delete.js
+++ b/devtools/client/storage/test/browser_storage_delete.js
@@ -38,7 +38,7 @@ add_task(function* () {
     let row = getRowCells(rowName);
     ok(gUI.table.items.has(rowName), `There is a row '${rowName}' in ${treeItemName}`);
 
-    let eventWait = gUI.once("store-objects-updated");
+    let eventWait = gUI.once("store-objects-edit");
 
     yield waitForContextMenu(contextMenu, row[cellToClick], () => {
       info(`Opened context menu in ${treeItemName}, row '${rowName}'`);
diff --git a/devtools/client/storage/test/browser_storage_delete_tree.js b/devtools/client/storage/test/browser_storage_delete_tree.js
index 32fd410a0d84..fbd56166c2b5 100644
--- a/devtools/client/storage/test/browser_storage_delete_tree.js
+++ b/devtools/client/storage/test/browser_storage_delete_tree.js
@@ -50,7 +50,7 @@ add_task(function* () {
     yield selectTreeItem(store);
 
     let eventName = "store-objects-" +
-      (store[0] == "cookies" ? "updated" : "cleared");
+      (store[0] == "cookies" ? "edit" : "cleared");
     let eventWait = gUI.once(eventName);
 
     let selector = `[data-id='${JSON.stringify(store)}'] > .tree-widget-item`;
diff --git a/devtools/client/storage/test/browser_storage_delete_usercontextid.js b/devtools/client/storage/test/browser_storage_delete_usercontextid.js
index c9b84771b51d..f690bbee6b43 100644
--- a/devtools/client/storage/test/browser_storage_delete_usercontextid.js
+++ b/devtools/client/storage/test/browser_storage_delete_usercontextid.js
@@ -154,7 +154,7 @@ add_task(function* () {
     let row = getRowCells(rowName);
     ok(gUI.table.items.has(rowName), `There is a row '${rowName}' in ${treeItemName}`);
 
-    let eventWait = gUI.once("store-objects-updated");
+    let eventWait = gUI.once("store-objects-edit");
 
     yield waitForContextMenu(contextMenu, row[cellToClick], () => {
       info(`Opened context menu in ${treeItemName}, row '${rowName}'`);
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
index b4ab388e8820..124f7f0f1284 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
@@ -53,8 +53,7 @@ add_task(function* () {
   checkCell(c1id, "value", "1.2.3.4.5.6.7");
 
   gWindow.addCookie("c1", '{"foo": 4,"bar":6}', "/browser");
-  yield gUI.once("sidebar-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield findVariableViewProperties(finalValue[0], false);
   yield findVariableViewProperties(finalValue[1], true);
@@ -73,7 +72,7 @@ add_task(function* () {
   // Add a new entry
   gWindow.addCookie("c3", "booyeah");
 
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -93,9 +92,7 @@ add_task(function* () {
   // Add another
   gWindow.addCookie("c4", "booyeah");
 
-  // Wait once for update and another time for value fetching
-  yield gUI.once("store-objects-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -117,8 +114,7 @@ add_task(function* () {
   // Removing cookies
   gWindow.removeCookie("c1", "/browser");
 
-  yield gUI.once("sidebar-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -141,7 +137,7 @@ add_task(function* () {
   // Keep deleting till no rows
   gWindow.removeCookie("c3");
 
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -159,8 +155,7 @@ add_task(function* () {
 
   gWindow.removeCookie("c2", "/browser");
 
-  yield gUI.once("sidebar-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -177,7 +172,7 @@ add_task(function* () {
 
   gWindow.removeCookie("c4");
 
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [["cookies", "http://test1.example.org"], [ ]],
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
index 6980e3e55444..576aadf56134 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
@@ -22,7 +22,7 @@ add_task(function* () {
 
   gWindow.localStorage.removeItem("ls4");
 
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -33,8 +33,7 @@ add_task(function* () {
 
   gWindow.localStorage.setItem("ls4", "again");
 
-  yield gUI.once("store-objects-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -45,8 +44,7 @@ add_task(function* () {
   // Updating a row
   gWindow.localStorage.setItem("ls2", "ls2-changed");
 
-  yield gUI.once("store-objects-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   checkCell("ls2", "value", "ls2-changed");
 
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
index bc2a2204cef9..4c07a2dd1e8d 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
@@ -22,8 +22,7 @@ add_task(function* () {
 
   gWindow.sessionStorage.setItem("ss4", "new-item");
 
-  yield gUI.once("store-objects-updated");
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
@@ -36,11 +35,11 @@ add_task(function* () {
 
   gWindow.sessionStorage.removeItem("ss3");
 
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   gWindow.sessionStorage.removeItem("ss1");
 
-  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-edit");
 
   yield checkState([
     [
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_delete.js b/devtools/client/storage/test/browser_storage_indexeddb_delete.js
index b4f5db7ed63e..16757a474c21 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_delete.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_delete.js
@@ -25,8 +25,7 @@ add_task(function* () {
   yield selectTreeItem(deletedDb);
 
   // Wait once for update and another time for value fetching
-  let eventWait = gUI.once("store-objects-updated").then(
-    () => gUI.once("store-objects-updated"));
+  let eventWait = gUI.once("store-objects-updated");
 
   let selector = `[data-id='${JSON.stringify(deletedDb)}'] > .tree-widget-item`;
   let target = gPanelWindow.document.querySelector(selector);
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js b/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
index b4c42bf288d0..9136bc44aa6a 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
@@ -28,7 +28,7 @@ add_task(function* () {
     [["indexedDB", "http://test1.example.org"], ["idb (default)"]]
   ]);
 
-  let eventWait = gUI.once("store-objects-updated");
+  let eventWait = gUI.once("store-objects-edit");
 
   info("telling content to close the db");
   yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
@@ -36,7 +36,7 @@ add_task(function* () {
     yield win.closeDb();
   });
 
-  info("waiting for store update events");
+  info("waiting for store edit events");
   yield eventWait;
 
   info("test state after real delete");
diff --git a/devtools/client/storage/test/head.js b/devtools/client/storage/test/head.js
index 5d51c855c09b..57c2c6934a55 100644
--- a/devtools/client/storage/test/head.js
+++ b/devtools/client/storage/test/head.js
@@ -512,11 +512,17 @@ function matchVariablesViewProperty(prop, rule) {
  *        The array id of the item in the tree
  */
 function* selectTreeItem(ids) {
-  /* If this item is already selected, return */
   if (gUI.tree.isSelected(ids)) {
+    info(`"${ids}" is already selected, returning.`);
+    return;
+  }
+  if (!gUI.tree.exists(ids)) {
+    info(`"${ids}" does not exist, returning.`);
     return;
   }
 
+  // The item exists but is not selected... select it.
+  info(`Selecting "${ids}".`);
   let updated = gUI.once("store-objects-updated");
   gUI.tree.selectedItem = ids;
   yield updated;
@@ -979,7 +985,7 @@ function* performAdd(store) {
   }
 
   let eventEdit = gUI.table.once("row-edit");
-  let eventWait = gUI.once("store-objects-updated");
+  let eventWait = gUI.once("store-objects-edit");
 
   menuAdd.click();
 
diff --git a/devtools/client/storage/ui.js b/devtools/client/storage/ui.js
index 51911630948e..109a14e17b47 100644
--- a/devtools/client/storage/ui.js
+++ b/devtools/client/storage/ui.js
@@ -141,8 +141,8 @@ class StorageUI {
       console.error(e);
     });
 
-    this.onUpdate = this.onUpdate.bind(this);
-    this.front.on("stores-update", this.onUpdate);
+    this.onEdit = this.onEdit.bind(this);
+    this.front.on("stores-update", this.onEdit);
     this.onCleared = this.onCleared.bind(this);
     this.front.on("stores-cleared", this.onCleared);
 
@@ -216,7 +216,7 @@ class StorageUI {
     this.table.off(TableWidget.EVENTS.CELL_EDIT, this.editItem);
     this.table.destroy();
 
-    this.front.off("stores-update", this.onUpdate);
+    this.front.off("stores-update", this.onEdit);
     this.front.off("stores-cleared", this.onCleared);
     this._panelDoc.removeEventListener("keypress", this.handleKeypress);
     this.searchBox.removeEventListener("input", this.filterItems);
@@ -401,7 +401,7 @@ class StorageUI {
    *        of the changed store objects. This array is empty for deleted object
    *        if the host was completely removed.
    */
-  async onUpdate({ changed, added, deleted }) {
+  async onEdit({ changed, added, deleted }) {
     if (added) {
       await this.handleAddedItems(added);
     }
@@ -421,14 +421,14 @@ class StorageUI {
     }
 
     if (added || deleted || changed) {
-      this.emit("store-objects-updated");
+      this.emit("store-objects-edit");
     }
   }
 
   /**
-   * Handle added items received by onUpdate
+   * Handle added items received by onEdit
    *
-   * @param {object} See onUpdate docs
+   * @param {object} See onEdit docs
    */
   async handleAddedItems(added) {
     for (let type in added) {
@@ -460,9 +460,9 @@ class StorageUI {
   }
 
   /**
-   * Handle deleted items received by onUpdate
+   * Handle deleted items received by onEdit
    *
-   * @param {object} See onUpdate docs
+   * @param {object} See onEdit docs
    */
   async handleDeletedItems(deleted) {
     for (let type in deleted) {
@@ -512,9 +512,9 @@ class StorageUI {
   }
 
   /**
-   * Handle changed items received by onUpdate
+   * Handle changed items received by onEdit
    *
-   * @param {object} See onUpdate docs
+   * @param {object} See onEdit docs
    */
   async handleChangedItems(changed) {
     let [type, host, db, objectStore] = this.tree.selectedItem;

From 28f08cc0dca853edae46358ccd52589aeac67cc6 Mon Sep 17 00:00:00 2001
From: Mark Banner <standard8@mozilla.com>
Date: Wed, 7 Mar 2018 17:24:01 +0000
Subject: [PATCH 14/50] Bug 1443835 - Prevent modifications to the root folder
 via PlacesUtils.bookmarks.insert and PlacesUtils.bookmarks.update. r=mak

MozReview-Commit-ID: KQjxc3PA2SY

--HG--
extra : rebase_source : 1a6063f424271ac3bfdae23af25a4e8abdd71ac9
---
 .../places/tests/browser/browser.ini          |   1 -
 .../browser_0_library_left_pane_migration.js  |  87 ----------
 .../components/places/tests/chrome/chrome.ini |   1 -
 .../chrome/test_0_multiple_left_pane.xul      |  78 ---------
 .../sync/tests/unit/test_bookmark_tracker.js  | 125 --------------
 .../components/places/BookmarkJSONUtils.jsm   |   8 +-
 toolkit/components/places/Bookmarks.jsm       |   5 +-
 .../test_417228-exclude-from-backup.js        | 142 ----------------
 .../bookmarks/test_417228-other-roots.js      | 152 ------------------
 .../tests/bookmarks/test_bookmarks_insert.js  |  19 +++
 .../tests/bookmarks/test_bookmarks_remove.js  |   8 -
 .../tests/bookmarks/test_bookmarks_update.js  |  32 +++-
 .../places/tests/bookmarks/xpcshell.ini       |   2 -
 .../places/tests/queries/head_queries.js      |   2 +-
 .../places/tests/sync/test_sync_utils.js      |  79 ---------
 .../tests/unit/test_async_transactions.js     |  46 +++---
 16 files changed, 83 insertions(+), 704 deletions(-)
 delete mode 100644 browser/components/places/tests/browser/browser_0_library_left_pane_migration.js
 delete mode 100644 browser/components/places/tests/chrome/test_0_multiple_left_pane.xul
 delete mode 100644 toolkit/components/places/tests/bookmarks/test_417228-exclude-from-backup.js
 delete mode 100644 toolkit/components/places/tests/bookmarks/test_417228-other-roots.js

diff --git a/browser/components/places/tests/browser/browser.ini b/browser/components/places/tests/browser/browser.ini
index 03fa30232f80..85e4c2c0badd 100644
--- a/browser/components/places/tests/browser/browser.ini
+++ b/browser/components/places/tests/browser/browser.ini
@@ -11,7 +11,6 @@ support-files =
   sidebarpanels_click_test_page.html
   keyword_form.html
 
-[browser_0_library_left_pane_migration.js]
 [browser_addBookmarkForFrame.js]
 [browser_bookmark_add_tags.js]
 skip-if = (os == 'win' && ccov) # Bug 1423667
diff --git a/browser/components/places/tests/browser/browser_0_library_left_pane_migration.js b/browser/components/places/tests/browser/browser_0_library_left_pane_migration.js
deleted file mode 100644
index 62909d8f7e5e..000000000000
--- a/browser/components/places/tests/browser/browser_0_library_left_pane_migration.js
+++ /dev/null
@@ -1,87 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* vim:set ts=2 sw=2 sts=2 et: */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-"use strict";
-
-/**
- *  Test we correctly migrate Library left pane to the latest version.
- *  Note: this test MUST be the first between browser chrome tests, or results
- *        of next tests could be unexpected due to PlacesUIUtils getters.
- */
-
-const TEST_URI = "http://www.mozilla.org/";
-
-add_task(async function() {
-  ok(PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION > 0,
-     "Left pane version in chrome context, current version is: " + PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION );
-
-  // Check if we have any left pane folder already set, remove it eventually.
-  let leftPaneItems = PlacesUtils.annotations
-                                 .getItemsWithAnnotation(PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-  if (leftPaneItems.length > 0) {
-    // The left pane has already been created, touching it now would cause
-    // next tests to rely on wrong values (and possibly crash)
-    is(leftPaneItems.length, 1, "We correctly have only 1 left pane folder");
-    // Check version.
-    let version = PlacesUtils.annotations.getItemAnnotation(leftPaneItems[0],
-                                                            PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-    is(version, PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION, "Left pane version is actual");
-    ok(true, "left pane has already been created, skipping test");
-    return;
-  }
-
-  // Create a fake left pane folder with an old version (current version - 1).
-  let folder = await PlacesUtils.bookmarks.insert({
-    parentGuid: PlacesUtils.bookmarks.rootGuid,
-    index: PlacesUtils.bookmarks.DEFAULT_INDEX,
-    type: PlacesUtils.bookmarks.TYPE_FOLDER,
-    title: ""
-  });
-
-  let folderId = await PlacesUtils.promiseItemId(folder.guid);
-  PlacesUtils.annotations.setItemAnnotation(folderId,
-                                            PlacesUIUtils.ORGANIZER_FOLDER_ANNO,
-                                            PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION - 1,
-                                            0,
-                                            PlacesUtils.annotations.EXPIRE_NEVER);
-
-  // Check fake left pane root has been correctly created.
-  leftPaneItems =
-    PlacesUtils.annotations.getItemsWithAnnotation(PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-  is(leftPaneItems.length, 1, "We correctly have only 1 left pane folder");
-  is(leftPaneItems[0], folderId, "left pane root itemId is correct");
-
-  // Check version.
-  let version = PlacesUtils.annotations.getItemAnnotation(folderId,
-                                                          PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-  is(version, PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION - 1, "Left pane version correctly set");
-
-  // Open Library, this will upgrade our left pane version.
-  let organizer = await promiseLibrary();
-
-  // Check left pane.
-  ok(PlacesUIUtils.leftPaneFolderId > 0, "Left pane folder correctly created");
-  leftPaneItems =
-    PlacesUtils.annotations.getItemsWithAnnotation(PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-  is(leftPaneItems.length, 1, "We correctly have only 1 left pane folder");
-  let leftPaneRoot = leftPaneItems[0];
-  is(leftPaneRoot, PlacesUIUtils.leftPaneFolderId,
-     "leftPaneFolderId getter has correct value");
-
-  // Check version has been upgraded.
-  version = PlacesUtils.annotations.getItemAnnotation(leftPaneRoot,
-                                                      PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-  is(version, PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION,
-     "Left pane version has been correctly upgraded");
-
-  // Check left pane is populated.
-  organizer.PlacesOrganizer.selectLeftPaneBuiltIn("History");
-  is(organizer.PlacesOrganizer._places.selectedNode.itemId,
-     PlacesUIUtils.leftPaneQueries.History,
-     "Library left pane is populated and working");
-
-  await promiseLibraryClosed(organizer);
-});
diff --git a/browser/components/places/tests/chrome/chrome.ini b/browser/components/places/tests/chrome/chrome.ini
index b07430313438..74747d72d50e 100644
--- a/browser/components/places/tests/chrome/chrome.ini
+++ b/browser/components/places/tests/chrome/chrome.ini
@@ -2,7 +2,6 @@
 support-files = head.js
 
 [test_0_bug510634.xul]
-[test_0_multiple_left_pane.xul]
 [test_bug1163447_selectItems_through_shortcut.xul]
 skip-if = (os == 'win' && ccov) # Bug 1423667
 [test_bug427633_no_newfolder_if_noip.xul]
diff --git a/browser/components/places/tests/chrome/test_0_multiple_left_pane.xul b/browser/components/places/tests/chrome/test_0_multiple_left_pane.xul
deleted file mode 100644
index 9bf7c94d3478..000000000000
--- a/browser/components/places/tests/chrome/test_0_multiple_left_pane.xul
+++ /dev/null
@@ -1,78 +0,0 @@
-<?xml version="1.0"?>
-
-<!-- This Source Code Form is subject to the terms of the Mozilla Public
-   - License, v. 2.0. If a copy of the MPL was not distributed with this
-   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-
-<!-- Bug 466422:
-   - Check that we replace the left pane with a correct one if it gets corrupted
-   - and we end up having more than one. -->
-
-<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
-<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css"
-                 type="text/css"?>
-
-<?xml-stylesheet href="chrome://browser/content/places/places.css"?>
-<?xml-stylesheet href="chrome://browser/skin/places/places.css"?>
-
-<?xul-overlay href="chrome://browser/content/places/placesOverlay.xul"?>
-
-<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
-        title="Test handling of multiple left pane folders"
-        onload="runTest();">
-
-  <script type="application/javascript"
-          src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js" />
-
-  <body xmlns="http://www.w3.org/1999/xhtml">
-    <p id="display"></p>
-    <div id="content" style="display: none"></div>
-    <pre id="test"></pre>
-  </body>
-
-  <script type="application/javascript">
-  <![CDATA[
-
-    function runTest() {
-      SimpleTest.waitForExplicitFinish();
-
-      (async function() {
-        let fakeLeftPanes = [];
-        // We need 2 left pane folders to simulate a corrupt profile.
-        do {
-          let leftPaneItems = PlacesUtils.annotations.getItemsWithAnnotation(PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-
-          // Create a fake left pane folder.
-          let folder = await PlacesUtils.bookmarks.insert({
-            parentGuid: PlacesUtils.bookmarks.rootGuid,
-            index: PlacesUtils.bookmarks.DEFAULT_INDEX,
-            type: PlacesUtils.bookmarks.TYPE_FOLDER
-          });
-
-          let fakeLeftPaneRoot = await PlacesUtils.promiseItemId(folder.guid);
-          PlacesUtils.annotations.setItemAnnotation(fakeLeftPaneRoot, PlacesUIUtils.ORGANIZER_FOLDER_ANNO,
-                               PlacesUIUtils.ORGANIZER_LEFTPANE_VERSION, 0,
-                               PlacesUtils.annotations.EXPIRE_NEVER);
-          fakeLeftPanes.push(folder.guid);
-        } while (fakeLeftPanes.length < 2);
-
-        // Initialize the left pane queries.
-        PlacesUIUtils.leftPaneFolderId;
-
-        // Check left pane.
-        ok(PlacesUIUtils.leftPaneFolderId > 0,
-           "Left pane folder correctly created");
-        let leftPaneItems = PlacesUtils.annotations.getItemsWithAnnotation(PlacesUIUtils.ORGANIZER_FOLDER_ANNO);
-        is(leftPaneItems.length, 1,
-           "We correctly have only 1 left pane folder");
-
-        // Check that all old left pane items have been removed.
-        for (let guid of fakeLeftPanes) {
-          ok(!(await PlacesUtils.bookmarks.fetch({guid})), "This folder should have been removed");
-        }
-      })().then(() => SimpleTest.finish());
-    }
-  ]]>
-  </script>
-
-</window>
diff --git a/services/sync/tests/unit/test_bookmark_tracker.js b/services/sync/tests/unit/test_bookmark_tracker.js
index 2ba7f852629c..d916b1775509 100644
--- a/services/sync/tests/unit/test_bookmark_tracker.js
+++ b/services/sync/tests/unit/test_bookmark_tracker.js
@@ -200,131 +200,6 @@ function setAnnoUnchecked(itemId, name, value, type) {
   );
 }
 
-add_task(async function test_leftPaneFolder() {
-  _("Ensure we never track left pane roots");
-
-  try {
-    await startTracking();
-
-    // Creates the organizer queries as a side effect.
-    let leftPaneId = PlacesUIUtils.maybeRebuildLeftPane();
-    _(`Left pane root ID: ${leftPaneId}`);
-
-    {
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(changes, {}, "New left pane queries should not be tracked");
-      Assert.equal(tracker.score, SCORE_INCREMENT_XLARGE);
-    }
-
-    _("Reset synced bookmarks to simulate a disconnect");
-    await PlacesSyncUtils.bookmarks.reset();
-
-    {
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(Object.keys(changes).sort(), ["menu", "mobile", "toolbar", "unfiled"],
-        "Left pane queries should not be tracked after reset");
-      Assert.equal(tracker.score, SCORE_INCREMENT_XLARGE);
-      await PlacesTestUtils.markBookmarksAsSynced();
-    }
-
-    // The following tests corrupt the left pane queries in different ways.
-    // `PlacesUIUtils.maybeRebuildLeftPane` will rebuild the entire root, but
-    // none of those changes should be tracked by Sync.
-
-    _("Annotate unrelated folder as left pane root");
-    {
-      let folder = await PlacesUtils.bookmarks.insert({
-        parentGuid: PlacesUtils.bookmarks.rootGuid,
-        type: PlacesUtils.bookmarks.TYPE_FOLDER,
-        title: "Fake left pane root",
-      });
-      let folderId = await PlacesUtils.promiseItemId(folder.guid);
-      await setAnnoUnchecked(folderId, PlacesUIUtils.ORGANIZER_FOLDER_ANNO, 0,
-                             PlacesUtils.annotations.TYPE_INT32);
-
-      leftPaneId = PlacesUIUtils.maybeRebuildLeftPane();
-      _(`Left pane root ID after deleting unrelated folder: ${leftPaneId}`);
-
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(changes, {},
-        "Should not track left pane items after deleting unrelated folder");
-    }
-
-    _("Corrupt organizer left pane version");
-    {
-      await setAnnoUnchecked(leftPaneId, PlacesUIUtils.ORGANIZER_FOLDER_ANNO,
-                             -1, PlacesUtils.annotations.TYPE_INT32);
-
-      leftPaneId = PlacesUIUtils.maybeRebuildLeftPane();
-      _(`Left pane root ID after restoring version: ${leftPaneId}`);
-
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(changes, {},
-        "Should not track left pane items after restoring version");
-    }
-
-    _("Set left pane anno on nonexistent item");
-    {
-      await setAnnoUnchecked(999, PlacesUIUtils.ORGANIZER_QUERY_ANNO,
-                             "Tags", PlacesUtils.annotations.TYPE_STRING);
-
-      leftPaneId = PlacesUIUtils.maybeRebuildLeftPane();
-      _(`Left pane root ID after detecting nonexistent item: ${leftPaneId}`);
-
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(changes, {},
-        "Should not track left pane items after detecting nonexistent item");
-    }
-
-    _("Move query out of left pane root");
-    {
-      let queryId = await PlacesUIUtils.leftPaneQueries.Downloads;
-      let queryGuid = await PlacesUtils.promiseItemGuid(queryId);
-      await PlacesUtils.bookmarks.update({
-        guid: queryGuid,
-        parentGuid: PlacesUtils.bookmarks.rootGuid,
-        index: PlacesUtils.bookmarks.DEFAULT_INDEX,
-      });
-
-      leftPaneId = PlacesUIUtils.maybeRebuildLeftPane();
-      _(`Left pane root ID after restoring moved query: ${leftPaneId}`);
-
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(changes, {},
-        "Should not track left pane items after restoring moved query");
-    }
-
-    _("Add duplicate query");
-    {
-      let leftPaneGuid = await PlacesUtils.promiseItemGuid(leftPaneId);
-      let query = await PlacesUtils.bookmarks.insert({
-        parentGuid: leftPaneGuid,
-        url: `place:folder=TAGS`,
-      });
-      let queryId = await PlacesUtils.promiseItemId(query.guid);
-      await setAnnoUnchecked(queryId, PlacesUIUtils.ORGANIZER_QUERY_ANNO,
-                             "Tags", PlacesUtils.annotations.TYPE_STRING);
-
-      leftPaneId = PlacesUIUtils.maybeRebuildLeftPane();
-      _(`Left pane root ID after removing dupe query: ${leftPaneId}`);
-
-      await PlacesTestUtils.promiseAsyncUpdates();
-      let changes = await tracker.getChangedIDs();
-      deepEqual(changes, {},
-        "Should not track left pane items after removing dupe query");
-    }
-  } finally {
-    _("Clean up.");
-    await cleanup();
-  }
-});
-
 add_task(async function test_tracking() {
   _("Test starting and stopping the tracker");
 
diff --git a/toolkit/components/places/BookmarkJSONUtils.jsm b/toolkit/components/places/BookmarkJSONUtils.jsm
index 6bfa865aec41..c9b90d3a501c 100644
--- a/toolkit/components/places/BookmarkJSONUtils.jsm
+++ b/toolkit/components/places/BookmarkJSONUtils.jsm
@@ -267,12 +267,10 @@ BookmarkImporter.prototype = {
         continue;
       }
 
-      // Places is moving away from supporting user-defined folders at the top
-      // of the tree, however, until we have a migration strategy we need to
-      // ensure any non-built-in folders are created (xref bug 1310299).
+      // Drop any roots whose guid we don't recognise - we don't support anything
+      // apart from the built-in roots.
       if (!PlacesUtils.bookmarks.userContentRoots.includes(node.guid)) {
-        node.parentGuid = PlacesUtils.bookmarks.rootGuid;
-        await PlacesUtils.bookmarks.insert(node);
+        continue;
       }
 
       await PlacesUtils.bookmarks.insertTree(node, { fixupOrSkipInvalidEntries: true });
diff --git a/toolkit/components/places/Bookmarks.jsm b/toolkit/components/places/Bookmarks.jsm
index 072a87f8ea45..84668f54c5cd 100644
--- a/toolkit/components/places/Bookmarks.jsm
+++ b/toolkit/components/places/Bookmarks.jsm
@@ -241,7 +241,9 @@ var Bookmarks = Object.freeze({
         index: { defaultValue: this.DEFAULT_INDEX },
         url: { requiredIf: b => b.type == this.TYPE_BOOKMARK,
                validIf: b => b.type == this.TYPE_BOOKMARK },
-        parentGuid: { required: true },
+        parentGuid: { required: true,
+                      // Inserting into the root folder is not allowed.
+                      validIf: b => b.parentGuid != this.rootGuid },
         title: { defaultValue: "",
                  validIf: b => b.type == this.TYPE_BOOKMARK ||
                                b.type == this.TYPE_FOLDER ||
@@ -610,6 +612,7 @@ var Bookmarks = Object.freeze({
       { guid: { required: true },
         index: { requiredIf: b => b.hasOwnProperty("parentGuid"),
                  validIf: b => b.index >= 0 || b.index == this.DEFAULT_INDEX },
+        parentGuid: { validIf: b => b.parentGuid != this.rootGuid },
         source: { defaultValue: this.SOURCES.DEFAULT }
       });
 
diff --git a/toolkit/components/places/tests/bookmarks/test_417228-exclude-from-backup.js b/toolkit/components/places/tests/bookmarks/test_417228-exclude-from-backup.js
deleted file mode 100644
index 7be66c9f9d0e..000000000000
--- a/toolkit/components/places/tests/bookmarks/test_417228-exclude-from-backup.js
+++ /dev/null
@@ -1,142 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* vim:set ts=2 sw=2 sts=2 et: */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-// Menu, Toolbar, Unsorted, Tags, Mobile
-const PLACES_ROOTS_COUNT  = 5;
-
-/*
-
-Backup/restore tests example:
-
-var myTest = {
-  populate: function () { ... add bookmarks ... },
-  validate: function () { ... query for your bookmarks ... }
-}
-
-this.push(myTest);
-
-*/
-
-var test = {
-  populate: function populate() {
-    // check initial size
-    var rootNode = PlacesUtils.getFolderContents(PlacesUtils.placesRootId,
-                                                 false, false).root;
-    Assert.equal(rootNode.childCount, PLACES_ROOTS_COUNT );
-    rootNode.containerOpen = false;
-
-    var idx = PlacesUtils.bookmarks.DEFAULT_INDEX;
-
-    // create a root to be restore
-    this._restoreRootTitle = "restore root";
-    var restoreRootId = PlacesUtils.bookmarks
-                                   .createFolder(PlacesUtils.placesRootId,
-                                                 this._restoreRootTitle, idx);
-    // add a test bookmark
-    this._restoreRootURI = uri("http://restore.uri");
-    PlacesUtils.bookmarks.insertBookmark(restoreRootId, this._restoreRootURI,
-                                         idx, "restore uri");
-    // add a test bookmark to be exclude
-    this._restoreRootExcludeURI = uri("http://exclude.uri");
-    var exItemId = PlacesUtils.bookmarks
-                              .insertBookmark(restoreRootId,
-                                              this._restoreRootExcludeURI,
-                                              idx, "exclude uri");
-    // Annotate the bookmark for exclusion.
-    PlacesUtils.annotations.setItemAnnotation(exItemId,
-                                              PlacesUtils.EXCLUDE_FROM_BACKUP_ANNO, 1, 0,
-                                              PlacesUtils.annotations.EXPIRE_NEVER);
-
-    // create a root to be exclude
-    this._excludeRootTitle = "exclude root";
-    this._excludeRootId = PlacesUtils.bookmarks
-                                     .createFolder(PlacesUtils.placesRootId,
-                                                   this._excludeRootTitle, idx);
-    // Annotate the root for exclusion.
-    PlacesUtils.annotations.setItemAnnotation(this._excludeRootId,
-                                              PlacesUtils.EXCLUDE_FROM_BACKUP_ANNO, 1, 0,
-                                              PlacesUtils.annotations.EXPIRE_NEVER);
-    // add a test bookmark exclude by exclusion of its parent
-    PlacesUtils.bookmarks.insertBookmark(this._excludeRootId,
-                                         this._restoreRootExcludeURI,
-                                         idx, "exclude uri");
-  },
-
-  validate: function validate(aEmptyBookmarks) {
-    var rootNode = PlacesUtils.getFolderContents(PlacesUtils.placesRootId,
-                                                 false, false).root;
-
-    if (!aEmptyBookmarks) {
-      // since restore does not remove backup exclude items both
-      // roots should still exist.
-      Assert.equal(rootNode.childCount, PLACES_ROOTS_COUNT + 2);
-      // open exclude root and check it still contains one item
-      var restoreRootIndex = PLACES_ROOTS_COUNT;
-      var excludeRootIndex = PLACES_ROOTS_COUNT + 1;
-      var excludeRootNode = rootNode.getChild(excludeRootIndex);
-      Assert.equal(this._excludeRootTitle, excludeRootNode.title);
-      excludeRootNode.QueryInterface(Ci.nsINavHistoryQueryResultNode);
-      excludeRootNode.containerOpen = true;
-      Assert.equal(excludeRootNode.childCount, 1);
-      var excludeRootChildNode = excludeRootNode.getChild(0);
-      Assert.equal(excludeRootChildNode.uri, this._restoreRootExcludeURI.spec);
-      excludeRootNode.containerOpen = false;
-    } else {
-      // exclude root should not exist anymore
-      Assert.equal(rootNode.childCount, PLACES_ROOTS_COUNT + 1);
-      restoreRootIndex = PLACES_ROOTS_COUNT;
-    }
-
-    var restoreRootNode = rootNode.getChild(restoreRootIndex);
-    Assert.equal(this._restoreRootTitle, restoreRootNode.title);
-    restoreRootNode.QueryInterface(Ci.nsINavHistoryQueryResultNode);
-    restoreRootNode.containerOpen = true;
-    Assert.equal(restoreRootNode.childCount, 1);
-    var restoreRootChildNode = restoreRootNode.getChild(0);
-    Assert.equal(restoreRootChildNode.uri, this._restoreRootURI.spec);
-    restoreRootNode.containerOpen = false;
-
-    rootNode.containerOpen = false;
-  }
-};
-
-// make json file
-var jsonFile;
-
-add_task(async function setup() {
-  jsonFile = OS.Path.join(OS.Constants.Path.profileDir, "bookmarks.json");
-});
-
-add_task(async function test_export_import_excluded_file() {
-  // populate db
-  test.populate();
-
-  await BookmarkJSONUtils.exportToFile(jsonFile);
-
-  // restore json file
-  info("Restoring json file");
-  await BookmarkJSONUtils.importFromFile(jsonFile, true);
-
-  // validate without removing all bookmarks
-  // restore do not remove backup exclude entries
-  info("Validating...");
-  test.validate(false);
-});
-
-add_task(async function test_clearing_then_importing() {
-  // cleanup
-  await PlacesUtils.bookmarks.eraseEverything();
-  // manually remove the excluded root
-  PlacesUtils.bookmarks.removeItem(test._excludeRootId);
-  // restore json file
-  await BookmarkJSONUtils.importFromFile(jsonFile, true);
-
-  // validate after a complete bookmarks cleanup
-  test.validate(true);
-
-  // clean up
-  await OS.File.remove(jsonFile);
-});
diff --git a/toolkit/components/places/tests/bookmarks/test_417228-other-roots.js b/toolkit/components/places/tests/bookmarks/test_417228-other-roots.js
deleted file mode 100644
index 9b87144e1ad3..000000000000
--- a/toolkit/components/places/tests/bookmarks/test_417228-other-roots.js
+++ /dev/null
@@ -1,152 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* vim:set ts=2 sw=2 sts=2 et: */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-var tests = [];
-
-/*
-
-Backup/restore tests example:
-
-var myTest = {
-  populate: function () { ... add bookmarks ... },
-  validate: function () { ... query for your bookmarks ... }
-}
-
-this.push(myTest);
-
-*/
-
-tests.push({
-  // Initialise something to avoid undefined property warnings in validate.
-  _litterTitle: "",
-
-  async populate() {
-    // check initial size
-    var rootNode = PlacesUtils.getFolderContents(PlacesUtils.placesRootId,
-                                                 false, false).root;
-    Assert.equal(rootNode.childCount, 5);
-
-    // create a test root
-    this._folderTitle = "test folder";
-    this._folderId =
-      PlacesUtils.bookmarks.createFolder(PlacesUtils.placesRootId,
-                                         this._folderTitle,
-                                         PlacesUtils.bookmarks.DEFAULT_INDEX);
-    Assert.equal(rootNode.childCount, 6);
-
-    // add a tag
-    this._testURI = Services.io.newURI("http://test");
-    this._tags = ["a", "b"];
-    PlacesUtils.tagging.tagURI(this._testURI, this._tags);
-
-    // add a child to each root, including our test root
-    await PlacesUtils.bookmarks.eraseEverything();
-    this._roots = [PlacesUtils.bookmarksMenuFolderId, PlacesUtils.toolbarFolderId,
-                   PlacesUtils.unfiledBookmarksFolderId, PlacesUtils.mobileFolderId,
-                   this._folderId];
-
-    this._roots.forEach(aRootId => {
-          // add a test bookmark
-      PlacesUtils.bookmarks.insertBookmark(aRootId, this._testURI,
-                                           PlacesUtils.bookmarks.DEFAULT_INDEX, "test");
-    });
-
-    // add a folder to exclude from replacing during restore
-    // this will still be present post-restore
-    var excludedFolderId =
-      PlacesUtils.bookmarks.createFolder(PlacesUtils.placesRootId,
-                                         "excluded",
-                                         PlacesUtils.bookmarks.DEFAULT_INDEX);
-    Assert.equal(rootNode.childCount, 7);
-
-    // add a test bookmark to it
-    PlacesUtils.bookmarks.insertBookmark(excludedFolderId, this._testURI,
-                                         PlacesUtils.bookmarks.DEFAULT_INDEX, "test");
-  },
-
-  inbetween: function inbetween() {
-    // add some items that should be removed by the restore
-
-    // add a folder
-    this._litterTitle = "otter";
-    PlacesUtils.bookmarks.createFolder(PlacesUtils.placesRootId,
-                                       this._litterTitle, 0);
-
-    // add some tags
-    PlacesUtils.tagging.tagURI(this._testURI, ["c", "d"]);
-  },
-
-  validate: function validate() {
-    // validate tags restored
-    var tags = PlacesUtils.tagging.getTagsForURI(this._testURI);
-    // also validates that litter tags are gone
-    Assert.equal(this._tags.toString(), tags.toString());
-
-    var rootNode = PlacesUtils.getFolderContents(PlacesUtils.placesRootId,
-                                                 false, false).root;
-
-    // validate litter is gone
-    Assert.notEqual(rootNode.getChild(0).title, this._litterTitle);
-
-    // test root count is the same
-    Assert.equal(rootNode.childCount, 7);
-
-    var foundTestFolder = 0;
-    for (var i = 0; i < rootNode.childCount; i++) {
-      var node = rootNode.getChild(i);
-
-      info("validating " + node.title);
-      if (node.itemId != PlacesUtils.tagsFolderId) {
-        if (node.title == this._folderTitle) {
-          // check the test folder's properties
-          Assert.equal(node.type, node.RESULT_TYPE_FOLDER);
-          Assert.equal(node.title, this._folderTitle);
-          foundTestFolder++;
-        }
-
-        // test contents
-        node.QueryInterface(Ci.nsINavHistoryContainerResultNode).containerOpen = true;
-        Assert.equal(node.childCount, 1);
-        var child = node.getChild(0);
-        Assert.ok(Services.io.newURI(child.uri).equals(this._testURI));
-
-        // clean up
-        node.containerOpen = false;
-      }
-    }
-    Assert.equal(foundTestFolder, 1);
-    rootNode.containerOpen = false;
-  }
-});
-
-add_task(async function() {
-  // make json file
-  let jsonFile = OS.Path.join(OS.Constants.Path.profileDir, "bookmarks.json");
-
-  // populate db
-  for (let test of tests) {
-    await test.populate();
-    // sanity
-    test.validate();
-  }
-
-  await BookmarkJSONUtils.exportToFile(jsonFile);
-
-  tests.forEach(function(aTest) {
-    aTest.inbetween();
-  });
-
-  // restore json file
-  await BookmarkJSONUtils.importFromFile(jsonFile, true);
-
-  // validate
-  tests.forEach(function(aTest) {
-    aTest.validate();
-  });
-
-  // clean up
-  await OS.File.remove(jsonFile);
-});
diff --git a/toolkit/components/places/tests/bookmarks/test_bookmarks_insert.js b/toolkit/components/places/tests/bookmarks/test_bookmarks_insert.js
index 2497f3387a06..98004575b049 100644
--- a/toolkit/components/places/tests/bookmarks/test_bookmarks_insert.js
+++ b/toolkit/components/places/tests/bookmarks/test_bookmarks_insert.js
@@ -91,6 +91,25 @@ add_task(async function invalid_properties_for_bookmark_type() {
                 /Invalid value for property 'title'/);
 });
 
+add_task(async function test_insert_into_root_throws() {
+  Assert.throws(() =>
+    PlacesUtils.bookmarks.insert({
+      parentGuid: PlacesUtils.bookmarks.rootGuid,
+      url: "http://example.com",
+    }),
+    /Invalid value for property 'parentGuid'/,
+    "Should throw when inserting a bookmark into the root."
+  );
+  Assert.throws(() =>
+    PlacesUtils.bookmarks.insert({
+      parentGuid: PlacesUtils.bookmarks.rootGuid,
+      type: PlacesUtils.bookmarks.TYPE_FOLDER,
+    }),
+    /Invalid value for property 'parentGuid'/,
+    "Should throw when inserting a folder into the root."
+  );
+});
+
 add_task(async function long_title_trim() {
   let longtitle = "a";
   for (let i = 0; i < 4096; i++) {
diff --git a/toolkit/components/places/tests/bookmarks/test_bookmarks_remove.js b/toolkit/components/places/tests/bookmarks/test_bookmarks_remove.js
index e91790cf665b..c8e49a7fc482 100644
--- a/toolkit/components/places/tests/bookmarks/test_bookmarks_remove.js
+++ b/toolkit/components/places/tests/bookmarks/test_bookmarks_remove.js
@@ -71,14 +71,6 @@ add_task(async function remove_roots_fail() {
   }
 });
 
-add_task(async function remove_normal_folder_under_root_succeeds() {
-  let folder = await PlacesUtils.bookmarks.insert({ parentGuid: PlacesUtils.bookmarks.rootGuid,
-                                                    type: PlacesUtils.bookmarks.TYPE_FOLDER });
-  checkBookmarkObject(folder);
-  await PlacesUtils.bookmarks.remove(folder);
-  Assert.strictEqual((await PlacesUtils.bookmarks.fetch(folder.guid)), null);
-});
-
 add_task(async function remove_bookmark() {
   // When removing a bookmark we need to check the frecency. First we confirm
   // that there is a normal update when it is inserted.
diff --git a/toolkit/components/places/tests/bookmarks/test_bookmarks_update.js b/toolkit/components/places/tests/bookmarks/test_bookmarks_update.js
index 1636807cea47..6b2cf7bebe5e 100644
--- a/toolkit/components/places/tests/bookmarks/test_bookmarks_update.js
+++ b/toolkit/components/places/tests/bookmarks/test_bookmarks_update.js
@@ -88,7 +88,7 @@ add_task(async function move_roots_fail() {
     Assert.rejects(PlacesUtils.bookmarks.update({
       guid,
       index: -1,
-      parentGuid: PlacesUtils.bookmarks.rootGuid,
+      parentGuid: PlacesUtils.bookmarks.unfiledGuid,
     }), /It's not possible to move Places root folders\./,
     `Should reject when attempting to move ${guid}`);
   }
@@ -304,6 +304,36 @@ add_task(async function update_move_folder_into_descendant_throws() {
   }
 });
 
+add_task(async function update_move_into_root_folder_rejects() {
+  let folder = await PlacesUtils.bookmarks.insert({
+    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
+    type: PlacesUtils.bookmarks.TYPE_FOLDER
+  });
+  let bm = await PlacesUtils.bookmarks.insert({
+    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
+    url: "http://example.com/",
+    type: PlacesUtils.bookmarks.TYPE_BOOKMARK
+  });
+
+  Assert.throws(() =>
+    PlacesUtils.bookmarks.update({
+      guid: bm.guid,
+      index: -1,
+      parentGuid: PlacesUtils.bookmarks.rootGuid,
+    }), /Invalid value for property 'parentGuid'/,
+      "Should reject when attempting to move a bookmark into the root"
+  );
+
+  Assert.throws(() =>
+    PlacesUtils.bookmarks.update({
+      guid: folder.guid,
+      index: -1,
+      parentGuid: PlacesUtils.bookmarks.rootGuid,
+    }), /Invalid value for property 'parentGuid'/,
+      "Should reject when attempting to move a bookmark into the root"
+  );
+});
+
 add_task(async function update_move() {
   let parent = await PlacesUtils.bookmarks.insert({ parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                                                     type: PlacesUtils.bookmarks.TYPE_FOLDER }) ;
diff --git a/toolkit/components/places/tests/bookmarks/xpcshell.ini b/toolkit/components/places/tests/bookmarks/xpcshell.ini
index 0eae4e601397..0dab0b23e22a 100644
--- a/toolkit/components/places/tests/bookmarks/xpcshell.ini
+++ b/toolkit/components/places/tests/bookmarks/xpcshell.ini
@@ -10,8 +10,6 @@ skip-if = toolkit == 'android'
 [test_393498.js]
 [test_395593.js]
 [test_405938_restore_queries.js]
-[test_417228-exclude-from-backup.js]
-[test_417228-other-roots.js]
 [test_424958-json-quoted-folders.js]
 [test_448584.js]
 [test_458683.js]
diff --git a/toolkit/components/places/tests/queries/head_queries.js b/toolkit/components/places/tests/queries/head_queries.js
index e9af7337b15a..645034f983ae 100644
--- a/toolkit/components/places/tests/queries/head_queries.js
+++ b/toolkit/components/places/tests/queries/head_queries.js
@@ -217,7 +217,7 @@ function queryData(obj) {
   this.isTag = obj.isTag ? obj.isTag : false;
   this.tagArray = obj.tagArray ? obj.tagArray : null;
   this.isLivemark = obj.isLivemark ? obj.isLivemark : false;
-  this.parentGuid = obj.parentGuid || PlacesUtils.bookmarks.rootGuid;
+  this.parentGuid = obj.parentGuid || PlacesUtils.bookmarks.unfiledGuid;
   this.feedURI = obj.feedURI ? obj.feedURI : "";
   this.index = obj.index ? obj.index : PlacesUtils.bookmarks.DEFAULT_INDEX;
   this.isFolder = obj.isFolder ? obj.isFolder : false;
diff --git a/toolkit/components/places/tests/sync/test_sync_utils.js b/toolkit/components/places/tests/sync/test_sync_utils.js
index 0ce08dc22cdb..267dd182e712 100644
--- a/toolkit/components/places/tests/sync/test_sync_utils.js
+++ b/toolkit/components/places/tests/sync/test_sync_utils.js
@@ -2210,85 +2210,6 @@ add_task(async function test_pullChanges_restore_json_tracked() {
   await PlacesSyncUtils.bookmarks.reset();
 });
 
-add_task(async function test_pullChanges_custom_roots() {
-  await ignoreChangedRoots();
-
-  info("Append items to Places root");
-  let unsyncedGuids = await populateTree(PlacesUtils.bookmarks.rootGuid, {
-    kind: "folder",
-    title: "rootFolder",
-    children: [{
-      kind: "bookmark",
-      title: "childBmk",
-      url: "https://example.com",
-    }, {
-      kind: "folder",
-      title: "childFolder",
-      children: [{
-        kind: "bookmark",
-        title: "grandChildBmk",
-        url: "https://example.org",
-      }],
-    }],
-  }, {
-    kind: "bookmark",
-    title: "rootBmk",
-    url: "https://example.net",
-  });
-
-  info("Append items to menu");
-  let syncedGuids = await populateTree(PlacesUtils.bookmarks.menuGuid, {
-    kind: "folder",
-    title: "childFolder",
-    children: [{
-      kind: "bookmark",
-      title: "grandChildBmk",
-      url: "https://example.info",
-    }],
-  });
-
-  {
-    let newChanges = await PlacesSyncUtils.bookmarks.pullChanges();
-    deepEqual(Object.keys(newChanges).sort(), ["menu", syncedGuids.childFolder,
-      syncedGuids.grandChildBmk].sort(),
-      "Pulling changes should ignore custom roots");
-    await setChangesSynced(newChanges);
-  }
-
-  info("Append sibling to custom root");
-  {
-    let unsyncedSibling = await PlacesUtils.bookmarks.insert({
-      parentGuid: unsyncedGuids.rootFolder,
-      url: "https://example.club",
-    });
-    let changes = await PlacesSyncUtils.bookmarks.pullChanges();
-    deepEqual(changes, {}, `Pulling changes should ignore unsynced sibling ${
-      unsyncedSibling.guid}`);
-  }
-
-  info("Remove custom root");
-  {
-    await PlacesUtils.bookmarks.remove(unsyncedGuids.rootFolder);
-    let changes = await PlacesSyncUtils.bookmarks.pullChanges();
-    deepEqual(changes, {}, "Removing custom root should not write tombstone");
-  }
-
-  info("Append sibling to menu");
-  {
-    let syncedSibling = await PlacesUtils.bookmarks.insert({
-      parentGuid: PlacesUtils.bookmarks.menuGuid,
-      url: "https://example.ninja",
-    });
-    let changes = await PlacesSyncUtils.bookmarks.pullChanges();
-    deepEqual(Object.keys(changes).sort(), ["menu", syncedSibling.guid].sort(),
-      "Pulling changes should track synced sibling and parent");
-    await setChangesSynced(changes);
-  }
-
-  await PlacesUtils.bookmarks.eraseEverything();
-  await PlacesSyncUtils.bookmarks.reset();
-});
-
 add_task(async function test_pullChanges_tombstones() {
   await ignoreChangedRoots();
 
diff --git a/toolkit/components/places/tests/unit/test_async_transactions.js b/toolkit/components/places/tests/unit/test_async_transactions.js
index d35caa59916a..3634443720c9 100644
--- a/toolkit/components/places/tests/unit/test_async_transactions.js
+++ b/toolkit/components/places/tests/unit/test_async_transactions.js
@@ -8,7 +8,6 @@ const bmsvc    = PlacesUtils.bookmarks;
 const tagssvc  = PlacesUtils.tagging;
 const annosvc  = PlacesUtils.annotations;
 const PT       = PlacesTransactions;
-const rootGuid = PlacesUtils.bookmarks.rootGuid;
 const menuGuid = PlacesUtils.bookmarks.menuGuid;
 
 Cu.importGlobalProperties(["URL"]);
@@ -514,7 +513,7 @@ add_task(async function test_new_folder_with_children() {
 });
 
 add_task(async function test_new_bookmark() {
-  let bm_info = { parentGuid: rootGuid,
+  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                   url:        NetUtil.newURI("http://test_create_item.com"),
                   index:      bmStartIndex,
                   title:      "Test creating an item" };
@@ -976,7 +975,7 @@ add_task(async function test_creating_and_removing_a_separator() {
 add_task(async function test_add_and_remove_livemark() {
   let createLivemarkTxn = PT.NewLivemark(
     { feedUrl: NetUtil.newURI("http://test.remove.livemark"),
-      parentGuid: rootGuid,
+      parentGuid: PlacesUtils.bookmarks.unfiledGuid,
       title: "Test Remove Livemark" });
   let guid = await createLivemarkTxn.transact();
   let originalInfo = await PlacesUtils.promiseBookmarksTree(guid);
@@ -1018,7 +1017,7 @@ add_task(async function test_add_and_remove_livemark() {
 });
 
 add_task(async function test_edit_title() {
-  let bm_info = { parentGuid: rootGuid,
+  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                   url:        NetUtil.newURI("http://test_create_item.com"),
                   title:      "Original Title" };
 
@@ -1056,7 +1055,7 @@ add_task(async function test_edit_title() {
 add_task(async function test_edit_url() {
   let oldURI = NetUtil.newURI("http://old.test_editing_item_uri.com/");
   let newURI = NetUtil.newURI("http://new.test_editing_item_uri.com/");
-  let bm_info = { parentGuid: rootGuid, url: oldURI, tags: ["TestTag"] };
+  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid, url: oldURI, tags: ["TestTag"] };
   function ensureURIAndTags(aPreChangeURI, aPostChangeURI, aOLdURITagsPreserved) {
     ensureItemsChanged({ guid: bm_info.guid,
                          property: "uri",
@@ -1118,7 +1117,7 @@ add_task(async function test_edit_url() {
 });
 
 add_task(async function test_edit_keyword() {
-  let bm_info = { parentGuid: rootGuid,
+  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                   url: NetUtil.newURI("http://test.edit.keyword") };
   const KEYWORD = "test_keyword";
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
@@ -1162,7 +1161,7 @@ add_task(async function test_edit_keyword() {
 });
 
 add_task(async function test_edit_keyword_null_postData() {
-  let bm_info = { parentGuid: rootGuid,
+  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                   url: NetUtil.newURI("http://test.edit.keyword") };
   const KEYWORD = "test_keyword";
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
@@ -1206,7 +1205,7 @@ add_task(async function test_edit_keyword_null_postData() {
 });
 
 add_task(async function test_edit_specific_keyword() {
-  let bm_info = { parentGuid: rootGuid,
+  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                   url: NetUtil.newURI("http://test.edit.keyword") };
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
   function ensureKeywordChange(aCurrentKeyword = "", aPreviousKeyword = "") {
@@ -1270,9 +1269,9 @@ add_task(async function test_edit_specific_keyword() {
 add_task(async function test_tag_uri() {
   // This also tests passing uri specs.
   let bm_info_a = { url: "http://bookmarked.uri",
-                    parentGuid: rootGuid };
+                    parentGuid: PlacesUtils.bookmarks.unfiledGuid };
   let bm_info_b = { url: NetUtil.newURI("http://bookmarked2.uri"),
-                    parentGuid: rootGuid };
+                    parentGuid: PlacesUtils.bookmarks.unfiledGuid };
   let unbookmarked_uri = NetUtil.newURI("http://un.bookmarked.uri");
 
   await PT.batch(async function() {
@@ -1338,10 +1337,10 @@ add_task(async function test_tag_uri() {
 
 add_task(async function test_untag_uri() {
   let bm_info_a = { url: NetUtil.newURI("http://bookmarked.uri"),
-                    parentGuid: rootGuid,
+                    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                     tags: ["A", "B"] };
   let bm_info_b = { url: NetUtil.newURI("http://bookmarked2.uri"),
-                    parentGuid: rootGuid,
+                    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                     tag: "B" };
 
   await PT.batch(async function() {
@@ -1413,7 +1412,7 @@ add_task(async function test_untag_uri() {
 
 add_task(async function test_annotate() {
   let bm_info = { url: NetUtil.newURI("http://test.item.annotation"),
-                  parentGuid: rootGuid };
+                  parentGuid: PlacesUtils.bookmarks.unfiledGuid };
   let anno_info = { name: "TestAnno", value: "TestValue" };
   function ensureAnnoState(aSet) {
     ensureAnnotationsSet(bm_info.guid,
@@ -1558,7 +1557,7 @@ add_task(async function test_sort_folder_by_name() {
 add_task(async function test_livemark_txns() {
   let livemark_info =
     { feedUrl: NetUtil.newURI("http://test.feed.uri"),
-      parentGuid: rootGuid,
+      parentGuid: PlacesUtils.bookmarks.unfiledGuid,
       title: "Test Livemark" };
   function ensureLivemarkAdded() {
     ensureItemsAdded({ guid:       livemark_info.guid,
@@ -1606,7 +1605,9 @@ add_task(async function test_livemark_txns() {
 
 add_task(async function test_copy() {
   async function duplicate_and_test(aOriginalGuid) {
-    let txn = PT.Copy({ guid: aOriginalGuid, newParentGuid: rootGuid });
+    let txn = PT.Copy({
+      guid: aOriginalGuid, newParentGuid: PlacesUtils.bookmarks.unfiledGuid
+    });
     let duplicateGuid = await txn.transact();
     let originalInfo = await PlacesUtils.promiseBookmarksTree(aOriginalGuid);
     let duplicateInfo = await PlacesUtils.promiseBookmarksTree(duplicateGuid);
@@ -1645,12 +1646,15 @@ add_task(async function test_copy() {
 
   // Test duplicating leafs (bookmark, separator, empty folder)
   PT.NewBookmark({ url: new URL("http://test.item.duplicate"),
-                   parentGuid: rootGuid,
+                   parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                    annos: [{ name: "Anno", value: "AnnoValue"}] });
-  let sepTxn = PT.NewSeparator({ parentGuid: rootGuid, index: 1 });
+  let sepTxn = PT.NewSeparator({
+    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
+    index: 1
+  });
   let livemarkTxn = PT.NewLivemark(
     { feedUrl: new URL("http://test.feed.uri"),
-      parentGuid: rootGuid,
+      parentGuid: PlacesUtils.bookmarks.unfiledGuid,
       title: "Test Livemark", index: 1 });
   let emptyFolderTxn = PT.NewFolder(createTestFolderInfo());
   for (let txn of [livemarkTxn, sepTxn, emptyFolderTxn]) {
@@ -1730,13 +1734,13 @@ add_task(async function test_copy_excluding_annotations() {
 
   let excluding_a_dupeGuid =
     await PT.Copy({ guid: folderGuid,
-                    newParentGuid: rootGuid,
+                    newParentGuid: PlacesUtils.bookmarks.unfiledGuid,
                     excludingAnnotation: "a" }).transact();
   await ensureAnnosSet(excluding_a_dupeGuid, "b", "c");
 
   let excluding_ac_dupeGuid =
     await PT.Copy({ guid: folderGuid,
-                    newParentGuid: rootGuid,
+                    newParentGuid: PlacesUtils.bookmarks.unfiledGuid,
                     excludingAnnotations: ["a", "c"] }).transact();
   await ensureAnnosSet(excluding_ac_dupeGuid, "b");
 
@@ -1749,7 +1753,7 @@ add_task(async function test_copy_excluding_annotations() {
 
 add_task(async function test_invalid_uri_spec_throws() {
   Assert.throws(() =>
-    PT.NewBookmark({ parentGuid: rootGuid,
+    PT.NewBookmark({ parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                      url:        "invalid uri spec",
                      title:      "test bookmark" }));
   Assert.throws(() =>

From d7bfe2db7904a26bacac3570af944594ccd60416 Mon Sep 17 00:00:00 2001
From: Mark Banner <standard8@mozilla.com>
Date: Thu, 8 Mar 2018 10:07:01 +0000
Subject: [PATCH 15/50] Bug 1443835 - Stop using Netutil.newURI everywhere in
 test_async_transactions.js. r=mak

MozReview-Commit-ID: 3QOXMq8G1gP

--HG--
extra : rebase_source : 5c5180fd3760fc43b470c7ac5b49602c545b5a26
---
 .../tests/unit/test_async_transactions.js     | 106 ++++++++++--------
 1 file changed, 57 insertions(+), 49 deletions(-)

diff --git a/toolkit/components/places/tests/unit/test_async_transactions.js b/toolkit/components/places/tests/unit/test_async_transactions.js
index 3634443720c9..079e9cf47b4b 100644
--- a/toolkit/components/places/tests/unit/test_async_transactions.js
+++ b/toolkit/components/places/tests/unit/test_async_transactions.js
@@ -180,7 +180,8 @@ function ensureItemsAdded(...items) {
         Assert.equal(info[propName], item[propName]);
     }
     if ("url" in item)
-      Assert.ok(info.url.equals(item.url));
+      Assert.ok(info.url.equals(Services.io.newURI(item.url)),
+        "Should have the correct url");
   }
 
   Assert.equal(observer.itemsAdded.size, expectedResultsCount,
@@ -263,7 +264,7 @@ function ensureTimestampsUpdated(aGuid, aCheckDateAdded = false) {
 }
 
 function ensureTagsForURI(aURI, aTags) {
-  let tagsSet = tagssvc.getTagsForURI(aURI);
+  let tagsSet = tagssvc.getTagsForURI(Services.io.newURI(aURI));
   Assert.equal(tagsSet.length, aTags.length);
   Assert.ok(aTags.every( t => tagsSet.includes(t)));
 }
@@ -514,7 +515,7 @@ add_task(async function test_new_folder_with_children() {
 
 add_task(async function test_new_bookmark() {
   let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
-                  url:        NetUtil.newURI("http://test_create_item.com"),
+                  url:        "http://test_create_item.com",
                   index:      bmStartIndex,
                   title:      "Test creating an item" };
 
@@ -552,7 +553,7 @@ add_task(async function test_new_bookmark() {
 
 add_task(async function test_merge_create_folder_and_item() {
   let folder_info = createTestFolderInfo();
-  let bm_info = { url: NetUtil.newURI("http://test_create_item_to_folder.com"),
+  let bm_info = { url: "http://test_create_item_to_folder.com",
                   title: "Test Bookmark",
                   index: bmStartIndex };
 
@@ -590,9 +591,9 @@ add_task(async function test_merge_create_folder_and_item() {
 
 add_task(async function test_move_items_to_folder() {
   let folder_a_info = createTestFolderInfo("Folder A");
-  let bkm_a_info = { url: new URL("http://test_move_items.com"),
+  let bkm_a_info = { url: "http://test_move_items.com",
                      title: "Bookmark A" };
-  let bkm_b_info = { url: NetUtil.newURI("http://test_move_items.com"),
+  let bkm_b_info = { url: "http://test_move_items.com",
                      title: "Bookmark B" };
 
   // Test moving items within the same folder.
@@ -791,7 +792,7 @@ add_task(async function test_remove_folder() {
 });
 
 add_task(async function test_add_and_remove_bookmarks_with_additional_info() {
-  const testURI = NetUtil.newURI("http://add.remove.tag");
+  const testURI = "http://add.remove.tag";
   const TAG_1 = "TestTag1";
   const TAG_2 = "TestTag2";
   const ANNO = { name: "TestAnno", value: "TestAnnoValue" };
@@ -974,7 +975,7 @@ add_task(async function test_creating_and_removing_a_separator() {
 
 add_task(async function test_add_and_remove_livemark() {
   let createLivemarkTxn = PT.NewLivemark(
-    { feedUrl: NetUtil.newURI("http://test.remove.livemark"),
+    { feedUrl: "http://test.remove.livemark",
       parentGuid: PlacesUtils.bookmarks.unfiledGuid,
       title: "Test Remove Livemark" });
   let guid = await createLivemarkTxn.transact();
@@ -1017,9 +1018,11 @@ add_task(async function test_add_and_remove_livemark() {
 });
 
 add_task(async function test_edit_title() {
-  let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
-                  url:        NetUtil.newURI("http://test_create_item.com"),
-                  title:      "Original Title" };
+  let bm_info = {
+    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
+    url: "http://test_create_item.com",
+    title: "Original Title"
+  };
 
   function ensureTitleChange(aCurrentTitle) {
     ensureItemsChanged({ guid: bm_info.guid,
@@ -1053,13 +1056,13 @@ add_task(async function test_edit_title() {
 });
 
 add_task(async function test_edit_url() {
-  let oldURI = NetUtil.newURI("http://old.test_editing_item_uri.com/");
-  let newURI = NetUtil.newURI("http://new.test_editing_item_uri.com/");
+  let oldURI = "http://old.test_editing_item_uri.com/";
+  let newURI = "http://new.test_editing_item_uri.com/";
   let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid, url: oldURI, tags: ["TestTag"] };
   function ensureURIAndTags(aPreChangeURI, aPostChangeURI, aOLdURITagsPreserved) {
     ensureItemsChanged({ guid: bm_info.guid,
                          property: "uri",
-                         newValue: aPostChangeURI.spec });
+                         newValue: aPostChangeURI });
     ensureTagsForURI(aPostChangeURI, bm_info.tags);
     ensureTagsForURI(aPreChangeURI, aOLdURITagsPreserved ? bm_info.tags : []);
   }
@@ -1118,7 +1121,7 @@ add_task(async function test_edit_url() {
 
 add_task(async function test_edit_keyword() {
   let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
-                  url: NetUtil.newURI("http://test.edit.keyword") };
+                  url: "http://test.edit.keyword/" };
   const KEYWORD = "test_keyword";
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
   function ensureKeywordChange(aCurrentKeyword = "") {
@@ -1133,7 +1136,7 @@ add_task(async function test_edit_keyword() {
   await PT.EditKeyword({ guid: bm_info.guid, keyword: KEYWORD, postData: "postData" }).transact();
   ensureKeywordChange(KEYWORD);
   let entry = await PlacesUtils.keywords.fetch(KEYWORD);
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData");
 
   observer.reset();
@@ -1146,7 +1149,7 @@ add_task(async function test_edit_keyword() {
   await PT.redo();
   ensureKeywordChange(KEYWORD);
   entry = await PlacesUtils.keywords.fetch(KEYWORD);
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData");
 
   // Cleanup
@@ -1162,7 +1165,7 @@ add_task(async function test_edit_keyword() {
 
 add_task(async function test_edit_keyword_null_postData() {
   let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
-                  url: NetUtil.newURI("http://test.edit.keyword") };
+                  url: "http://test.edit.keyword/" };
   const KEYWORD = "test_keyword";
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
   function ensureKeywordChange(aCurrentKeyword = "") {
@@ -1177,7 +1180,7 @@ add_task(async function test_edit_keyword_null_postData() {
   await PT.EditKeyword({ guid: bm_info.guid, keyword: KEYWORD, postData: null }).transact();
   ensureKeywordChange(KEYWORD);
   let entry = await PlacesUtils.keywords.fetch(KEYWORD);
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, null);
 
   observer.reset();
@@ -1190,7 +1193,7 @@ add_task(async function test_edit_keyword_null_postData() {
   await PT.redo();
   ensureKeywordChange(KEYWORD);
   entry = await PlacesUtils.keywords.fetch(KEYWORD);
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, null);
 
   // Cleanup
@@ -1206,7 +1209,7 @@ add_task(async function test_edit_keyword_null_postData() {
 
 add_task(async function test_edit_specific_keyword() {
   let bm_info = { parentGuid: PlacesUtils.bookmarks.unfiledGuid,
-                  url: NetUtil.newURI("http://test.edit.keyword") };
+                  url: "http://test.edit.keyword/" };
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
   function ensureKeywordChange(aCurrentKeyword = "", aPreviousKeyword = "") {
     ensureItemsChanged({ guid: bm_info.guid,
@@ -1215,18 +1218,26 @@ add_task(async function test_edit_specific_keyword() {
                        });
   }
 
-  await PlacesUtils.keywords.insert({ keyword: "kw1", url: bm_info.url.spec, postData: "postData1" });
-  await PlacesUtils.keywords.insert({ keyword: "kw2", url: bm_info.url.spec, postData: "postData2" });
+  await PlacesUtils.keywords.insert({
+    keyword: "kw1",
+    url: bm_info.url,
+    postData: "postData1"
+  });
+  await PlacesUtils.keywords.insert({
+    keyword: "kw2",
+    url: bm_info.url,
+    postData: "postData2"
+  });
   bm_info.guid = await PT.NewBookmark(bm_info).transact();
 
   observer.reset();
   await PT.EditKeyword({ guid: bm_info.guid, keyword: "keyword", oldKeyword: "kw2" }).transact();
   ensureKeywordChange("keyword", "kw2");
   let entry = await PlacesUtils.keywords.fetch("kw1");
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData1");
   entry = await PlacesUtils.keywords.fetch("keyword");
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData2");
   entry = await PlacesUtils.keywords.fetch("kw2");
   Assert.equal(entry, null);
@@ -1235,10 +1246,10 @@ add_task(async function test_edit_specific_keyword() {
   await PT.undo();
   ensureKeywordChange("kw2", "keyword");
   entry = await PlacesUtils.keywords.fetch("kw1");
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData1");
   entry = await PlacesUtils.keywords.fetch("kw2");
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData2");
   entry = await PlacesUtils.keywords.fetch("keyword");
   Assert.equal(entry, null);
@@ -1247,10 +1258,10 @@ add_task(async function test_edit_specific_keyword() {
   await PT.redo();
   ensureKeywordChange("keyword", "kw2");
   entry = await PlacesUtils.keywords.fetch("kw1");
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData1");
   entry = await PlacesUtils.keywords.fetch("keyword");
-  Assert.equal(entry.url.href, bm_info.url.spec);
+  Assert.equal(entry.url.href, bm_info.url);
   Assert.equal(entry.postData, "postData2");
   entry = await PlacesUtils.keywords.fetch("kw2");
   Assert.equal(entry, null);
@@ -1270,9 +1281,9 @@ add_task(async function test_tag_uri() {
   // This also tests passing uri specs.
   let bm_info_a = { url: "http://bookmarked.uri",
                     parentGuid: PlacesUtils.bookmarks.unfiledGuid };
-  let bm_info_b = { url: NetUtil.newURI("http://bookmarked2.uri"),
+  let bm_info_b = { url: "http://bookmarked2.uri",
                     parentGuid: PlacesUtils.bookmarks.unfiledGuid };
-  let unbookmarked_uri = NetUtil.newURI("http://un.bookmarked.uri");
+  let unbookmarked_uri = "http://un.bookmarked.uri";
 
   await PT.batch(async function() {
     bm_info_a.guid = await PT.NewBookmark(bm_info_a).transact();
@@ -1283,9 +1294,6 @@ add_task(async function test_tag_uri() {
     let urls = "url" in aInfo ? [aInfo.url] : aInfo.urls;
     let tags = "tag" in aInfo ? [aInfo.tag] : aInfo.tags;
 
-    let ensureURI = url => typeof(url) == "string" ? NetUtil.newURI(url) : url;
-    urls = urls.map(ensureURI);
-
     let tagWillAlsoBookmark = new Set();
     for (let url of urls) {
       if (!(await bmsvc.fetch({ url }))) {
@@ -1336,10 +1344,10 @@ add_task(async function test_tag_uri() {
 });
 
 add_task(async function test_untag_uri() {
-  let bm_info_a = { url: NetUtil.newURI("http://bookmarked.uri"),
+  let bm_info_a = { url: "http://bookmarked.uri",
                     parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                     tags: ["A", "B"] };
-  let bm_info_b = { url: NetUtil.newURI("http://bookmarked2.uri"),
+  let bm_info_b = { url: "http://bookmarked2.uri",
                     parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                     tag: "B" };
 
@@ -1352,7 +1360,7 @@ add_task(async function test_untag_uri() {
 
   async function doTest(aInfo) {
     let urls, tagsRemoved;
-    if (aInfo instanceof Ci.nsIURI) {
+    if (typeof(aInfo) == "string") {
       urls = [aInfo];
       tagsRemoved = [];
     } else if (Array.isArray(aInfo)) {
@@ -1365,7 +1373,7 @@ add_task(async function test_untag_uri() {
 
     let preRemovalTags = new Map();
     for (let url of urls) {
-      preRemovalTags.set(url, tagssvc.getTagsForURI(url));
+      preRemovalTags.set(url, tagssvc.getTagsForURI(Services.io.newURI(url)));
     }
 
     function ensureTagsSet() {
@@ -1411,7 +1419,7 @@ add_task(async function test_untag_uri() {
 });
 
 add_task(async function test_annotate() {
-  let bm_info = { url: NetUtil.newURI("http://test.item.annotation"),
+  let bm_info = { url: "http://test.item.annotation",
                   parentGuid: PlacesUtils.bookmarks.unfiledGuid };
   let anno_info = { name: "TestAnno", value: "TestValue" };
   function ensureAnnoState(aSet) {
@@ -1512,7 +1520,7 @@ add_task(async function test_annotate_multiple() {
 add_task(async function test_sort_folder_by_name() {
   let folder_info = createTestFolderInfo();
 
-  let url = NetUtil.newURI("http://sort.by.name/");
+  let url = "http://sort.by.name/";
   let preSep =  ["3", "2", "1"].map(i => ({ title: i, url }));
   let sep = {};
   let postSep = ["c", "b", "a"].map(l => ({ title: l, url }));
@@ -1556,7 +1564,7 @@ add_task(async function test_sort_folder_by_name() {
 
 add_task(async function test_livemark_txns() {
   let livemark_info =
-    { feedUrl: NetUtil.newURI("http://test.feed.uri"),
+    { feedUrl: "http://test.feed.uri/",
       parentGuid: PlacesUtils.bookmarks.unfiledGuid,
       title: "Test Livemark" };
   function ensureLivemarkAdded() {
@@ -1565,10 +1573,10 @@ add_task(async function test_livemark_txns() {
                        parentGuid: livemark_info.parentGuid,
                        itemType:   bmsvc.TYPE_FOLDER });
     let annos = [{ name:  PlacesUtils.LMANNO_FEEDURI,
-                   value: livemark_info.feedUrl.spec }];
+                   value: livemark_info.feedUrl }];
     if ("siteUrl" in livemark_info) {
       annos.push({ name: PlacesUtils.LMANNO_SITEURI,
-                   value: livemark_info.siteUrl.spec });
+                   value: livemark_info.siteUrl });
     }
     ensureAnnotationsSet(livemark_info.guid, annos);
   }
@@ -1595,7 +1603,7 @@ add_task(async function test_livemark_txns() {
   }
 
   await _testDoUndoRedoUndo();
-  livemark_info.siteUrl = NetUtil.newURI("http://feed.site.uri");
+  livemark_info.siteUrl = "http://feed.site.uri/";
   await _testDoUndoRedoUndo();
 
   // Cleanup
@@ -1645,7 +1653,7 @@ add_task(async function test_copy() {
   });
 
   // Test duplicating leafs (bookmark, separator, empty folder)
-  PT.NewBookmark({ url: new URL("http://test.item.duplicate"),
+  PT.NewBookmark({ url: "http://test.item.duplicate",
                    parentGuid: PlacesUtils.bookmarks.unfiledGuid,
                    annos: [{ name: "Anno", value: "AnnoValue"}] });
   let sepTxn = PT.NewSeparator({
@@ -1653,7 +1661,7 @@ add_task(async function test_copy() {
     index: 1
   });
   let livemarkTxn = PT.NewLivemark(
-    { feedUrl: new URL("http://test.feed.uri"),
+    { feedUrl: "http://test.feed.uri",
       parentGuid: PlacesUtils.bookmarks.unfiledGuid,
       title: "Test Livemark", index: 1 });
   let emptyFolderTxn = PT.NewFolder(createTestFolderInfo());
@@ -1669,12 +1677,12 @@ add_task(async function test_copy() {
       await PT.NewFolder({ parentGuid: folderGuid,
                            title: "Nested Folder" }).transact();
     // Insert a bookmark under the nested folder.
-    await PT.NewBookmark({ url: new URL("http://nested.nested.bookmark"),
+    await PT.NewBookmark({ url: "http://nested.nested.bookmark",
                            parentGuid: nestedFolderGuid }).transact();
     // Insert a separator below the nested folder
     await PT.NewSeparator({ parentGuid: folderGuid }).transact();
     // And another bookmark.
-    await PT.NewBookmark({ url: new URL("http://nested.bookmark"),
+    await PT.NewBookmark({ url: "http://nested.bookmark",
                            parentGuid: folderGuid }).transact();
     return folderGuid;
   });
@@ -1816,7 +1824,7 @@ add_task(async function test_remove_multiple() {
     guids.push(folderGuid);
 
     let bmGuid =
-      await PT.NewBookmark({ url: new URL("http://test.bookmark.removed"),
+      await PT.NewBookmark({ url: "http://test.bookmark.removed",
                              parentGuid: menuGuid }).transact();
     guids.push(bmGuid);
   });

From 61992349bee2be155c30d7155dccf21cc9d9d813 Mon Sep 17 00:00:00 2001
From: Mike Ratcliffe <mratcliffe@mozilla.com>
Date: Fri, 9 Mar 2018 13:55:22 +0000
Subject: [PATCH 16/50] Bug 1444106 - Add test for rapid addition and removal
 of items in the storage inspector r=ochameau

MozReview-Commit-ID: 5sM12SBiBSF

--HG--
extra : rebase_source : 31140fa6c45471942131c9cf8bb8a78cdf226118
---
 devtools/client/storage/test/browser.ini      |  2 ++
 ...r_storage_localstorage_rapid_add_remove.js | 34 +++++++++++++++++++
 devtools/client/storage/test/head.js          | 11 ++++++
 .../client/storage/test/storage-blank.html    |  9 +++++
 4 files changed, 56 insertions(+)
 create mode 100644 devtools/client/storage/test/browser_storage_localstorage_rapid_add_remove.js
 create mode 100644 devtools/client/storage/test/storage-blank.html

diff --git a/devtools/client/storage/test/browser.ini b/devtools/client/storage/test/browser.ini
index 582490788c55..8c5795ec3c62 100644
--- a/devtools/client/storage/test/browser.ini
+++ b/devtools/client/storage/test/browser.ini
@@ -2,6 +2,7 @@
 tags = devtools
 subsuite = devtools
 support-files =
+  storage-blank.html
   storage-cache-error.html
   storage-complex-values.html
   storage-cookies.html
@@ -55,6 +56,7 @@ tags = usercontextid
 [browser_storage_localstorage_add.js]
 [browser_storage_localstorage_edit.js]
 [browser_storage_localstorage_error.js]
+[browser_storage_localstorage_rapid_add_remove.js]
 [browser_storage_overflow.js]
 [browser_storage_search.js]
 [browser_storage_search_keyboard_trap.js]
diff --git a/devtools/client/storage/test/browser_storage_localstorage_rapid_add_remove.js b/devtools/client/storage/test/browser_storage_localstorage_rapid_add_remove.js
new file mode 100644
index 000000000000..af3f8ca85387
--- /dev/null
+++ b/devtools/client/storage/test/browser_storage_localstorage_rapid_add_remove.js
@@ -0,0 +1,34 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* import-globals-from head.js */
+
+// Basic test to check the rapid adding and removing of localStorage entries.
+
+"use strict";
+
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-blank.html");
+  yield selectTreeItem(["localStorage", "http://test1.example.org"]);
+
+  ok(isTableEmpty(), "Table empty on init");
+
+  for (let i = 0; i < 10; i++) {
+    yield addRemove(`test${i}`);
+  }
+
+  yield finishTests();
+});
+
+function* addRemove(name) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, name, innerName => {
+    content.localStorage.setItem(innerName, "true");
+    content.localStorage.removeItem(innerName);
+  });
+
+  info("Waiting for store objects to be changed");
+  yield gUI.once("store-objects-edit");
+
+  ok(isTableEmpty(), `Table empty after rapid add/remove of "${name}"`);
+}
diff --git a/devtools/client/storage/test/head.js b/devtools/client/storage/test/head.js
index 57c2c6934a55..3355c077d69a 100644
--- a/devtools/client/storage/test/head.js
+++ b/devtools/client/storage/test/head.js
@@ -640,6 +640,17 @@ function getRowCells(id, includeHidden = false) {
   return cells;
 }
 
+/**
+ * Check for an empty table.
+ */
+function isTableEmpty() {
+  let doc = gPanelWindow.document;
+  let table = gUI.table;
+  let cells = doc.querySelectorAll(".table-widget-column#" + table.uniqueId +
+                                   " .table-widget-cell");
+  return cells.length === 0;
+}
+
 /**
  * Get available ids... useful for error reporting.
  */
diff --git a/devtools/client/storage/test/storage-blank.html b/devtools/client/storage/test/storage-blank.html
new file mode 100644
index 000000000000..81342ed69028
--- /dev/null
+++ b/devtools/client/storage/test/storage-blank.html
@@ -0,0 +1,9 @@
+<!doctype html>
+<html>
+  <head>
+    <meta charset="utf-8" />
+  </head>
+  <body>
+    <h2>storage-blank.html</h2>
+  </body>
+</html>

From 6b7caea7612f83df34208c6545208f902cc24644 Mon Sep 17 00:00:00 2001
From: Michael Ratcliffe <mratcliffe@mozilla.com>
Date: Fri, 9 Mar 2018 17:21:03 +0000
Subject: [PATCH 17/50] Bug 1444414 - Remove all CPOWs from storage inspector
 tests r=nchevobbe

MozReview-Commit-ID: JGuYffnzXDb

--HG--
extra : rebase_source : 8ad2094589934cef063f4a2d346ff0433f174158
---
 ...browser_storage_dynamic_updates_cookies.js | 30 ++++++++++++++-----
 ...er_storage_dynamic_updates_localStorage.js | 22 ++++++++++++--
 ..._storage_dynamic_updates_sessionStorage.js | 24 ++++++++++++---
 devtools/client/storage/test/head.js          |  9 ++----
 4 files changed, 64 insertions(+), 21 deletions(-)

diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
index 124f7f0f1284..de0e51b56c63 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
@@ -52,7 +52,7 @@ add_task(function* () {
   ]);
   checkCell(c1id, "value", "1.2.3.4.5.6.7");
 
-  gWindow.addCookie("c1", '{"foo": 4,"bar":6}', "/browser");
+  yield addCookie("c1", '{"foo": 4,"bar":6}', "/browser");
   yield gUI.once("store-objects-edit");
 
   yield findVariableViewProperties(finalValue[0], false);
@@ -70,7 +70,7 @@ add_task(function* () {
   checkCell(c1id, "value", '{"foo": 4,"bar":6}');
 
   // Add a new entry
-  gWindow.addCookie("c3", "booyeah");
+  yield addCookie("c3", "booyeah");
 
   yield gUI.once("store-objects-edit");
 
@@ -90,7 +90,7 @@ add_task(function* () {
   checkCell(c3id, "value", "booyeah");
 
   // Add another
-  gWindow.addCookie("c4", "booyeah");
+  yield addCookie("c4", "booyeah");
 
   yield gUI.once("store-objects-edit");
 
@@ -112,7 +112,7 @@ add_task(function* () {
   checkCell(c4id, "value", "booyeah");
 
   // Removing cookies
-  gWindow.removeCookie("c1", "/browser");
+  yield removeCookie("c1", "/browser");
 
   yield gUI.once("store-objects-edit");
 
@@ -135,7 +135,7 @@ add_task(function* () {
   yield findVariableViewProperties([{name: "c2", value: "foobar"}]);
 
   // Keep deleting till no rows
-  gWindow.removeCookie("c3");
+  yield removeCookie("c3");
 
   yield gUI.once("store-objects-edit");
 
@@ -153,7 +153,7 @@ add_task(function* () {
   // Check if next element's value is visible in sidebar
   yield findVariableViewProperties([{name: "c2", value: "foobar"}]);
 
-  gWindow.removeCookie("c2", "/browser");
+  yield removeCookie("c2", "/browser");
 
   yield gUI.once("store-objects-edit");
 
@@ -170,7 +170,7 @@ add_task(function* () {
   // Check if next element's value is visible in sidebar
   yield findVariableViewProperties([{name: "c4", value: "booyeah"}]);
 
-  gWindow.removeCookie("c4");
+  yield removeCookie("c4");
 
   yield gUI.once("store-objects-edit");
 
@@ -182,3 +182,19 @@ add_task(function* () {
 
   yield finishTests();
 });
+
+function* addCookie(name, value, path) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, [name, value, path],
+    ([nam, valu, pat]) => {
+      content.wrappedJSObject.addCookie(nam, valu, pat);
+    }
+  );
+}
+
+function* removeCookie(name, path) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, [name, path],
+    ([nam, pat]) => {
+      content.wrappedJSObject.removeCookie(nam, pat);
+    }
+  );
+}
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
index 576aadf56134..074047e2c037 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
@@ -20,7 +20,7 @@ add_task(function* () {
     ],
   ]);
 
-  gWindow.localStorage.removeItem("ls4");
+  yield removeLocalStorageItem("ls4");
 
   yield gUI.once("store-objects-edit");
 
@@ -31,7 +31,7 @@ add_task(function* () {
     ],
   ]);
 
-  gWindow.localStorage.setItem("ls4", "again");
+  yield setLocalStorageItem("ls4", "again");
 
   yield gUI.once("store-objects-edit");
 
@@ -42,7 +42,7 @@ add_task(function* () {
     ],
   ]);
   // Updating a row
-  gWindow.localStorage.setItem("ls2", "ls2-changed");
+  yield setLocalStorageItem("ls2", "ls2-changed");
 
   yield gUI.once("store-objects-edit");
 
@@ -64,3 +64,19 @@ add_task(function* () {
 
   yield finishTests();
 });
+
+function* setLocalStorageItem(key, value) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, [key, value],
+    ([innerKey, innerValue]) => {
+      content.wrappedJSObject.localStorage.setItem(innerKey, innerValue);
+    }
+  );
+}
+
+function* removeLocalStorageItem(key) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, key,
+    innerKey => {
+      content.wrappedJSObject.localStorage.removeItem(innerKey);
+    }
+  );
+}
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
index 4c07a2dd1e8d..75b0056c5ec3 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
@@ -20,7 +20,7 @@ add_task(function* () {
     ],
   ]);
 
-  gWindow.sessionStorage.setItem("ss4", "new-item");
+  yield setSessionStorageItem("ss4", "new-item");
 
   yield gUI.once("store-objects-edit");
 
@@ -33,11 +33,11 @@ add_task(function* () {
 
   // deleting item
 
-  gWindow.sessionStorage.removeItem("ss3");
+  yield removeSessionStorageItem("ss3");
 
   yield gUI.once("store-objects-edit");
 
-  gWindow.sessionStorage.removeItem("ss1");
+  yield removeSessionStorageItem("ss1");
 
   yield gUI.once("store-objects-edit");
 
@@ -55,7 +55,7 @@ add_task(function* () {
   // Checking for correct value in sidebar before update
   yield findVariableViewProperties([{name: "ss2", value: "foobar"}]);
 
-  gWindow.sessionStorage.setItem("ss2", "changed=ss2");
+  yield setSessionStorageItem("ss2", "changed=ss2");
 
   yield gUI.once("sidebar-updated");
 
@@ -79,3 +79,19 @@ add_task(function* () {
 
   yield finishTests();
 });
+
+function* setSessionStorageItem(key, value) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, [key, value],
+    ([innerKey, innerValue]) => {
+      content.wrappedJSObject.sessionStorage.setItem(innerKey, innerValue);
+    }
+  );
+}
+
+function* removeSessionStorageItem(key) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, key,
+    innerKey => {
+      content.wrappedJSObject.sessionStorage.removeItem(innerKey);
+    }
+  );
+}
diff --git a/devtools/client/storage/test/head.js b/devtools/client/storage/test/head.js
index 3355c077d69a..0e7a44969c1a 100644
--- a/devtools/client/storage/test/head.js
+++ b/devtools/client/storage/test/head.js
@@ -30,7 +30,7 @@ const ALT_DOMAIN_SECURED = "https://sectest1.example.org:443/" + PATH;
 // devtools/client/storage/ui.js and devtools/server/tests/browser/head.js
 const SEPARATOR_GUID = "{9d414cc5-8319-0a04-0586-c0a6ae01670a}";
 
-var gToolbox, gPanelWindow, gWindow, gUI;
+var gToolbox, gPanelWindow, gUI;
 
 // Services.prefs.setBoolPref(DUMPEMIT_PREF, true);
 // Services.prefs.setBoolPref(DEBUGGERLOG_PREF, true);
@@ -38,7 +38,7 @@ var gToolbox, gPanelWindow, gWindow, gUI;
 Services.prefs.setBoolPref(STORAGE_PREF, true);
 Services.prefs.setBoolPref(CACHES_ON_HTTP_PREF, true);
 registerCleanupFunction(() => {
-  gToolbox = gPanelWindow = gWindow = gUI = null;
+  gToolbox = gPanelWindow = gUI = null;
   Services.prefs.clearUserPref(CACHES_ON_HTTP_PREF);
   Services.prefs.clearUserPref(DEBUGGERLOG_PREF);
   Services.prefs.clearUserPref(DOM_CACHE);
@@ -57,9 +57,6 @@ registerCleanupFunction(() => {
  */
 function* openTab(url, options = {}) {
   let tab = yield addTab(url, options);
-  let content = tab.linkedBrowser.contentWindowAsCPOW;
-
-  gWindow = content.wrappedJSObject;
 
   // Setup the async storages in main window and for all its iframes
   yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
@@ -219,8 +216,6 @@ function forceCollections() {
  * Cleans up and finishes the test
  */
 function* finishTests() {
-  // Bug 1233497 makes it so that we can no longer yield CPOWs from Tasks.
-  // We work around this by calling clear() via a ContentTask instead.
   while (gBrowser.tabs.length > 1) {
     yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
       /**

From 3ca71a66e9a9f36340d0c1ea3b4c0c07bac8e075 Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Thu, 8 Mar 2018 15:32:06 +0000
Subject: [PATCH 18/50] Bug 1401129 - Restore
 datareporting.healthreport.about.reportUrl in automation tools. r=whimboo

The datareporting.healthreport.about.reportUrl preference was removed
in bug 1352497, but there are multiple automation tools in the tree
that target out-of-tree release channels.

This patch restores the preference with a note that it was removed
in Firefox 59.

MozReview-Commit-ID: Lg8bxoiIfxn

--HG--
extra : rebase_source : ce3744baf37b30210239a5b840ee9fb1f7dc38f4
---
 testing/geckodriver/src/prefs.rs                             | 3 ++-
 testing/marionette/client/marionette_driver/geckoinstance.py | 2 ++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/testing/geckodriver/src/prefs.rs b/testing/geckodriver/src/prefs.rs
index 407ed500a12e..6ce776567438 100644
--- a/testing/geckodriver/src/prefs.rs
+++ b/testing/geckodriver/src/prefs.rs
@@ -1,7 +1,7 @@
 use mozprofile::preferences::Pref;
 
 lazy_static! {
-    pub static ref DEFAULT: [(&'static str, Pref); 78] = [
+    pub static ref DEFAULT: [(&'static str, Pref); 79] = [
         // Disable automatic downloading of new releases
         ("app.update.auto", Pref::new(false)),
 
@@ -110,6 +110,7 @@ lazy_static! {
 
         // Do not show datareporting policy notifications which can
         // interfere with tests
+        ("datareporting.healthreport.about.reportUrl", Pref::new("http://%(server)s/dummy/abouthealthreport/")),  // removed in Firefox 59
         ("datareporting.healthreport.documentServerURI", Pref::new("http://%(server)s/dummy/healthreport/")),
         ("datareporting.healthreport.logging.consoleEnabled", Pref::new(false)),
         ("datareporting.healthreport.service.enabled", Pref::new(false)),
diff --git a/testing/marionette/client/marionette_driver/geckoinstance.py b/testing/marionette/client/marionette_driver/geckoinstance.py
index fe7524b7e19b..4e5f2947099c 100644
--- a/testing/marionette/client/marionette_driver/geckoinstance.py
+++ b/testing/marionette/client/marionette_driver/geckoinstance.py
@@ -33,6 +33,8 @@ class GeckoInstance(object):
         "apz.content_response_timeout": 60000,
 
         # Do not send Firefox health reports to the production server
+        # removed in Firefox 59
+        "datareporting.healthreport.about.reportUrl": "http://%(server)s/dummy/abouthealthreport/",
         "datareporting.healthreport.documentServerURI": "http://%(server)s/dummy/healthreport/",
 
         # Do not show datareporting policy notifications which can interfer with tests

From 77efd9020a7737e330d074b8065a7844215d4e54 Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Thu, 8 Mar 2018 15:47:09 +0000
Subject: [PATCH 19/50] Bug 1401129 - Restore
 extensions.shield-recipe-client.api_url in automation tools. r=whimboo

The extensions.shield-recipe-client.api_url preference was
replaced with app.normandy.api_url in bug 1436113.  There are
multiple automation tools in the tree that target out-of-tree
release channels and removing the old preference would break these.

This patch re-adds the old preference with a note of when it was removed.

MozReview-Commit-ID: HhTfRFkRQTC

--HG--
extra : rebase_source : ec726c528b57e197a34e3e094c1c4bfe5d23da55
---
 testing/geckodriver/src/prefs.rs                     |  8 ++++++--
 .../client/marionette_driver/geckoinstance.py        |  6 +++++-
 testing/marionette/components/marionette.js          |  6 +++---
 .../marionette_harness/tests/unit/test_prefs.py      | 12 ++++++++++--
 4 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/testing/geckodriver/src/prefs.rs b/testing/geckodriver/src/prefs.rs
index 6ce776567438..d1d3d64043d9 100644
--- a/testing/geckodriver/src/prefs.rs
+++ b/testing/geckodriver/src/prefs.rs
@@ -1,7 +1,10 @@
 use mozprofile::preferences::Pref;
 
 lazy_static! {
-    pub static ref DEFAULT: [(&'static str, Pref); 79] = [
+    pub static ref DEFAULT: [(&'static str, Pref); 80] = [
+        // Make sure Shield doesn't hit the network.
+        ("app.normandy.api_url", Pref::new("")),
+
         // Disable automatic downloading of new releases
         ("app.update.auto", Pref::new(false)),
 
@@ -145,7 +148,8 @@ lazy_static! {
         ("extensions.installDistroAddons", Pref::new(false)),
 
         // Make sure Shield doesn't hit the network.
-        ("app.normandy.api_url", Pref::new("")),
+        // Removed in Firefox 60.
+        ("extensions.shield-recipe-client.api_url", Pref::new("")),
 
         ("extensions.showMismatchUI", Pref::new(false)),
 
diff --git a/testing/marionette/client/marionette_driver/geckoinstance.py b/testing/marionette/client/marionette_driver/geckoinstance.py
index 4e5f2947099c..fa3ea8247db3 100644
--- a/testing/marionette/client/marionette_driver/geckoinstance.py
+++ b/testing/marionette/client/marionette_driver/geckoinstance.py
@@ -24,6 +24,9 @@ from . import errors
 
 class GeckoInstance(object):
     required_prefs = {
+        # Make sure Shield doesn't hit the network.
+        "app.normandy.api_url": "",
+
         # Increase the APZ content response timeout in tests to 1 minute.
         # This is to accommodate the fact that test environments tends to be slower
         # than production environments (with the b2g emulator being the slowest of them
@@ -55,7 +58,8 @@ class GeckoInstance(object):
         # Disable intalling any distribution add-ons
         "extensions.installDistroAddons": False,
         # Make sure Shield doesn't hit the network.
-        "app.normandy.api_url": "",
+        # Removed in Firefox 60.
+        "extensions.shield-recipe-client.api_url": "",
         "extensions.showMismatchUI": False,
         # Turn off extension updates so they don't bother tests
         "extensions.update.enabled": False,
diff --git a/testing/marionette/components/marionette.js b/testing/marionette/components/marionette.js
index 65b031c8556b..d89c3adb150c 100644
--- a/testing/marionette/components/marionette.js
+++ b/testing/marionette/components/marionette.js
@@ -54,6 +54,9 @@ const ENV_PRESERVE_PREFS = "MOZ_MARIONETTE_PREF_STATE_ACROSS_RESTARTS";
 // are checked before Marionette initialises.
 const RECOMMENDED_PREFS = new Map([
 
+  // Make sure Shield doesn't hit the network.
+  ["app.normandy.api_url", ""],
+
   // Disable automatic downloading of new releases.
   //
   // This should also be set in the profile prior to starting Firefox,
@@ -197,9 +200,6 @@ const RECOMMENDED_PREFS = new Map([
   // Should be set in profile.
   ["extensions.installDistroAddons", false],
 
-  // Make sure Shield doesn't hit the network.
-  ["extensions.shield-recipe-client.api_url", ""],
-
   ["extensions.showMismatchUI", false],
 
   // Turn off extension updates so they do not bother tests
diff --git a/testing/marionette/harness/marionette_harness/tests/unit/test_prefs.py b/testing/marionette/harness/marionette_harness/tests/unit/test_prefs.py
index 48f392450d62..2f12572d3e6a 100644
--- a/testing/marionette/harness/marionette_harness/tests/unit/test_prefs.py
+++ b/testing/marionette/harness/marionette_harness/tests/unit/test_prefs.py
@@ -32,8 +32,16 @@ class TestPreferences(MarionetteTestCase):
         required_prefs = geckoinstance.GeckoInstance.required_prefs
 
         for key, value in required_prefs.iteritems():
-            self.assertEqual(self.marionette.get_pref(key), value,
-                             "Preference {} hasn't been set to {}".format(key, value))
+            # The extensions.shield-recipe-client.* prefs branch
+            # is as of Firefox 60 migrated to app.normandy.*.
+            #
+            # This is a workaround that can be removed together
+            # with extensions.shield-recipe-client.api_url.
+            if key == "extensions.shield-recipe-client.api_url":
+                self.assertEqual(self.marionette.get_pref("app.normandy.api_url"), value)
+            else:
+                self.assertEqual(self.marionette.get_pref(key), value,
+                                 "Preference {} hasn't been set to {}".format(key, repr(value)))
 
     @skip_if_mobile("Only runnable with Firefox")
     def test_desktop_instance_preferences(self):

From 33d987d48ad47a4013e6964d3279dfdd04670db4 Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Mon, 12 Mar 2018 11:47:28 +0000
Subject: [PATCH 20/50] Bug 1401129 - Add peer review note to automation files.
 r=whimboo

MozReview-Commit-ID: 47708JTKoro

--HG--
extra : rebase_source : 234d2b84008937a6df8a36dcf05d341a0c4ae387
---
 testing/geckodriver/src/prefs.rs                          | 7 +++++++
 .../marionette/client/marionette_driver/geckoinstance.py  | 8 ++++++++
 2 files changed, 15 insertions(+)

diff --git a/testing/geckodriver/src/prefs.rs b/testing/geckodriver/src/prefs.rs
index d1d3d64043d9..d2dd0c2d36c8 100644
--- a/testing/geckodriver/src/prefs.rs
+++ b/testing/geckodriver/src/prefs.rs
@@ -1,5 +1,12 @@
 use mozprofile::preferences::Pref;
 
+// ALL CHANGES TO THIS FILE MUST HAVE REVIEW FROM A GECKODRIVER PEER!
+//
+// The Marionette Python client is used out-of-tree with release
+// channel builds of Firefox.  Removing a preference from this file
+// will cause regressions, so please be careful and get review from
+// a Testing :: Marionette peer before you make any changes to this file.
+
 lazy_static! {
     pub static ref DEFAULT: [(&'static str, Pref); 80] = [
         // Make sure Shield doesn't hit the network.
diff --git a/testing/marionette/client/marionette_driver/geckoinstance.py b/testing/marionette/client/marionette_driver/geckoinstance.py
index fa3ea8247db3..7c3780e8c570 100644
--- a/testing/marionette/client/marionette_driver/geckoinstance.py
+++ b/testing/marionette/client/marionette_driver/geckoinstance.py
@@ -22,6 +22,14 @@ from six import reraise
 from . import errors
 
 
+# ALL CHANGES TO THIS FILE MUST HAVE REVIEW FROM A MARIONETTE PEER!
+#
+# The Marionette Python client is used out-of-tree with release
+# channel builds of Firefox.  Removing a preference from this file
+# will cause regressions, so please be careful and get review from
+# a Testing :: Marionette peer before you make any changes to this file.
+
+
 class GeckoInstance(object):
     required_prefs = {
         # Make sure Shield doesn't hit the network.

From 7b875989b286162b43df83938318f81ddd033b3b Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Mon, 12 Mar 2018 11:48:18 +0000
Subject: [PATCH 21/50] Bug 1401129 - Release mozversion 0.1.3. r=whimboo

MozReview-Commit-ID: JMUOjttq31L

--HG--
extra : rebase_source : 188ea63b2a3aff99562df94bb7c4a9e164cfea54
---
 Cargo.lock                                 | 4 ++--
 testing/mozbase/rust/mozversion/Cargo.toml | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 4bfba0eb2f52..c0d81e99414f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -674,7 +674,7 @@ dependencies = [
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozprofile 0.3.0",
  "mozrunner 0.5.0",
- "mozversion 0.1.2",
+ "mozversion 0.1.3",
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "uuid 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1093,7 +1093,7 @@ dependencies = [
 
 [[package]]
 name = "mozversion"
-version = "0.1.2"
+version = "0.1.3"
 dependencies = [
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rust-ini 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/testing/mozbase/rust/mozversion/Cargo.toml b/testing/mozbase/rust/mozversion/Cargo.toml
index 30daf0d0d82b..78308ae3d5db 100644
--- a/testing/mozbase/rust/mozversion/Cargo.toml
+++ b/testing/mozbase/rust/mozversion/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "mozversion"
-version = "0.1.2"
+version = "0.1.3"
 authors = ["James Graham <james@hoppipolla.co.uk>"]
 description = "Utility for accessing Firefox version metadata"
 keywords = ["mozilla", "firefox"]

From 6b09cf8df1874b5e5e3cb29dc4625d2c23e29d63 Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Thu, 8 Mar 2018 14:26:10 +0000
Subject: [PATCH 22/50] Bug 1401129 - Release mozrunner 0.6.0. r=whimboo

MozReview-Commit-ID: 2nljPi3HN5b

--HG--
extra : rebase_source : 7e1cd2201937b5bb47fe81bcdbd6c1bc068b92b5
---
 Cargo.lock                                | 4 ++--
 testing/mozbase/rust/mozrunner/Cargo.toml | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c0d81e99414f..c17a4386cd50 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -673,7 +673,7 @@ dependencies = [
  "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozprofile 0.3.0",
- "mozrunner 0.5.0",
+ "mozrunner 0.6.0",
  "mozversion 0.1.3",
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1084,7 +1084,7 @@ dependencies = [
 
 [[package]]
 name = "mozrunner"
-version = "0.5.0"
+version = "0.6.0"
 dependencies = [
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozprofile 0.3.0",
diff --git a/testing/mozbase/rust/mozrunner/Cargo.toml b/testing/mozbase/rust/mozrunner/Cargo.toml
index 41e3fb0b28ce..54a5a0469d59 100644
--- a/testing/mozbase/rust/mozrunner/Cargo.toml
+++ b/testing/mozbase/rust/mozrunner/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "mozrunner"
-version = "0.5.0"
-authors = ["Mozilla Tools and Automation <auto-tools@mozilla.com>"]
+version = "0.6.0"
+authors = ["Mozilla"]
 description = "Library for starting Firefox binaries."
 repository = "https://hg.mozilla.org/mozilla-central/file/tip/testing/mozbase/rust/mozrunner"
 license = "MPL-2.0"

From 4dcf6c50b71b9ad0d67db894e6bb600138a120b6 Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Thu, 8 Mar 2018 16:05:08 +0000
Subject: [PATCH 23/50] Bug 1401129 - Release webdriver 0.35.0. r=whimboo

MozReview-Commit-ID: lnoyZZbtcF

--HG--
extra : rebase_source : c43d960f793cd3d3eed922ac8ebe31d9a0564d12
---
 Cargo.lock                   | 4 ++--
 testing/webdriver/Cargo.toml | 6 +++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index c17a4386cd50..f749c08b7109 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -678,7 +678,7 @@ dependencies = [
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "rustc-serialize 0.3.24 (registry+https://github.com/rust-lang/crates.io-index)",
  "uuid 0.1.18 (registry+https://github.com/rust-lang/crates.io-index)",
- "webdriver 0.34.0",
+ "webdriver 0.35.0",
  "zip 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1992,7 +1992,7 @@ dependencies = [
 
 [[package]]
 name = "webdriver"
-version = "0.34.0"
+version = "0.35.0"
 dependencies = [
  "cookie 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "hyper 0.10.13 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/testing/webdriver/Cargo.toml b/testing/webdriver/Cargo.toml
index 97b4f86443fe..aa83640a8227 100644
--- a/testing/webdriver/Cargo.toml
+++ b/testing/webdriver/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "webdriver"
-version = "0.34.0"
-authors = ["Mozilla <tools-marionette@lists.mozilla.org>"]
+version = "0.35.0"
+authors = ["Mozilla"]
 description = "Library implementing the wire protocol for the W3C WebDriver specification."
 keywords = ["webdriver", "browser", "automation", "protocol", "w3c"]
 documentation = "https://docs.rs/webdriver"
@@ -16,5 +16,5 @@ log = "0.4"
 regex = "0.2"
 rustc-serialize = "0.3"
 time = "0.1"
+unicode-segmentation = "1.1.0"
 url = "1"
-unicode-segmentation = "1.1.0"
\ No newline at end of file

From 2dad6ae4c672fc1c8fb88452a619e355ed84ff22 Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Thu, 8 Mar 2018 16:05:35 +0000
Subject: [PATCH 24/50] Bug 1401129 - Note changes for geckodriver 0.20.0
 release. r=whimboo

MozReview-Commit-ID: 1vb4nzpUlYD

--HG--
extra : rebase_source : df910b9829a9a4cc1d8c5de5196b2c93fad61581
---
 testing/geckodriver/CHANGES.md | 43 ++++++++++++++++++++++++----------
 1 file changed, 31 insertions(+), 12 deletions(-)

diff --git a/testing/geckodriver/CHANGES.md b/testing/geckodriver/CHANGES.md
index 336eb5cba5f9..9f9dedc94382 100644
--- a/testing/geckodriver/CHANGES.md
+++ b/testing/geckodriver/CHANGES.md
@@ -3,12 +3,12 @@ Change log
 
 All notable changes to this program is documented in this file.
 
-Unreleased
-----------
+0.20.0 (2018-03-08)
+-------------------
 
 ### Added
 
-- New `--jsdebugger` flag to open the Browser Toolbox when Firefox
+- New `--jsdebugger` flag to open the [Browser Toolbox] when Firefox
   launches.  This is useful for debugging Marionette internals.
 
 - Introduced the temporary, boolean capability
@@ -18,19 +18,35 @@ Unreleased
 ### Changed
 
 - HTTP status code for the [`StaleElementReference`] error changed
-  from 400 (Bad Request) to 404 (Not Found)
+  from 400 (Bad Request) to 404 (Not Found).
 
 - Backtraces from geckodriver no longer substitute for missing
-  Marionette stacktraces
+  Marionette stacktraces.
 
-- `Delete Session` now allows Firefox to safely shutdown within 70s before
-  force-killing the process
-
-- Changed preference used to disable shield studies to `app.normandy.api_url`.
+- [webdriver crate] upgraded to 0.35.0.
 
 ### Fixed
 
-- Improved error messages for malformed capabilities
+- The Firefox process is now given ample time to shut down, allowing
+  enough time for the Firefox shutdown hang monitor to kick in.
+
+  Firefox has an integrated background monitor that observes
+  long-running threads during shutdown.  These threads will be
+  killed after 63 seconds in the event of a hang.  To allow Firefox
+  to shut down these threads on its own, geckodriver has to wait
+  that time and some additional seconds.
+
+- Grapheme clusters are now accepted as input for keyboard input
+  to actions.
+
+  Input to the `value` field of the `keyDown` and `keyUp` action
+  primitives used to only accept single characters, which means
+  geckodriver would error when a valid grapheme cluster was sent in,
+  for example with the tamil nadu character U+0BA8 U+0BBF.
+
+  Thanks to Greg Fraley for fixing this bug.
+
+- Improved error messages for malformed capability values.
 
 
 0.19.1 (2017-10-30)
@@ -793,9 +809,11 @@ and greater.
 
 
 [README]: https://github.com/mozilla/geckodriver/blob/master/README.md
+[Browser Toolbox]: https://developer.mozilla.org/en-US/docs/Tools/Browser_Toolbox
 
 [`CloseWindowResponse`]: https://docs.rs/webdriver/newest/webdriver/response/struct.CloseWindowResponse.html
 [`CookieResponse`]: https://docs.rs/webdriver/newest/webdriver/response/struct.CookieResponse.html
+[`DeleteSession`]: https://docs.rs/webdriver/newest/webdriver/command/enum.WebDriverCommand.html#variant.DeleteSession
 [`ElementClickIntercepted`]: https://docs.rs/webdriver/newest/webdriver/error/enum.ErrorStatus.html#variant.ElementClickIntercepted
 [`ElementNotInteractable`]: https://docs.rs/webdriver/newest/webdriver/error/enum.ErrorStatus.html#variant.ElementNotInteractable
 [`FullscreenWindow`]: https://docs.rs/webdriver/newest/webdriver/command/enum.WebDriverCommand.html#variant.FullscreenWindow
@@ -821,15 +839,16 @@ and greater.
 [webdriver crate]: https://crates.io/crates/webdriver
 
 [Actions]: https://w3c.github.io/webdriver/webdriver-spec.html#actions
+[Delete Session]: https://w3c.github.io/webdriver/webdriver-spec.html#delete-session
 [Element Click]: https://w3c.github.io/webdriver/webdriver-spec.html#element-click
 [Get Timeouts]: https://w3c.github.io/webdriver/webdriver-spec.html#get-timeouts
-[Set Timeouts]: https://w3c.github.io/webdriver/webdriver-spec.html#set-timeouts
 [Get Window Rect]: https://w3c.github.io/webdriver/webdriver-spec.html#get-window-rect
-[Set Window Rect]: https://w3c.github.io/webdriver/webdriver-spec.html#set-window-rect
 [insecure certificate]: https://w3c.github.io/webdriver/webdriver-spec.html#dfn-insecure-certificate
 [Minimize Window]: https://w3c.github.io/webdriver/webdriver-spec.html#minimize-window
 [New Session]: https://w3c.github.io/webdriver/webdriver-spec.html#new-session
 [Send Alert Text]: https://w3c.github.io/webdriver/webdriver-spec.html#send-alert-text
+[Set Timeouts]: https://w3c.github.io/webdriver/webdriver-spec.html#set-timeouts
+[Set Window Rect]: https://w3c.github.io/webdriver/webdriver-spec.html#set-window-rect
 [Status]: https://w3c.github.io/webdriver/webdriver-spec.html#status
 [Take Element Screenshot]: https://w3c.github.io/webdriver/webdriver-spec.html#take-element-screenshot
 [WebDriver errors]: https://w3c.github.io/webdriver/webdriver-spec.html#handling-errors

From ea34c24a48f5a3a56b969f1b261710f70e72306d Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Thu, 8 Mar 2018 16:06:59 +0000
Subject: [PATCH 25/50] Bug 1401129 - Release geckodriver 0.20.0. r=whimboo

MozReview-Commit-ID: Lip1pab8D0f

--HG--
extra : rebase_source : 89fd332817e87cd0d7e45ed527d714237131e842
---
 Cargo.lock                     | 2 +-
 testing/geckodriver/Cargo.toml | 3 +--
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index f749c08b7109..d437e04e3cf3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -665,7 +665,7 @@ dependencies = [
 
 [[package]]
 name = "geckodriver"
-version = "0.19.1"
+version = "0.20.0"
 dependencies = [
  "chrono 0.2.25 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.29.0 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/testing/geckodriver/Cargo.toml b/testing/geckodriver/Cargo.toml
index 3d5a7063decf..3c70d6e7a093 100644
--- a/testing/geckodriver/Cargo.toml
+++ b/testing/geckodriver/Cargo.toml
@@ -1,7 +1,6 @@
 [package]
 name = "geckodriver"
-version = "0.19.1"
-authors = ["Mozilla <tools-marionette@lists.mozilla.org>"]
+version = "0.20.0"
 description = "Proxy for using WebDriver clients to interact with Gecko-based browsers."
 keywords = ["webdriver", "w3c", "httpd", "mozilla", "firefox"]
 repository = "https://hg.mozilla.org/mozilla-central/file/tip/testing/geckodriver"

From 547748db6bba1d082d644f72c50b1d407df0d175 Mon Sep 17 00:00:00 2001
From: Xidorn Quan <me@upsuper.org>
Date: Tue, 6 Mar 2018 17:47:15 +1100
Subject: [PATCH 26/50] Bug 1443392 - Send resize event when FRAMECHANGED flag
 is set even if the window isn't resized. r=jimm

MozReview-Commit-ID: 9wpiFr9Tw9c

--HG--
extra : rebase_source : e1f97df2afd9c76fba87684752662a78e9b851c9
---
 widget/windows/nsWindow.cpp | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/widget/windows/nsWindow.cpp b/widget/windows/nsWindow.cpp
index 52495d722136..c9baa8260cc7 100644
--- a/widget/windows/nsWindow.cpp
+++ b/widget/windows/nsWindow.cpp
@@ -6790,11 +6790,24 @@ void nsWindow::OnWindowPosChanged(WINDOWPOS* wp)
         return;
       }
     }
+  }
 
-    // Recalculate the width and height based on the client area for gecko events.
-    LayoutDeviceIntSize clientSize(newWidth, newHeight);
+  // Notify the widget listener for size change of client area for gecko
+  // events. This needs to be done when either window size is changed,
+  // or window frame is changed. They may not happen together.
+  // However, we don't invoke that for popup when window frame changes,
+  // because popups may trigger frame change before size change via
+  // {Set,Clear}ThemeRegion they invoke in Resize. That would make the
+  // code below call OnResize with a wrong client size first, which can
+  // lead to flickerling for some popups.
+  if (!(wp->flags & SWP_NOSIZE) ||
+      ((wp->flags & SWP_FRAMECHANGED) && !IsPopup())) {
+    RECT r;
+    LayoutDeviceIntSize clientSize;
     if (::GetClientRect(mWnd, &r)) {
       clientSize = WinUtils::ToIntRect(r).Size();
+    } else {
+      clientSize = mBounds.Size();
     }
     // Send a gecko resize event
     OnResize(clientSize);

From 34114150a6b99f8afd1815d6e345ba4f3efeaa15 Mon Sep 17 00:00:00 2001
From: Mike Conley <mconley@mozilla.com>
Date: Wed, 31 Jan 2018 12:10:03 -0500
Subject: [PATCH 27/50] Bug 1423220 - Enable tab warming by default for Nightly
 builds. r=dao

MozReview-Commit-ID: 8bz1U1WSzy5

--HG--
extra : rebase_source : f74a9b240c234d329f0e8d27ef6c4a84a4cc6de7
---
 browser/app/profile/firefox.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index 7e4816503435..4adfff98f013 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -1541,8 +1541,12 @@ pref("browser.tabs.remote.desktopbehavior", true);
 
 // For speculatively warming up tabs to improve perceived
 // performance while using the async tab switcher.
-// Disabled until bug 1397426 is fixed.
+#if defined(NIGHTLY_BUILD)
+pref("browser.tabs.remote.warmup.enabled", true);
+#else
 pref("browser.tabs.remote.warmup.enabled", false);
+#endif
+
 pref("browser.tabs.remote.warmup.maxTabs", 3);
 pref("browser.tabs.remote.warmup.unloadDelayMs", 2000);
 

From af806c4bab88a8d5f2056227aa5cb4c5f589b26c Mon Sep 17 00:00:00 2001
From: Andreas Tolfsen <ato@sny.no>
Date: Sun, 11 Mar 2018 15:51:00 +0000
Subject: [PATCH 28/50] Bug 1444431 - Filter logs from familiar logging
 targets. r=jgraham

geckodriver uses log 0.4, but it depends on a version of hyper that
uses log 0.3.

Previously this meant that geckodriver's logger could only see
messages from crates using log 0.4, and had no access to messages
from hyper or other crates using log 0.3.  However, log 0.3.9 added
interoperability so that programs built with a mix of log 0.3 and
log 0.4 can again display messages from all crates.

This patches geckodriver::logging to contain a whitelist of logged
targets we care about.  Currently this list includes geckodriver,
mozprofile, mozrunner, mozversion, and webdriver.  This will revert
us to the behaviour prior to upgrading hyper to use log 0.3.9,
and would be similar to the old implementation we had for filtering
logs we had when geckodriver used slog.

Thanks-to: Matt Brubeck <mbrubeck@mozilla.com>
MozReview-Commit-ID: 6Xj0k6VD1dQ

--HG--
extra : rebase_source : 7a5aee1642b94516eedc1ca25b722e2868d0983b
---
 testing/geckodriver/src/logging.rs | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/testing/geckodriver/src/logging.rs b/testing/geckodriver/src/logging.rs
index f322994fe714..d9efd9ff7fc9 100644
--- a/testing/geckodriver/src/logging.rs
+++ b/testing/geckodriver/src/logging.rs
@@ -33,15 +33,20 @@ use std::fmt;
 use std::io;
 use std::io::Write;
 use std::str;
-use std::sync::atomic::{ATOMIC_USIZE_INIT, AtomicUsize, Ordering};
+use std::sync::atomic::{AtomicUsize, Ordering, ATOMIC_USIZE_INIT};
 
 static MAX_LOG_LEVEL: AtomicUsize = ATOMIC_USIZE_INIT;
+const LOGGED_TARGETS: &'static [&'static str] = &[
+    "geckodriver",
+    "mozprofile",
+    "mozrunner",
+    "mozversion",
+    "webdriver",
+];
 
 /// Logger levels from [Log.jsm].
 ///
-/// [Log.jsm]:
-/// https://developer.mozilla.org/en/docs/Mozilla/JavaScript_code_modules/Log.
-/// jsm
+/// [Log.jsm]: https://developer.mozilla.org/en/docs/Mozilla/JavaScript_code_modules/Log.jsm
 #[repr(usize)]
 #[derive(Clone, Copy, Eq, Debug, Hash, PartialEq)]
 pub enum Level {
@@ -134,7 +139,8 @@ struct Logger;
 
 impl log::Log for Logger {
     fn enabled(&self, meta: &log::Metadata) -> bool {
-        meta.level() <= log::max_level()
+        LOGGED_TARGETS.iter().any(|&x| meta.target().starts_with(x))
+            && meta.level() <= log::max_level()
     }
 
     fn log(&self, record: &log::Record) {

From c1c35dee0dd9a1e778b55d81ab15d7397e3df810 Mon Sep 17 00:00:00 2001
From: Masayuki Nakano <masayuki@d-toybox.com>
Date: Wed, 1 Mar 2017 15:41:43 +0900
Subject: [PATCH 29/50] Bug 1343451 - part 1: Declare (DOM|NS)_VK_PROCESSKEY
 for keyCode value during composition r=smaug

When native key event is handled by IME, we should set keyCode to 0xE5 (229,
VK_PROCESS of virtual keycode of Windows) for behaving same as the other
browsers.

This patch declares it same as other keyCode values.

MozReview-Commit-ID: 666bB1qOEgv

--HG--
extra : rebase_source : 8edcc49aab537240fb696b010e642848a6d439d4
---
 dom/events/VirtualKeyCodeList.h | 3 +++
 dom/webidl/KeyEvent.webidl      | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/dom/events/VirtualKeyCodeList.h b/dom/events/VirtualKeyCodeList.h
index 40615947ef8f..6660182fe7cd 100644
--- a/dom/events/VirtualKeyCodeList.h
+++ b/dom/events/VirtualKeyCodeList.h
@@ -212,6 +212,9 @@ DEFINE_VK_INTERNAL(_ALTGR)
 
 DEFINE_VK_INTERNAL(_WIN_ICO_HELP)
 DEFINE_VK_INTERNAL(_WIN_ICO_00)
+
+DEFINE_VK_INTERNAL(_PROCESSKEY)
+
 DEFINE_VK_INTERNAL(_WIN_ICO_CLEAR)
 DEFINE_VK_INTERNAL(_WIN_OEM_RESET)
 DEFINE_VK_INTERNAL(_WIN_OEM_JUMP)
diff --git a/dom/webidl/KeyEvent.webidl b/dom/webidl/KeyEvent.webidl
index abb4b6a34285..6fd66afc21d9 100644
--- a/dom/webidl/KeyEvent.webidl
+++ b/dom/webidl/KeyEvent.webidl
@@ -195,6 +195,12 @@ interface KeyEvent
   // for compatibility with the other web browsers on Windows.
   const unsigned long DOM_VK_WIN_ICO_HELP    = 0xE3;
   const unsigned long DOM_VK_WIN_ICO_00      = 0xE4;
+
+  // IME processed key.
+  const unsigned long DOM_VK_PROCESSKEY      = 0xE5;
+
+  // OEM specific virtual keyCode of Windows should pass through DOM keyCode
+  // for compatibility with the other web browsers on Windows.
   const unsigned long DOM_VK_WIN_ICO_CLEAR   = 0xE6;
   const unsigned long DOM_VK_WIN_OEM_RESET   = 0xE9;
   const unsigned long DOM_VK_WIN_OEM_JUMP    = 0xEA;

From 2b972e10f7ae7a032cb385ef2daa8566f8a7afe2 Mon Sep 17 00:00:00 2001
From: Masayuki Nakano <masayuki@d-toybox.com>
Date: Wed, 1 Mar 2017 15:58:50 +0900
Subject: [PATCH 30/50] Bug 1343451 - part 2: KeyboardLayout and NativeKey
 should use native key code value to check if the key event was handled by IME
 r=m_kato

On Windows, VK_PROCESSKEY key message is sent if the key event is handled by
IME (in IMM mode or IMM-IME).  Therefore, we can set
WidgetKeyboardEvent::mKeyCode to NS_VK_PROCESSKEY and
WidgetKeyboardEvent::mKeyNameIndex to KEY_NAME_INDEX_Process simply when
we receive VK_PROCESSKEY.

MozReview-Commit-ID: 9B8Q7rwfXYD

--HG--
extra : rebase_source : a15105e3b6acf1f1911a8299911353dc4179e2c0
---
 widget/NativeKeyToDOMKeyName.h    | 3 +++
 widget/tests/test_keycodes.xul    | 4 ++--
 widget/windows/KeyboardLayout.cpp | 2 +-
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/widget/NativeKeyToDOMKeyName.h b/widget/NativeKeyToDOMKeyName.h
index db0d73da69aa..bfd5baa948b3 100644
--- a/widget/NativeKeyToDOMKeyName.h
+++ b/widget/NativeKeyToDOMKeyName.h
@@ -529,6 +529,9 @@ KEY_MAP_ANDROID (NonConvert, AKEYCODE_MUHENKAN)
 // PreviousCandidate
 KEY_MAP_GTK     (PreviousCandidate, GDK_PreviousCandidate) // OADG 109, Mae Koho
 
+// Process
+KEY_MAP_WIN     (Process, VK_PROCESSKEY)
+
 // SingleCandidate
 KEY_MAP_GTK     (SingleCandidate, GDK_SingleCandidate)
 
diff --git a/widget/tests/test_keycodes.xul b/widget/tests/test_keycodes.xul
index 7ac53d57e17c..694c8ef476ed 100644
--- a/widget/tests/test_keycodes.xul
+++ b/widget/tests/test_keycodes.xul
@@ -3023,10 +3023,10 @@ function* runKeyEventTests()
     const WIN_VK_PROCESSKEY_WITH_SC_A = WIN_VK_PROCESSKEY | 0x001E0000;
     yield testKey({layout:KEYBOARD_LAYOUT_EN_US, keyCode:WIN_VK_PROCESSKEY_WITH_SC_A,
                    modifiers:{}, chars:"a"},
-                  ["a", "a", "Unidentified" /* TODO: Process */], "KeyA", 0 /* TODO: 0xE5 */, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
+                  ["a", "a", "Process"], "KeyA", KeyboardEvent.DOM_VK_PROCESSKEY, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
     yield testKey({layout:KEYBOARD_LAYOUT_EN_US, keyCode:WIN_VK_PROCESSKEY_WITH_SC_A,
                    modifiers:{altKey:1}, chars:"a"},
-                  ["a", "a", "Unidentified" /* TODO: Process */], "KeyA", 0 /* TODO: 0xE5 */, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
+                  ["a", "a", "Process"], "KeyA", KeyboardEvent.DOM_VK_PROCESSKEY, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
 
     // US
     // Alphabet
diff --git a/widget/windows/KeyboardLayout.cpp b/widget/windows/KeyboardLayout.cpp
index 947e914e4bef..2f7c43695f44 100644
--- a/widget/windows/KeyboardLayout.cpp
+++ b/widget/windows/KeyboardLayout.cpp
@@ -4805,7 +4805,7 @@ KeyboardLayout::ConvertNativeKeyCodeToDOMKeyCode(UINT aNativeKeyCode) const
 
     // VK_PROCESSKEY means IME already consumed the key event.
     case VK_PROCESSKEY:
-      return 0;
+      return NS_VK_PROCESSKEY;
     // VK_PACKET is generated by SendInput() API, we don't need to
     // care this message as key event.
     case VK_PACKET:

From 099a9bedeea736c4b6450bdffff0483c51089fd9 Mon Sep 17 00:00:00 2001
From: Masayuki Nakano <masayuki@d-toybox.com>
Date: Thu, 22 Feb 2018 19:52:53 +0900
Subject: [PATCH 31/50] Bug 1343451 - part 3-1: Make
 KeymapWrapper::InitKeyEvent() mark given key event as "processed by IME" if
 it has been handled by IME r=m_kato

For conforming UI Events spec, KeymapWrapper::InitKeyEvent() should initialize
mKeyCode and mKeyNameIndex with NS_VK_PROCESSKEY and KEY_NAME_INDEX_Process if
given keyboard event has already been handled by IME.

For making it know if given keyboard event has been handled by IME, this patch
adds additional bool argument to it and its callers.

Note that this patch changes keyCode value and key value of "keydown" event if
it's fired before "compositionstart" since Chromium does so on Linux.

MozReview-Commit-ID: FC3tfyeeopU

--HG--
extra : rebase_source : 9c88967b8e2a5539023deb1277ae8704418dfd0d
---
 widget/gtk/IMContextWrapper.cpp |  6 +++--
 widget/gtk/nsGtkKeyUtils.cpp    | 16 +++++++++-----
 widget/gtk/nsGtkKeyUtils.h      |  4 +++-
 widget/gtk/nsWindow.cpp         | 39 +++++++++++++++------------------
 widget/gtk/nsWindow.h           | 18 +++++++++++----
 5 files changed, 50 insertions(+), 33 deletions(-)

diff --git a/widget/gtk/IMContextWrapper.cpp b/widget/gtk/IMContextWrapper.cpp
index 33552fbe2c21..bb268da75dc2 100644
--- a/widget/gtk/IMContextWrapper.cpp
+++ b/widget/gtk/IMContextWrapper.cpp
@@ -1412,9 +1412,11 @@ IMContextWrapper::DispatchCompositionStart(GtkIMContext* aContext)
 
         // If this composition is started by a native keydown event, we need to
         // dispatch our keydown event here (before composition start).
+        // Note that make the preceding eKeyDown event marked as "processed
+        // by IME" for compatibility with Chromium.
         bool isCancelled;
-        mLastFocusedWindow->DispatchKeyDownEvent(mProcessingKeyEvent,
-                                                 &isCancelled);
+        mLastFocusedWindow->DispatchKeyDownOrKeyUpEvent(mProcessingKeyEvent,
+                                                        true, &isCancelled);
         MOZ_LOG(gGtkIMLog, LogLevel::Debug,
             ("0x%p   DispatchCompositionStart(), preceding keydown event is "
              "dispatched",
diff --git a/widget/gtk/nsGtkKeyUtils.cpp b/widget/gtk/nsGtkKeyUtils.cpp
index a336c1ad6c92..6a02b9a1bc67 100644
--- a/widget/gtk/nsGtkKeyUtils.cpp
+++ b/widget/gtk/nsGtkKeyUtils.cpp
@@ -931,14 +931,19 @@ KeymapWrapper::ComputeDOMCodeNameIndex(const GdkEventKey* aGdkKeyEvent)
 
 /* static */ void
 KeymapWrapper::InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
-                            GdkEventKey* aGdkKeyEvent)
+                            GdkEventKey* aGdkKeyEvent,
+                            bool aIsProcessedByIME)
 {
+    MOZ_ASSERT(!aIsProcessedByIME || aKeyEvent.mMessage != eKeyPress,
+      "If the key event is handled by IME, keypress event shouldn't be fired");
+
     KeymapWrapper* keymapWrapper = GetInstance();
 
     aKeyEvent.mCodeNameIndex = ComputeDOMCodeNameIndex(aGdkKeyEvent);
     MOZ_ASSERT(aKeyEvent.mCodeNameIndex != CODE_NAME_INDEX_USE_STRING);
     aKeyEvent.mKeyNameIndex =
-        keymapWrapper->ComputeDOMKeyNameIndex(aGdkKeyEvent);
+        aIsProcessedByIME ? KEY_NAME_INDEX_Process :
+                            keymapWrapper->ComputeDOMKeyNameIndex(aGdkKeyEvent);
     if (aKeyEvent.mKeyNameIndex == KEY_NAME_INDEX_Unidentified) {
         uint32_t charCode = GetCharCodeFor(aGdkKeyEvent);
         if (!charCode) {
@@ -951,10 +956,11 @@ KeymapWrapper::InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
             AppendUCS4ToUTF16(charCode, aKeyEvent.mKeyValue);
         }
     }
-    aKeyEvent.mKeyCode = ComputeDOMKeyCode(aGdkKeyEvent);
 
-    if (aKeyEvent.mKeyNameIndex != KEY_NAME_INDEX_USE_STRING ||
-        aKeyEvent.mMessage != eKeyPress) {
+    if (aIsProcessedByIME) {
+        aKeyEvent.mKeyCode = NS_VK_PROCESSKEY;
+    } else if (aKeyEvent.mKeyNameIndex != KEY_NAME_INDEX_USE_STRING ||
+               aKeyEvent.mMessage != eKeyPress) {
         aKeyEvent.mKeyCode = ComputeDOMKeyCode(aGdkKeyEvent);
     } else {
         aKeyEvent.mKeyCode = 0;
diff --git a/widget/gtk/nsGtkKeyUtils.h b/widget/gtk/nsGtkKeyUtils.h
index 3dc8a4f6a936..a1b9e53f0daa 100644
--- a/widget/gtk/nsGtkKeyUtils.h
+++ b/widget/gtk/nsGtkKeyUtils.h
@@ -131,9 +131,11 @@ public:
      * @param aKeyEvent         It's an WidgetKeyboardEvent which needs to be
      *                          initialized.
      * @param aGdkKeyEvent      A native GDK key event.
+     * @param aIsProcessedByIME true if aGdkKeyEvent is handled by IME.
      */
     static void InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
-                             GdkEventKey* aGdkKeyEvent);
+                             GdkEventKey* aGdkKeyEvent,
+                             bool aIsProcessedByIME);
 
     /**
      * WillDispatchKeyboardEvent() is called via
diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index dcbff364916b..ae342a557b6b 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -2937,13 +2937,15 @@ IsCtrlAltTab(GdkEventKey *aEvent)
 }
 
 bool
-nsWindow::DispatchKeyDownEvent(GdkEventKey *aEvent, bool *aCancelled)
+nsWindow::DispatchKeyDownOrKeyUpEvent(GdkEventKey* aEvent,
+                                      bool aIsProcessedByIME,
+                                      bool* aIsCancelled)
 {
-    NS_PRECONDITION(aCancelled, "aCancelled must not be null");
+    MOZ_ASSERT(aIsCancelled, "aCancelled must not be null");
 
-    *aCancelled = false;
+    *aIsCancelled = false;
 
-    if (IsCtrlAltTab(aEvent)) {
+    if (aEvent->type == GDK_KEY_PRESS && IsCtrlAltTab(aEvent)) {
         return false;
     }
 
@@ -2953,13 +2955,14 @@ nsWindow::DispatchKeyDownEvent(GdkEventKey *aEvent, bool *aCancelled)
         return FALSE;
     }
 
-    WidgetKeyboardEvent keydownEvent(true, eKeyDown, this);
-    KeymapWrapper::InitKeyEvent(keydownEvent, aEvent);
+    EventMessage message =
+        aEvent->type == GDK_KEY_PRESS ? eKeyDown : eKeyUp;
+    WidgetKeyboardEvent keyEvent(true, message, this);
+    KeymapWrapper::InitKeyEvent(keyEvent, aEvent, aIsProcessedByIME);
     nsEventStatus status = nsEventStatus_eIgnore;
     bool dispatched =
-        dispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent,
-                                          status, aEvent);
-    *aCancelled = (status == nsEventStatus_eConsumeNoDefault);
+        dispatcher->DispatchKeyboardEvent(message, keyEvent, status, aEvent);
+    *aIsCancelled = (status == nsEventStatus_eConsumeNoDefault);
     return dispatched ? TRUE : FALSE;
 }
 
@@ -3045,7 +3048,7 @@ nsWindow::OnKeyPressEvent(GdkEventKey *aEvent)
     // KEYDOWN -> KEYPRESS -> KEYUP -> KEYDOWN -> KEYPRESS -> KEYUP...
 
     bool isKeyDownCancelled = false;
-    if (DispatchKeyDownEvent(aEvent, &isKeyDownCancelled) &&
+    if (DispatchKeyDownOrKeyUpEvent(aEvent, false, &isKeyDownCancelled) &&
         (MOZ_UNLIKELY(mIsDestroyed) || isKeyDownCancelled)) {
         return TRUE;
     }
@@ -3094,7 +3097,7 @@ nsWindow::OnKeyPressEvent(GdkEventKey *aEvent)
     }
 
     WidgetKeyboardEvent keypressEvent(true, eKeyPress, this);
-    KeymapWrapper::InitKeyEvent(keypressEvent, aEvent);
+    KeymapWrapper::InitKeyEvent(keypressEvent, aEvent, false);
 
     // before we dispatch a key, check if it's the context menu key.
     // If so, send a context menu key event instead.
@@ -3178,7 +3181,7 @@ nsWindow::MaybeDispatchContextMenuEvent(const GdkEventKey* aEvent)
 }
 
 gboolean
-nsWindow::OnKeyReleaseEvent(GdkEventKey *aEvent)
+nsWindow::OnKeyReleaseEvent(GdkEventKey* aEvent)
 {
     LOGFOCUS(("OnKeyReleaseEvent [%p]\n", (void *)this));
 
@@ -3186,17 +3189,11 @@ nsWindow::OnKeyReleaseEvent(GdkEventKey *aEvent)
         return TRUE;
     }
 
-    RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
-    nsresult rv = dispatcher->BeginNativeInputTransaction();
-    if (NS_WARN_IF(NS_FAILED(rv))) {
-        return false;
+    bool isCancelled = false;
+    if (NS_WARN_IF(!DispatchKeyDownOrKeyUpEvent(aEvent, false, &isCancelled))) {
+        return FALSE;
     }
 
-    WidgetKeyboardEvent keyupEvent(true, eKeyUp, this);
-    KeymapWrapper::InitKeyEvent(keyupEvent, aEvent);
-    nsEventStatus status = nsEventStatus_eIgnore;
-    dispatcher->DispatchKeyboardEvent(eKeyUp, keyupEvent, status, aEvent);
-
     return TRUE;
 }
 
diff --git a/widget/gtk/nsWindow.h b/widget/gtk/nsWindow.h
index 0d57c156f49f..e7ed6f47c044 100644
--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -278,10 +278,20 @@ public:
                                          guint aTime);
     static void        UpdateDragStatus (GdkDragContext *aDragContext,
                                          nsIDragService *aDragService);
-    // If this dispatched the keydown event actually, this returns TRUE,
-    // otherwise, FALSE.
-    bool               DispatchKeyDownEvent(GdkEventKey *aEvent,
-                                            bool *aIsCancelled);
+    /**
+     * DispatchKeyDownOrKeyUpEvent() dispatches eKeyDown or eKeyUp event.
+     *
+     * @param aEvent            A native GDK_KEY_PRESS or GDK_KEY_RELEASE
+     *                          event.
+     * @param aProcessedByIME   true if the event is handled by IME.
+     * @param aIsCancelled      [Out] true if the default is prevented.
+     * @return                  true if eKeyDown event is actually dispatched.
+     *                          Otherwise, false.
+     */
+    bool DispatchKeyDownOrKeyUpEvent(GdkEventKey* aEvent,
+                                     bool aProcessedByIME,
+                                     bool* aIsCancelled);
+
     WidgetEventTime    GetWidgetEventTime(guint32 aEventTime);
     mozilla::TimeStamp GetEventTimeStamp(guint32 aEventTime);
     mozilla::CurrentX11TimeGetter* GetCurrentTimeGetter();

From fd292edc43a4bb48567d47cc96d712777e9ae5cd Mon Sep 17 00:00:00 2001
From: Masayuki Nakano <masayuki@d-toybox.com>
Date: Thu, 22 Feb 2018 20:56:08 +0900
Subject: [PATCH 32/50] Bug 1343451 - part 3-2: Make IMContextWrapper dispatch
 eKeyDown event or eKeyUp event if IME handles native key event but we have
 not dispatched DOM event for it yet r=m_kato

Currently, IMContextWrapper doesn't dispatch eKeyDown event and eKeyUp event
if it's handled by IME.  However, for conforming to UI Events, it should
not eat given keyboard events completely.

This patch makes IMContextWrapper dispatches eKeyDown event or eKeyUp event
before dispatching first event of composition events or content command
event.

MozReview-Commit-ID: H2jHpViTH5Q

--HG--
extra : rebase_source : 4129620126a34e27af1503e7c4652bb09c7e9bb6
---
 widget/gtk/IMContextWrapper.cpp | 239 ++++++++++++++++++++------------
 widget/gtk/IMContextWrapper.h   |  65 ++++++---
 2 files changed, 203 insertions(+), 101 deletions(-)

diff --git a/widget/gtk/IMContextWrapper.cpp b/widget/gtk/IMContextWrapper.cpp
index bb268da75dc2..ba64e3c25a9e 100644
--- a/widget/gtk/IMContextWrapper.cpp
+++ b/widget/gtk/IMContextWrapper.cpp
@@ -175,6 +175,8 @@ IMContextWrapper::IMContextWrapper(nsWindow* aOwnerWindow)
     , mProcessingKeyEvent(nullptr)
     , mCompositionState(eCompositionState_NotComposing)
     , mIsIMFocused(false)
+    , mFallbackToKeyEvent(false)
+    , mKeyboardEventWasDispatched(false)
     , mIsDeletingSurrounding(false)
     , mLayoutChanged(false)
     , mSetCursorPositionOnKeyEvent(true)
@@ -484,7 +486,7 @@ IMContextWrapper::OnBlurWindow(nsWindow* aWindow)
 bool
 IMContextWrapper::OnKeyEvent(nsWindow* aCaller,
                              GdkEventKey* aEvent,
-                             bool aKeyDownEventWasSent /* = false */)
+                             bool aKeyboardEventWasDispatched /* = false */)
 {
     NS_PRECONDITION(aEvent, "aEvent must be non-null");
 
@@ -494,10 +496,10 @@ IMContextWrapper::OnKeyEvent(nsWindow* aCaller,
     }
 
     MOZ_LOG(gGtkIMLog, LogLevel::Info,
-        ("0x%p OnKeyEvent(aCaller=0x%p, aKeyDownEventWasSent=%s), "
+        ("0x%p OnKeyEvent(aCaller=0x%p, aKeyboardEventWasDispatched=%s), "
          "mCompositionState=%s, current context=0x%p, active context=0x%p, "
          "aEvent(0x%p): { type=%s, keyval=%s, unicode=0x%X }",
-         this, aCaller, ToChar(aKeyDownEventWasSent),
+         this, aCaller, ToChar(aKeyboardEventWasDispatched),
          GetCompositionStateName(), GetCurrentContext(), GetActiveContext(),
          aEvent, GetEventType(aEvent), gdk_keyval_name(aEvent->keyval),
          gdk_keyval_to_unicode(aEvent->keyval)));
@@ -525,49 +527,51 @@ IMContextWrapper::OnKeyEvent(nsWindow* aCaller,
         mSetCursorPositionOnKeyEvent = false;
     }
 
-    mKeyDownEventWasSent = aKeyDownEventWasSent;
-    mFilterKeyEvent = true;
+    mKeyboardEventWasDispatched = aKeyboardEventWasDispatched;
+    mFallbackToKeyEvent = false;
     mProcessingKeyEvent = aEvent;
     gboolean isFiltered =
         gtk_im_context_filter_keypress(currentContext, aEvent);
-    mProcessingKeyEvent = nullptr;
 
-    // We filter the key event if the event was not committed (because
-    // it's probably part of a composition) or if the key event was
-    // committed _and_ changed.  This way we still let key press
-    // events go through as simple key press events instead of
-    // composed characters.
-    bool filterThisEvent = isFiltered && mFilterKeyEvent;
+    // The caller of this shouldn't handle aEvent anymore if we've dispatched
+    // composition events or modified content with other events.
+    bool filterThisEvent = isFiltered && !mFallbackToKeyEvent;
 
-    if (IsComposingOnCurrentContext() && !isFiltered) {
-        if (aEvent->type == GDK_KEY_PRESS) {
-            if (!mDispatchedCompositionString.IsEmpty()) {
-                // If there is composition string, we shouldn't dispatch
-                // any keydown events during composition.
-                filterThisEvent = true;
-            } else {
-                // A Hangul input engine for SCIM doesn't emit preedit_end
-                // signal even when composition string becomes empty.  On the
-                // other hand, we should allow to make composition with empty
-                // string for other languages because there *might* be such
-                // IM.  For compromising this issue, we should dispatch
-                // compositionend event, however, we don't need to reset IM
-                // actually.
-                DispatchCompositionCommitEvent(currentContext, &EmptyString());
-                filterThisEvent = false;
-            }
-        } else {
-            // Key release event may not be consumed by IM, however, we
-            // shouldn't dispatch any keyup event during composition.
-            filterThisEvent = true;
-        }
+    if (IsComposingOnCurrentContext() && !isFiltered &&
+        aEvent->type == GDK_KEY_PRESS &&
+        mDispatchedCompositionString.IsEmpty()) {
+        // A Hangul input engine for SCIM doesn't emit preedit_end
+        // signal even when composition string becomes empty.  On the
+        // other hand, we should allow to make composition with empty
+        // string for other languages because there *might* be such
+        // IM.  For compromising this issue, we should dispatch
+        // compositionend event, however, we don't need to reset IM
+        // actually.
+        // NOTE: Don't dispatch key events as "processed by IME" since
+        // we need to dispatch keyboard events as IME wasn't handled it.
+        mProcessingKeyEvent = nullptr;
+        DispatchCompositionCommitEvent(currentContext, &EmptyString());
+        mProcessingKeyEvent = aEvent;
+        // In this case, even though we handle the keyboard event here,
+        // but we should dispatch keydown event as
+        filterThisEvent = false;
     }
 
+    // If IME handled the key event but we've not dispatched eKeyDown nor
+    // eKeyUp event yet, we need to dispatch here because the caller won't
+    // do it.
+    if (filterThisEvent) {
+        MaybeDispatchKeyEventAsProcessedByIME();
+        // Be aware, the widget might have been gone here.
+    }
+
+    mProcessingKeyEvent = nullptr;
+
     MOZ_LOG(gGtkIMLog, LogLevel::Debug,
         ("0x%p   OnKeyEvent(), succeeded, filterThisEvent=%s "
-         "(isFiltered=%s, mFilterKeyEvent=%s), mCompositionState=%s",
+         "(isFiltered=%s, mFallbackToKeyEvent=%s), mCompositionState=%s",
          this, ToChar(filterThisEvent), ToChar(isFiltered),
-         ToChar(mFilterKeyEvent), GetCompositionStateName()));
+         ToChar(mFallbackToKeyEvent), GetCompositionStateName()));
 
     return filterThisEvent;
 }
@@ -1302,11 +1306,14 @@ IMContextWrapper::OnCommitCompositionNative(GtkIMContext* aContext,
     }
 
     // If IME doesn't change their keyevent that generated this commit,
-    // don't send it through XIM - just send it as a normal key press
-    // event.
+    // we should treat that IME didn't handle the key event because
+    // web applications want to receive "keydown" and "keypress" event
+    // in such case.
     // NOTE: While a key event is being handled, this might be caused on
     // current context.  Otherwise, this may be caused on active context.
-    if (!IsComposingOn(aContext) && mProcessingKeyEvent &&
+    if (!IsComposingOn(aContext) &&
+        mProcessingKeyEvent &&
+        mProcessingKeyEvent->type == GDK_KEY_PRESS &&
         aContext == GetCurrentContext()) {
         char keyval_utf8[8]; /* should have at least 6 bytes of space */
         gint keyval_utf8_len;
@@ -1321,7 +1328,9 @@ IMContextWrapper::OnCommitCompositionNative(GtkIMContext* aContext,
                 ("0x%p   OnCommitCompositionNative(), "
                  "we'll send normal key event",
                  this));
-            mFilterKeyEvent = false;
+            // In this case, eKeyDown and eKeyPress event should be dispatched
+            // by the caller of OnKeyEvent().
+            mFallbackToKeyEvent = true;
             return;
         }
     }
@@ -1355,6 +1364,65 @@ IMContextWrapper::GetCompositionString(GtkIMContext* aContext,
     g_free(preedit_string);
 }
 
+bool
+IMContextWrapper::MaybeDispatchKeyEventAsProcessedByIME()
+{
+    if (!mProcessingKeyEvent || mKeyboardEventWasDispatched ||
+        !mLastFocusedWindow) {
+        return true;
+    }
+
+    // A "keydown" or "keyup" event handler may change focus with the
+    // following event.  In such case, we need to cancel this composition.
+    // So, we need to store IM context now because mComposingContext may be
+    // overwritten with different context if calling this method recursively.
+    // Note that we don't need to grab the context here because |context|
+    // will be used only for checking if it's same as mComposingContext.
+    GtkIMContext* oldCurrentContext = GetCurrentContext();
+    GtkIMContext* oldComposingContext = mComposingContext;
+
+    RefPtr<nsWindow> lastFocusedWindow(mLastFocusedWindow);
+    mKeyboardEventWasDispatched = true;
+
+    // FYI: We should ignore if default of preceding keydown or keyup event is
+    //      prevented since even on the other browsers, web applications
+    //      cannot cancel the following composition event.
+    //      Spec bug: https://github.com/w3c/uievents/issues/180
+    bool isCancelled;
+    lastFocusedWindow->DispatchKeyDownOrKeyUpEvent(mProcessingKeyEvent, true,
+                                                   &isCancelled);
+    MOZ_LOG(gGtkIMLog, LogLevel::Debug,
+        ("0x%p   MaybeDispatchKeyEventAsProcessedByIME(), keydown or keyup "
+         "event is dispatched",
+         this));
+    if (lastFocusedWindow->IsDestroyed() ||
+        lastFocusedWindow != mLastFocusedWindow) {
+        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+            ("0x%p   MaybeDispatchKeyEventAsProcessedByIME(), Warning, the "
+             "focused widget was destroyed/changed by a key event",
+             this));
+        return false;
+    }
+
+    // If the dispatched keydown event caused moving focus and that also
+    // caused changing active context, we need to cancel composition here.
+    if (GetCurrentContext() != oldCurrentContext) {
+        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+            ("0x%p   MaybeDispatchKeyEventAsProcessedByIME(), Warning, the key "
+             "event causes changing active IM context",
+             this));
+        if (mComposingContext == oldComposingContext) {
+            // Only when the context is still composing, we should call
+            // ResetIME() here.  Otherwise, it should've already been
+            // cleaned up.
+            ResetIME();
+        }
+        return false;
+    }
+
+    return true;
+}
+
 bool
 IMContextWrapper::DispatchCompositionStart(GtkIMContext* aContext)
 {
@@ -1399,52 +1467,16 @@ IMContextWrapper::DispatchCompositionStart(GtkIMContext* aContext)
     mCompositionStart = mSelection.mOffset;
     mDispatchedCompositionString.Truncate();
 
-    if (mProcessingKeyEvent && !mKeyDownEventWasSent &&
-        mProcessingKeyEvent->type == GDK_KEY_PRESS) {
-        // A keydown event handler may change focus with the following keydown
-        // event.  In such case, we need to cancel this composition.  So, we
-        // need to store IM context now because mComposingContext may be
-        // overwritten with different context if calling this method
-        // recursively.
-        // Note that we don't need to grab the context here because |context|
-        // will be used only for checking if it's same as mComposingContext.
-        GtkIMContext* context = mComposingContext;
-
-        // If this composition is started by a native keydown event, we need to
-        // dispatch our keydown event here (before composition start).
-        // Note that make the preceding eKeyDown event marked as "processed
-        // by IME" for compatibility with Chromium.
-        bool isCancelled;
-        mLastFocusedWindow->DispatchKeyDownOrKeyUpEvent(mProcessingKeyEvent,
-                                                        true, &isCancelled);
-        MOZ_LOG(gGtkIMLog, LogLevel::Debug,
-            ("0x%p   DispatchCompositionStart(), preceding keydown event is "
-             "dispatched",
+    // If this composition is started by a key press, we need to dispatch
+    // eKeyDown or eKeyUp event before dispatching eCompositionStart event.
+    // Note that dispatching a keyboard event which is marked as "processed
+    // by IME" is okay since Chromium also dispatches keyboard event as so.
+    if (!MaybeDispatchKeyEventAsProcessedByIME()) {
+        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+            ("0x%p   DispatchCompositionStart(), Warning, "
+             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
              this));
-        if (lastFocusedWindow->IsDestroyed() ||
-            lastFocusedWindow != mLastFocusedWindow) {
-            MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-                ("0x%p   DispatchCompositionStart(), Warning, the focused "
-                 "widget was destroyed/changed by keydown event",
-                 this));
-            return false;
-        }
-
-        // If the dispatched keydown event caused moving focus and that also
-        // caused changing active context, we need to cancel composition here.
-        if (GetCurrentContext() != context) {
-            MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-                ("0x%p   DispatchCompositionStart(), Warning, the preceding "
-                 "keydown event causes changing active IM context",
-                 this));
-            if (mComposingContext == context) {
-                // Only when the context is still composing, we should call
-                // ResetIME() here.  Otherwise, it should've already been
-                // cleaned up.
-                ResetIME();
-            }
-            return false;
-        }
+        return false;
     }
 
     RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
@@ -1502,6 +1534,15 @@ IMContextWrapper::DispatchCompositionChangeEvent(
             return false;
         }
     }
+    // If this composition string change caused by a key press, we need to
+    // dispatch eKeyDown or eKeyUp before dispatching eCompositionChange event.
+    else if (!MaybeDispatchKeyEventAsProcessedByIME()) {
+        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+            ("0x%p   DispatchCompositionChangeEvent(), Warning, "
+             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
+             this));
+        return false;
+    }
 
     RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
     nsresult rv = dispatcher->BeginNativeInputTransaction();
@@ -1591,6 +1632,14 @@ IMContextWrapper::DispatchCompositionCommitEvent(
         return false;
     }
 
+    // TODO: We need special care to handle request to commit composition
+    //       by content while we're committing composition because we have
+    //       commit string information now but IME may not have composition
+    //       anymore.  Therefore, we may not be able to handle commit as
+    //       expected.  However, this is rare case because this situation
+    //       never occurs with remote content.  So, it's okay to fix this
+    //       issue later.  (Perhaps, TextEventDisptcher should do it for
+    //       all platforms.  E.g., creating WillCommitComposition()?)
     if (!IsComposing()) {
         if (!aCommitString || aCommitString->IsEmpty()) {
             MOZ_LOG(gGtkIMLog, LogLevel::Error,
@@ -1607,6 +1656,16 @@ IMContextWrapper::DispatchCompositionCommitEvent(
             return false;
         }
     }
+    // If this commit caused by a key press, we need to dispatch eKeyDown or
+    // eKeyUp before dispatching composition events.
+    else if (!MaybeDispatchKeyEventAsProcessedByIME()) {
+        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+            ("0x%p   DispatchCompositionCommitEvent(), Warning, "
+             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
+             this));
+        mCompositionState = eCompositionState_NotComposing;
+        return false;
+    }
 
     RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
     nsresult rv = dispatcher->BeginNativeInputTransaction();
@@ -2301,6 +2360,16 @@ IMContextWrapper::DeleteText(GtkIMContext* aContext,
         return NS_ERROR_FAILURE;
     }
 
+    // If this deleting text caused by a key press, we need to dispatch
+    // eKeyDown or eKeyUp before dispatching eContentCommandDelete event.
+    if (!MaybeDispatchKeyEventAsProcessedByIME()) {
+        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+            ("0x%p   DeleteText(), Warning, "
+             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
+             this));
+        return NS_ERROR_FAILURE;
+    }
+
     // Delete the selection
     WidgetContentCommandEvent contentCommandEvent(true, eContentCommandDelete,
                                                   mLastFocusedWindow);
diff --git a/widget/gtk/IMContextWrapper.h b/widget/gtk/IMContextWrapper.h
index 17c758092410..241319cee9ea 100644
--- a/widget/gtk/IMContextWrapper.h
+++ b/widget/gtk/IMContextWrapper.h
@@ -65,13 +65,26 @@ public:
     void OnSelectionChange(nsWindow* aCaller,
                            const IMENotification& aIMENotification);
 
-    // OnKeyEvent is called when aWindow gets a native key press event or a
-    // native key release event.  If this returns TRUE, the key event was
-    // filtered by IME.  Otherwise, this returns FALSE.
-    // NOTE: When the keypress event starts composition, this returns TRUE but
-    //       this dispatches keydown event before compositionstart event.
+    /**
+     * OnKeyEvent() is called when aWindow gets a native key press event or a
+     * native key release event.  If this returns true, the key event was
+     * filtered by IME.  Otherwise, this returns false.
+     * NOTE: When the native key press event starts composition, this returns
+     *       true but dispatches an eKeyDown event or eKeyUp event before
+     *       dispatching composition events or content command event.
+     *
+     * @param aWindow                       A window on which user operate the
+     *                                      key.
+     * @param aEvent                        A native key press or release
+     *                                      event.
+     * @param aKeyboardEventWasDispatched   true if eKeyDown or eKeyUp event
+     *                                      for aEvent has already been
+     *                                      dispatched.  In this case,
+     *                                      this class doesn't dispatch
+     *                                      keyboard event anymore.
+     */
     bool OnKeyEvent(nsWindow* aWindow, GdkEventKey* aEvent,
-                      bool aKeyDownEventWasSent = false);
+                    bool aKeyboardEventWasDispatched = false);
 
     // IME related nsIWidget methods.
     nsresult EndIMEComposition(nsWindow* aCaller);
@@ -263,16 +276,20 @@ protected:
     // mIsIMFocused is set to TRUE when we call gtk_im_context_focus_in(). And
     // it's set to FALSE when we call gtk_im_context_focus_out().
     bool mIsIMFocused;
-    // mFilterKeyEvent is used by OnKeyEvent().  If the commit event should
-    // be processed as simple key event, this is set to TRUE by the commit
-    // handler.
-    bool mFilterKeyEvent;
-    // mKeyDownEventWasSent is used by OnKeyEvent() and
-    // DispatchCompositionStart().  DispatchCompositionStart() dispatches
-    // a keydown event if the composition start is caused by a native
-    // keypress event.  If this is true, the keydown event has been dispatched.
-    // Then, DispatchCompositionStart() doesn't dispatch keydown event.
-    bool mKeyDownEventWasSent;
+    // mFallbackToKeyEvent is set to false when this class starts to handle
+    // a native key event (at that time, mProcessingKeyEvent is set to the
+    // native event).  If active IME just commits composition with a character
+    // which is produced by the key with current keyboard layout, this is set
+    // to true.
+    bool mFallbackToKeyEvent;
+    // mKeyboardEventWasDispatched is used by OnKeyEvent() and
+    // MaybeDispatchKeyEventAsProcessedByIME().
+    // MaybeDispatchKeyEventAsProcessedByIME() dispatches an eKeyDown or
+    // eKeyUp event event if the composition is caused by a native
+    // key press event.  If this is true, a keyboard event has been dispatched
+    // for the native event.  If so, MaybeDispatchKeyEventAsProcessedByIME()
+    // won't dispatch keyboard event anymore.
+    bool mKeyboardEventWasDispatched;
     // mIsDeletingSurrounding is true while OnDeleteSurroundingNative() is
     // trying to delete the surrounding text.
     bool mIsDeletingSurrounding;
@@ -443,11 +460,27 @@ protected:
      *    Following methods dispatch gecko events.  Then, the focused widget
      *    can be destroyed, and also it can be stolen focus.  If they returns
      *    FALSE, callers cannot continue the composition.
+     *      - MaybeDispatchKeyEventAsProcessedByIME
      *      - DispatchCompositionStart
      *      - DispatchCompositionChangeEvent
      *      - DispatchCompositionCommitEvent
      */
 
+    /**
+     * Dispatch an eKeyDown or eKeyUp event whose mKeyCode value is
+     * NS_VK_PROCESSKEY and mKeyNameIndex is KEY_NAME_INDEX_Process if
+     * mProcessingKeyEvent is not nullptr and mKeyboardEventWasDispatched is
+     * still false.  If this dispatches a keyboard event, this sets
+     * mKeyboardEventWasDispatched to true.
+     *
+     * @return                      If the caller can continue to handle
+     *                              composition, returns true.  Otherwise,
+     *                              false.  For example, if focus is moved
+     *                              by dispatched keyboard event, returns
+     *                              false.
+     */
+    bool MaybeDispatchKeyEventAsProcessedByIME();
+
     /**
      * Dispatches a composition start event.
      *

From 2c2365305c9c602fa3ec6d29091101148e918170 Mon Sep 17 00:00:00 2001
From: Masayuki Nakano <masayuki@d-toybox.com>
Date: Fri, 23 Feb 2018 23:09:43 +0900
Subject: [PATCH 33/50] Bug 1343451 - part 4: Make TextInputHandler dispatches
 eKeyDown event with marking it as "processed by IME" r=m_kato

First of all, TextInputHandler::HandleKeyDown() dispatches an eKeyDown event
before sending IME.  This is different behavior from Gecko on the other
platforms and it means TextInputHandler does not know if the eKeyDown event
will be handled by IME.  Therefore, we need to make TextInputHandler dispatch
an eKeyDown event dispatch when it needs to dispatch another event.  Therefore,
this patch makes TextInputHandler not dispatch an eKeyDown even from
its HandleKeyDown() unless it's already has composition (because if it's
already had composition, any eKeyDown event except modifier keys should be
marked as "processed by IME" for compatibility with the other browsers).

For dispatching eKeyDown event only once for a native keydown event,
this patch implements TextInputHandlerBase::MaybeDispatchCurrentKeydownEvent()
to check whether eKeyDown event has already been dispatched for the event
and if it's not so, dispatches eKeyDown event.

Note that on macOS, dead keys are implemented as IME.  However, we need to
treat dead keys as is.  Therefore, if current keydown event is a dead keydown
event, MaybeDispatchCurrentKeydownEvent() should NOT mark dispatching
eKeyDown event and its following eKeyDown event as "processed by IME".

MozReview-Commit-ID: 7epk8wdAznd

--HG--
extra : rebase_source : 4f4e23a8cc5005d8f0da3c35910eba30f8777e6b
---
 widget/cocoa/TextInputHandler.h  |  47 +++-
 widget/cocoa/TextInputHandler.mm | 431 +++++++++++++++++++++++++------
 2 files changed, 400 insertions(+), 78 deletions(-)

diff --git a/widget/cocoa/TextInputHandler.h b/widget/cocoa/TextInputHandler.h
index 1e41c3752822..74e8fec9c581 100644
--- a/widget/cocoa/TextInputHandler.h
+++ b/widget/cocoa/TextInputHandler.h
@@ -243,6 +243,9 @@ public:
    *                              dispatch a Gecko key event.
    * @param aKeyEvent             The result -- a Gecko key event initialized
    *                              from the native key event.
+   * @param aIsProcessedByIME     true if aNativeKeyEvent has been handled
+   *                              by IME (but except if the composition was
+   *                              started with dead key).
    * @param aInsertString         If caller expects that the event will cause
    *                              a character to be input (say in an editor),
    *                              the caller should set this.  Otherwise,
@@ -251,6 +254,7 @@ public:
    *                              characters of aNativeKeyEvent.
    */
   void InitKeyEvent(NSEvent *aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
+                    bool aIsProcessedByIME,
                     const nsAString *aInsertString = nullptr);
 
   /**
@@ -303,6 +307,15 @@ public:
   static CodeNameIndex ComputeGeckoCodeNameIndex(UInt32 aNativeKeyCode,
                                                  UInt32 aKbType);
 
+  /**
+   * TranslateToChar() checks if aNativeKeyEvent is a dead key.
+   *
+   * @param aNativeKeyEvent       A native key event.
+   * @return                      Returns true if the key event is a dead key
+   *                              event.  Otherwise, false.
+   */
+  bool IsDeadKey(NSEvent* aNativeKeyEvent);
+
 protected:
   /**
    * TranslateToString() computes the inputted text from the native keyCode,
@@ -343,7 +356,7 @@ protected:
    * @param aKbType               A native Keyboard Type value.  Typically,
    *                              this is a result of ::LMGetKbdType().
    * @return                      Returns true if the key with specified
-   *                              modifier state isa dead key.  Otherwise,
+   *                              modifier state is a dead key.  Otherwise,
    *                              false.
    */
   bool IsDeadKey(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType);
@@ -433,6 +446,9 @@ public:
    *                              dispatch a Gecko key event.
    * @param aKeyEvent             The result -- a Gecko key event initialized
    *                              from the native key event.
+   * @param aIsProcessedByIME     true if aNativeKeyEvent has been handled
+   *                              by IME (but except if the composition was
+   *                              started with dead key).
    * @param aInsertString         If caller expects that the event will cause
    *                              a character to be input (say in an editor),
    *                              the caller should set this.  Otherwise,
@@ -441,6 +457,7 @@ public:
    *                              characters of aNativeKeyEvent.
    */
   void InitKeyEvent(NSEvent *aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
+                    bool aIsProcessedByIME,
                     const nsAString *aInsertString = nullptr);
 
   /**
@@ -552,6 +569,8 @@ protected:
     // Unique id associated with a keydown / keypress event. It's ok if this
     // wraps over long periods.
     uint32_t mUniqueId;
+    // Whether keydown event was dispatched for mKeyEvent.
+    bool mKeyDownDispatched;
     // Whether keydown event was consumed by web contents or chrome contents.
     bool mKeyDownHandled;
     // Whether keypress event was dispatched for mKeyEvent.
@@ -604,6 +623,7 @@ protected:
       }
       mInsertString = nullptr;
       mInsertedString.Truncate();
+      mKeyDownDispatched = false;
       mKeyDownHandled = false;
       mKeyPressDispatched = false;
       mKeyPressHandled = false;
@@ -617,6 +637,11 @@ protected:
              mCompositionDispatched;
     }
 
+    bool CanDispatchKeyDownEvent() const
+    {
+      return !mKeyDownDispatched;
+    }
+
     bool CanDispatchKeyPressEvent() const
     {
       return !mKeyPressDispatched && !IsDefaultPrevented();
@@ -765,7 +790,8 @@ protected:
     }
 
     void InitKeyEvent(TextInputHandlerBase* aHandler,
-                      WidgetKeyboardEvent& aKeyEvent);
+                      WidgetKeyboardEvent& aKeyEvent,
+                      bool aIsProcessedByIME);
 
     /**
      * GetUnhandledString() returns characters of the event which have not been
@@ -1059,6 +1085,7 @@ public:
   NSRange MarkedRange();
 
   bool IsIMEComposing() { return mIsIMEComposing; }
+  bool IsDeadKeyComposing() { return mIsDeadKeyComposing; }
   bool IsIMEOpened();
   bool IsIMEEnabled() { return mIsIMEEnabled; }
   bool IsASCIICapableOnly() { return mIsASCIICapableOnly; }
@@ -1112,6 +1139,19 @@ protected:
   void InsertTextAsCommittingComposition(NSAttributedString* aAttrString,
                                          NSRange* aReplacementRange);
 
+  /**
+   * MaybeDispatchCurrentKeydownEvent() dispatches eKeyDown event for current
+   * key event.  If eKeyDown for current key event has already been dispatched,
+   * this does nothing.
+   *
+   * @param aIsProcessedByIME   true if current key event is handled by IME.
+   * @return                    true if the caller can continue to handle
+   *                            current key event.  Otherwise, false.  E.g.,
+   *                            focus is moved, the widget has been destroyed
+   *                            or something.
+   */
+  bool MaybeDispatchCurrentKeydownEvent(bool aIsProcessedByIME);
+
 private:
   // If mIsIMEComposing is true, the composition string is stored here.
   NSString* mIMECompositionString;
@@ -1125,6 +1165,9 @@ private:
   mozilla::WritingMode mWritingMode;
 
   bool mIsIMEComposing;
+  // If the composition started with dead key, mIsDeadKeyComposing is set to
+  // true.
+  bool mIsDeadKeyComposing;
   bool mIsIMEEnabled;
   bool mIsASCIICapableOnly;
   bool mIgnoreIMECommit;
diff --git a/widget/cocoa/TextInputHandler.mm b/widget/cocoa/TextInputHandler.mm
index 106ef0e91f52..eb2057a85a08 100644
--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -399,6 +399,84 @@ TISInputSourceWrapper::TranslateToChar(UInt32 aKeyCode, UInt32 aModifiers,
   return static_cast<uint32_t>(str.CharAt(0));
 }
 
+bool
+TISInputSourceWrapper::IsDeadKey(NSEvent* aNativeKeyEvent)
+{
+  if ([[aNativeKeyEvent characters] length]) {
+    return false;
+  }
+
+  // Assmue that if control key or command key is pressed, it's not a dead key.
+  NSUInteger cocoaState = [aNativeKeyEvent modifierFlags];
+  if (cocoaState & (NSControlKeyMask | NSCommandKeyMask)) {
+    return false;
+  }
+
+  UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
+  switch (nativeKeyCode) {
+    case kVK_ANSI_A:
+    case kVK_ANSI_B:
+    case kVK_ANSI_C:
+    case kVK_ANSI_D:
+    case kVK_ANSI_E:
+    case kVK_ANSI_F:
+    case kVK_ANSI_G:
+    case kVK_ANSI_H:
+    case kVK_ANSI_I:
+    case kVK_ANSI_J:
+    case kVK_ANSI_K:
+    case kVK_ANSI_L:
+    case kVK_ANSI_M:
+    case kVK_ANSI_N:
+    case kVK_ANSI_O:
+    case kVK_ANSI_P:
+    case kVK_ANSI_Q:
+    case kVK_ANSI_R:
+    case kVK_ANSI_S:
+    case kVK_ANSI_T:
+    case kVK_ANSI_U:
+    case kVK_ANSI_V:
+    case kVK_ANSI_W:
+    case kVK_ANSI_X:
+    case kVK_ANSI_Y:
+    case kVK_ANSI_Z:
+    case kVK_ANSI_1:
+    case kVK_ANSI_2:
+    case kVK_ANSI_3:
+    case kVK_ANSI_4:
+    case kVK_ANSI_5:
+    case kVK_ANSI_6:
+    case kVK_ANSI_7:
+    case kVK_ANSI_8:
+    case kVK_ANSI_9:
+    case kVK_ANSI_0:
+    case kVK_ANSI_Equal:
+    case kVK_ANSI_Minus:
+    case kVK_ANSI_RightBracket:
+    case kVK_ANSI_LeftBracket:
+    case kVK_ANSI_Quote:
+    case kVK_ANSI_Semicolon:
+    case kVK_ANSI_Backslash:
+    case kVK_ANSI_Comma:
+    case kVK_ANSI_Slash:
+    case kVK_ANSI_Period:
+    case kVK_ANSI_Grave:
+    case kVK_JIS_Yen:
+    case kVK_JIS_Underscore:
+      break;
+    default:
+      // Let's assume that dead key can be only a printable key in standard
+      // position.
+      return false;
+  }
+
+  // If TranslateToChar() returns non-zero value, that means that
+  // the key may input a character with different dead key state.
+  UInt32 kbType = GetKbdType();
+  UInt32 carbonState = nsCocoaUtils::ConvertToCarbonModifier(cocoaState);
+  return IsDeadKey(nativeKeyCode, carbonState, kbType);
+}
+
 bool
 TISInputSourceWrapper::IsDeadKey(UInt32 aKeyCode,
                                  UInt32 aModifiers,
@@ -906,17 +984,25 @@ TISInputSourceWrapper::ComputeInsertStringForCharCode(
 void
 TISInputSourceWrapper::InitKeyEvent(NSEvent *aNativeKeyEvent,
                                     WidgetKeyboardEvent& aKeyEvent,
+                                    bool aIsProcessedByIME,
                                     const nsAString *aInsertString)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
+  MOZ_ASSERT(!aIsProcessedByIME || aKeyEvent.mMessage != eKeyPress,
+    "eKeyPress event should not be marked as proccessed by IME");
+
   MOZ_LOG(gLog, LogLevel::Info,
     ("%p TISInputSourceWrapper::InitKeyEvent, aNativeKeyEvent=%p, "
-     "aKeyEvent.mMessage=%s, aInsertString=%p, IsOpenedIMEMode()=%s",
-     this, aNativeKeyEvent, GetGeckoKeyEventType(aKeyEvent), aInsertString,
+     "aKeyEvent.mMessage=%s, aProcessedByIME=%s, aInsertString=%p, "
+     "IsOpenedIMEMode()=%s",
+     this, aNativeKeyEvent, GetGeckoKeyEventType(aKeyEvent),
+     TrueOrFalse(aIsProcessedByIME), aInsertString,
      TrueOrFalse(IsOpenedIMEMode())));
 
-  NS_ENSURE_TRUE(aNativeKeyEvent, );
+  if (NS_WARN_IF(!aNativeKeyEvent)) {
+    return;
+  }
 
   nsCocoaUtils::InitInputEvent(aKeyEvent, aNativeKeyEvent);
 
@@ -945,8 +1031,18 @@ TISInputSourceWrapper::InitKeyEvent(NSEvent *aNativeKeyEvent,
   UInt32 kbType = GetKbdType();
   UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
 
+  // macOS handles dead key as IME.  If the key is first key press of dead
+  // key, we should use KEY_NAME_INDEX_Dead for first (dead) key event.
+  // So, if aIsProcessedByIME is true, it may be dead key.  Let's check
+  // if current key event is a dead key's keydown event.
+  bool isProcessedByIME =
+    aIsProcessedByIME &&
+    !TISInputSourceWrapper::CurrentInputSource().IsDeadKey(aNativeKeyEvent);
+
   aKeyEvent.mKeyCode =
-    ComputeGeckoKeyCode(nativeKeyCode, kbType, aKeyEvent.IsMeta());
+    isProcessedByIME ?
+      NS_VK_PROCESSKEY :
+      ComputeGeckoKeyCode(nativeKeyCode, kbType, aKeyEvent.IsMeta());
 
   switch (nativeKeyCode) {
     case kVK_Command:
@@ -999,7 +1095,9 @@ TISInputSourceWrapper::InitKeyEvent(NSEvent *aNativeKeyEvent,
      this, OnOrOff(aKeyEvent.IsShift()), OnOrOff(aKeyEvent.IsControl()),
      OnOrOff(aKeyEvent.IsAlt()), OnOrOff(aKeyEvent.IsMeta())));
 
-  if (IsPrintableKeyEvent(aNativeKeyEvent)) {
+  if (isProcessedByIME) {
+    aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_Process;
+  } else if (IsPrintableKeyEvent(aNativeKeyEvent)) {
     aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
     // If insertText calls this method, let's use the string.
     if (aInsertString && !aInsertString->IsEmpty() &&
@@ -1628,7 +1726,7 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
       }
 
       WidgetKeyboardEvent imeEvent(true, eKeyDown, widget);
-      currentKeyEvent->InitKeyEvent(this, imeEvent);
+      currentKeyEvent->InitKeyEvent(this, imeEvent, false);
       imeEvent.mPluginTextEventString.Assign(committed);
       nsEventStatus status = nsEventStatus_eIgnore;
       mDispatcher->DispatchKeyboardEvent(eKeyDown, imeEvent, status,
@@ -1637,50 +1735,18 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
     return true;
   }
 
-  NSResponder* firstResponder = [[mView window] firstResponder];
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
 
-  nsresult rv = mDispatcher->BeginNativeInputTransaction();
-  if (NS_WARN_IF(NS_FAILED(rv))) {
-      MOZ_LOG(gLog, LogLevel::Error,
-        ("%p IMEInputHandler::HandleKeyDownEvent, "
-         "FAILED, due to BeginNativeInputTransaction() failure "
-         "at dispatching keydown for ordinal cases", this));
+  // When we're already in a composition, we need always to mark the eKeyDown
+  // event as "processed by IME".  So, let's dispatch eKeyDown event here in
+  // such case.
+  if (IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(true)) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::HandleKeyDownEvent, eKeyDown caused focus move or "
+       "something and canceling the composition", this));
     return false;
   }
 
-  WidgetKeyboardEvent keydownEvent(true, eKeyDown, widget);
-  currentKeyEvent->InitKeyEvent(this, keydownEvent);
-
-  nsEventStatus status = nsEventStatus_eIgnore;
-  mDispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent, status,
-                                     currentKeyEvent);
-  currentKeyEvent->mKeyDownHandled =
-    (status == nsEventStatus_eConsumeNoDefault);
-
-  if (Destroyed()) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p TextInputHandler::HandleKeyDownEvent, "
-       "widget was destroyed by keydown event", this));
-    return currentKeyEvent->IsDefaultPrevented();
-  }
-
-  // The key down event may have shifted the focus, in which
-  // case we should not fire the key press.
-  // XXX This is a special code only on Cocoa widget, why is this needed?
-  if (firstResponder != [[mView window] firstResponder]) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p TextInputHandler::HandleKeyDownEvent, "
-       "view lost focus by keydown event", this));
-    return currentKeyEvent->IsDefaultPrevented();
-  }
-
-  if (currentKeyEvent->IsDefaultPrevented()) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p TextInputHandler::HandleKeyDownEvent, "
-       "keydown event's default is prevented", this));
-    return true;
-  }
-
   // Let Cocoa interpret the key events, caching IsIMEComposing first.
   bool wasComposing = IsIMEComposing();
   bool interpretKeyEventsCalled = false;
@@ -1710,9 +1776,33 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
      "IsIMEComposing()=%s",
      this, TrueOrFalse(wasComposing), TrueOrFalse(IsIMEComposing())));
 
+  if (currentKeyEvent->CanDispatchKeyDownEvent()) {
+    // Dispatch eKeyDown event if nobody has dispatched it yet.
+    // NOTE: Although reaching here means that the native keydown event may
+    //       not be handled by IME.  However, we cannot know if it is.
+    //       For example, Japanese IME of Apple shows candidate window for
+    //       typing window.  They, you can switch the sort order with Tab key.
+    //       However, when you choose "Symbol" of the sort order, there may
+    //       be no candiate words.  In this case, IME handles the Tab key
+    //       actually, but we cannot know it because composition string is
+    //       not updated.  So, let's mark eKeyDown event as "processed by IME"
+    //       when there is composition string.  This is same as Chrome.
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p TextInputHandler::HandleKeyDownEvent, trying to dispatch eKeyDown "
+       "event since it's not yet dispatched",
+       this));
+    if (!MaybeDispatchCurrentKeydownEvent(IsIMEComposing())) {
+      return true; // treat the eKeydDown event as consumed.
+    }
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p TextInputHandler::HandleKeyDownEvent, eKeyDown event has been "
+       "dispatched",
+       this));
+  }
+
   if (currentKeyEvent->CanDispatchKeyPressEvent() &&
       !wasComposing && !IsIMEComposing()) {
-    rv = mDispatcher->BeginNativeInputTransaction();
+    nsresult rv = mDispatcher->BeginNativeInputTransaction();
     if (NS_WARN_IF(NS_FAILED(rv))) {
         MOZ_LOG(gLog, LogLevel::Error,
           ("%p IMEInputHandler::HandleKeyDownEvent, "
@@ -1722,7 +1812,7 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
     }
 
     WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
-    currentKeyEvent->InitKeyEvent(this, keypressEvent);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
 
     // If we called interpretKeyEvents and this isn't normal character input
     // then IME probably ate the event for some reason. We do not want to
@@ -1737,6 +1827,11 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
     //    our default action for this key.
     if (!(interpretKeyEventsCalled &&
           IsNormalCharInputtingEvent(keypressEvent))) {
+      MOZ_LOG(gLog, LogLevel::Info,
+        ("%p TextInputHandler::HandleKeyDownEvent, trying to dispatch "
+         "eKeyPress event since it's not yet dispatched",
+         this));
+      nsEventStatus status = nsEventStatus_eIgnore;
       currentKeyEvent->mKeyPressDispatched =
         mDispatcher->MaybeDispatchKeypressEvents(keypressEvent, status,
                                                  currentKeyEvent);
@@ -1744,7 +1839,8 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
         (status == nsEventStatus_eConsumeNoDefault);
       currentKeyEvent->mKeyPressDispatched = true;
       MOZ_LOG(gLog, LogLevel::Info,
-        ("%p TextInputHandler::HandleKeyDownEvent, keypress event dispatched",
+        ("%p TextInputHandler::HandleKeyDownEvent, eKeyPress event has been "
+         "dispatched",
          this));
     }
   }
@@ -1798,8 +1894,10 @@ TextInputHandler::HandleKeyUpEvent(NSEvent* aNativeEvent)
     return;
   }
 
+  // Neither Chrome for macOS nor Safari marks "keyup" event as "processed by
+  // IME" even during composition.  So, let's follow this behavior.
   WidgetKeyboardEvent keyupEvent(true, eKeyUp, mWidget);
-  InitKeyEvent(aNativeEvent, keyupEvent);
+  InitKeyEvent(aNativeEvent, keyupEvent, false);
 
   KeyEventState currentKeyEvent(aNativeEvent);
   nsEventStatus status = nsEventStatus_eIgnore;
@@ -2143,7 +2241,7 @@ TextInputHandler::DispatchKeyEventForFlagsChanged(NSEvent* aNativeEvent,
      GetKeyNameForNativeKeyCode([aNativeEvent keyCode]), [aNativeEvent keyCode],
      TrueOrFalse(aDispatchKeyDown), TrueOrFalse(IsIMEComposing())));
 
-  if ([aNativeEvent type] != NSFlagsChanged || IsIMEComposing()) {
+  if ([aNativeEvent type] != NSFlagsChanged) {
     return;
   }
 
@@ -2157,9 +2255,11 @@ TextInputHandler::DispatchKeyEventForFlagsChanged(NSEvent* aNativeEvent,
 
   EventMessage message = aDispatchKeyDown ? eKeyDown : eKeyUp;
 
-  // Fire a key event.
+  // Fire a key event for the modifier key.  Note that even if modifier key
+  // is pressed during composition, we shouldn't mark the keyboard event as
+  // "processed by IME" since neither Chrome for macOS nor Safari does it.
   WidgetKeyboardEvent keyEvent(true, message, mWidget);
-  InitKeyEvent(aNativeEvent, keyEvent);
+  InitKeyEvent(aNativeEvent, keyEvent, false);
 
   // Attach a plugin event, in case keyEvent gets dispatched to a plugin.  Only
   // one field is needed -- the type.  The other fields can be constructed as
@@ -2195,13 +2295,16 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
     ("%p TextInputHandler::InsertText, aAttrString=\"%s\", "
      "aReplacementRange=%p { location=%lu, length=%lu }, "
      "IsIMEComposing()=%s, "
-     "keyevent=%p, keydownHandled=%s, keypressDispatched=%s, "
+     "keyevent=%p, keydownDispatched=%s, "
+     "keydownHandled=%s, keypressDispatched=%s, "
      "causedOtherKeyEvents=%s, compositionDispatched=%s",
      this, GetCharacters([aAttrString string]), aReplacementRange,
      static_cast<unsigned long>(aReplacementRange ? aReplacementRange->location : 0),
      static_cast<unsigned long>(aReplacementRange ? aReplacementRange->length : 0),
      TrueOrFalse(IsIMEComposing()),
      currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
+     currentKeyEvent ?
+       TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
      currentKeyEvent ?
@@ -2253,8 +2356,21 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
     if (!currentKeyEvent) {
       return;
     }
-    // Delete the selected range.
+
+    // When current keydown event causes this empty text input, let's
+    // dispatch eKeyDown event before any other events.  Note that if we're
+    // in a composition, we've already dispatched eKeyDown event from
+    // TextInputHandler::HandleKeyDownEvent().
+    // XXX Should we mark this eKeyDown event as "processed by IME"?
     RefPtr<TextInputHandler> kungFuDeathGrip(this);
+    if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+      MOZ_LOG(gLog, LogLevel::Info,
+        ("%p IMEInputHandler::InsertText, eKeyDown caused focus move or "
+         "something and canceling the composition", this));
+      return;
+    }
+
+    // Delete the selected range.
     WidgetContentCommandEvent deleteCommandEvent(true, eContentCommandDelete,
                                                  mWidget);
     DispatchEvent(deleteCommandEvent);
@@ -2303,13 +2419,23 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
     return;
   }
 
+  // This is the normal path to input a character when you press a key.
+  // Let's dispatch eKeyDown event now.
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  if (!MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::InsertText, eKeyDown caused focus move or "
+       "something and canceling the composition", this));
+    return;
+  }
+
   // XXX Shouldn't we hold mDispatcher instead of mWidget?
   RefPtr<nsChildView> widget(mWidget);
   nsresult rv = mDispatcher->BeginNativeInputTransaction();
   if (NS_WARN_IF(NS_FAILED(rv))) {
-      MOZ_LOG(gLog, LogLevel::Error,
-        ("%p IMEInputHandler::HandleKeyUpEvent, "
-         "FAILED, due to BeginNativeInputTransaction() failure", this));
+    MOZ_LOG(gLog, LogLevel::Error,
+      ("%p IMEInputHandler::InsertText, "
+       "FAILED, due to BeginNativeInputTransaction() failure", this));
     return;
   }
 
@@ -2325,7 +2451,7 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
   // the input string.
 
   if (currentKeyEvent) {
-    currentKeyEvent->InitKeyEvent(this, keypressEvent);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
   } else {
     nsCocoaUtils::InitInputEvent(keypressEvent, static_cast<NSEvent*>(nullptr));
     keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
@@ -2391,6 +2517,18 @@ TextInputHandler::HandleCommand(Command aCommand)
     return false;
   }
 
+  // When current keydown event causes this command, let's dispatch
+  // eKeyDown event before any other events.  Note that if we're in a
+  // composition, we've already dispatched eKeyDown event from
+  // TextInputHandler::HandleKeyDownEvent().
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
+       "something and canceling the composition", this));
+    return false;
+  }
+
   // If it's in composition, we cannot dispatch keypress event.
   // Therefore, we should use different approach or give up to handle
   // the command.
@@ -2487,7 +2625,7 @@ TextInputHandler::HandleCommand(Command aCommand)
   if (!dispatchFakeKeyPress) {
     // If we're acutally handling a key press, we should dispatch
     // the keypress event as-is.
-    currentKeyEvent->InitKeyEvent(this, keypressEvent);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
   } else {
     // Otherwise, we should dispatch "fake" keypress event.
     // However, for making it possible to compute edit commands, we need to
@@ -2753,11 +2891,15 @@ TextInputHandler::DoCommandBySelector(const char* aSelector)
 
   MOZ_LOG(gLog, LogLevel::Info,
     ("%p TextInputHandler::DoCommandBySelector, aSelector=\"%s\", "
-     "Destroyed()=%s, keydownHandled=%s, keypressHandled=%s, "
-     "causedOtherKeyEvents=%s",
+     "Destroyed()=%s, keydownDispatched=%s, keydownHandled=%s, "
+     "keypressDispatched=%s, keypressHandled=%s, causedOtherKeyEvents=%s",
      this, aSelector ? aSelector : "", TrueOrFalse(Destroyed()),
+     currentKeyEvent ?
+       TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
+     currentKeyEvent ?
+       TrueOrFalse(currentKeyEvent->mKeyPressDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyPressHandled) : "N/A",
      currentKeyEvent ?
@@ -2769,6 +2911,18 @@ TextInputHandler::DoCommandBySelector(const char* aSelector)
     return Destroyed();
   }
 
+  // When current keydown event causes this command, let's dispatch
+  // eKeyDown event before any other events.  Note that if we're in a
+  // composition, we've already dispatched eKeyDown event from
+  // TextInputHandler::HandleKeyDownEvent().
+  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
+       "something and canceling the composition", this));
+    return true;
+  }
+
   // If the key operation causes this command, should dispatch a keypress
   // event.
   // XXX This must be worng.  Even if this command is caused by the key
@@ -2786,7 +2940,7 @@ TextInputHandler::DoCommandBySelector(const char* aSelector)
     }
 
     WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
-    currentKeyEvent->InitKeyEvent(this, keypressEvent);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
 
     nsEventStatus status = nsEventStatus_eIgnore;
     currentKeyEvent->mKeyPressDispatched =
@@ -3399,6 +3553,11 @@ IMEInputHandler::DispatchCompositionStartEvent()
 
   NS_ASSERTION(!mIsIMEComposing, "There is a composition already");
   mIsIMEComposing = true;
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+  mIsDeadKeyComposing =
+     currentKeyEvent && currentKeyEvent->mKeyEvent &&
+     TISInputSourceWrapper::CurrentInputSource().
+                              IsDeadKey(currentKeyEvent->mKeyEvent);
 
   nsEventStatus status;
   rv = mDispatcher->StartComposition(status);
@@ -3549,7 +3708,7 @@ IMEInputHandler::DispatchCompositionCommitEvent(const nsAString* aCommitString)
     }
   }
 
-  mIsIMEComposing = false;
+  mIsIMEComposing = mIsDeadKeyComposing = false;
   mIMECompositionStart = UINT32_MAX;
   if (mIMECompositionString) {
     [mIMECompositionString release];
@@ -3568,6 +3727,89 @@ IMEInputHandler::DispatchCompositionCommitEvent(const nsAString* aCommitString)
   NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(false);
 }
 
+bool
+IMEInputHandler::MaybeDispatchCurrentKeydownEvent(bool aIsProcessedByIME)
+{
+  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
+
+  if (Destroyed()) {
+    return false;
+  }
+  MOZ_ASSERT(mWidget);
+
+  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
+  if (!currentKeyEvent ||
+      !currentKeyEvent->CanDispatchKeyDownEvent()) {
+    return true;
+  }
+
+  NSEvent* nativeEvent = currentKeyEvent->mKeyEvent;
+  if (NS_WARN_IF(!nativeEvent) ||
+      [nativeEvent type] != NSKeyDown) {
+    return true;
+  }
+
+  MOZ_LOG(gLog, LogLevel::Info,
+    ("%p IMEInputHandler::MaybeDispatchKeydownEvent, aIsProcessedByIME=%s "
+     "currentKeyEvent={ mKeyEvent(%p)={ type=%s, keyCode=%s (0x%X) } }, "
+     "aIsProcesedBy=%s, IsDeadKeyComposing()=%s",
+     this, TrueOrFalse(aIsProcessedByIME), nativeEvent,
+     GetNativeKeyEventType(nativeEvent),
+     GetKeyNameForNativeKeyCode([nativeEvent keyCode]), [nativeEvent keyCode],
+     TrueOrFalse(IsIMEComposing()), TrueOrFalse(IsDeadKeyComposing())));
+
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+  RefPtr<TextEventDispatcher> dispatcher(mDispatcher);
+  nsresult rv = dispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+      MOZ_LOG(gLog, LogLevel::Error,
+        ("%p IMEInputHandler::DispatchKeyEventForFlagsChanged, "
+         "FAILED, due to BeginNativeInputTransaction() failure", this));
+    return false;
+  }
+
+  NSResponder* firstResponder = [[mView window] firstResponder];
+
+  // Mark currentKeyEvent as "dispatched eKeyDown event" and actually do it.
+  currentKeyEvent->mKeyDownDispatched = true;
+
+  RefPtr<nsChildView> widget(mWidget);
+
+  WidgetKeyboardEvent keydownEvent(true, eKeyDown, widget);
+  // Don't mark the eKeyDown event as "processed by IME" if the composition
+  // is started with dead key.
+  currentKeyEvent->InitKeyEvent(this, keydownEvent,
+                                aIsProcessedByIME && !IsDeadKeyComposing());
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  dispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent, status,
+                                    currentKeyEvent);
+  currentKeyEvent->mKeyDownHandled =
+    (status == nsEventStatus_eConsumeNoDefault);
+
+  if (Destroyed()) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::MaybeDispatchKeydownEvent, "
+       "widget was destroyed by keydown event", this));
+    return false;
+  }
+
+  // The key down event may have shifted the focus, in which case, we should
+  // not continue to handle current key sequence and let's commit current
+  // composition.
+  if (firstResponder != [[mView window] firstResponder]) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::MaybeDispatchKeydownEvent, "
+       "view lost focus by keydown event", this));
+    CommitIMEComposition();
+    return false;
+  }
+
+  return true;
+
+  NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(false);
+}
+
 void
 IMEInputHandler::InsertTextAsCommittingComposition(
                    NSAttributedString* aAttrString,
@@ -3596,6 +3838,22 @@ IMEInputHandler::InsertTextAsCommittingComposition(
     return;
   }
 
+  // When current keydown event causes this text input, let's dispatch
+  // eKeyDown event before any other events.  Note that if we're in a
+  // composition, we've already dispatched eKeyDown event from
+  // TextInputHandler::HandleKeyDownEvent().
+  // XXX Should we mark the eKeyDown event as "processed by IME"?
+  //     However, if the key causes two or more Unicode characters as
+  //     UTF-16 string, this is used.  So, perhaps, we need to improve
+  //     HandleKeyDownEvent() before do that.
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p IMEInputHandler::InsertTextAsCommittingComposition, eKeyDown "
+       "caused focus move or something and canceling the composition", this));
+    return;
+  }
+
   // First, commit current composition with the latest composition string if the
   // replacement range is different from marked range.
   if (IsIMEComposing() && aReplacementRange &&
@@ -3610,8 +3868,6 @@ IMEInputHandler::InsertTextAsCommittingComposition(
     }
   }
 
-  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
-
   nsString str;
   nsCocoaUtils::GetStringForNSString([aAttrString string], str);
 
@@ -3658,7 +3914,8 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
      "aReplacementRange=%p { location=%lu, length=%lu }, "
      "Destroyed()=%s, IsIMEComposing()=%s, "
      "mMarkedRange={ location=%lu, length=%lu }, keyevent=%p, "
-     "keydownHandled=%s, keypressDispatched=%s, causedOtherKeyEvents=%s, "
+     "keydownDispatched=%s, keydownHandled=%s, "
+     "keypressDispatched=%s, causedOtherKeyEvents=%s, "
      "compositionDispatched=%s",
      this, GetCharacters([aAttrString string]),
      static_cast<unsigned long>(aSelectedRange.location),
@@ -3669,6 +3926,8 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
      static_cast<unsigned long>(mMarkedRange.location),
      static_cast<unsigned long>(mMarkedRange.length),
      currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
+     currentKeyEvent ?
+       TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
      currentKeyEvent ?
@@ -3678,19 +3937,32 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mCompositionDispatched) : "N/A"));
 
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
   // If SetMarkedText() is called during handling a key press, that means that
   // the key event caused this composition.  So, keypress event shouldn't
   // be dispatched later, let's mark the key event causing composition event.
   if (currentKeyEvent) {
     currentKeyEvent->mCompositionDispatched = true;
+
+    // When current keydown event causes this text input, let's dispatch
+    // eKeyDown event before any other events.  Note that if we're in a
+    // composition, we've already dispatched eKeyDown event from
+    // TextInputHandler::HandleKeyDownEvent().  On the other hand, if we're
+    // not in composition, the key event starts new composition.  So, we
+    // need to mark the eKeyDown event as "processed by IME".
+    if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(true)) {
+      MOZ_LOG(gLog, LogLevel::Info,
+        ("%p IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
+         "something and canceling the composition", this));
+      return;
+    }
   }
 
   if (Destroyed()) {
     return;
   }
 
-  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
-
   // First, commit current composition with the latest composition string if the
   // replacement range is different from marked range.
   if (IsIMEComposing() && aReplacementRange &&
@@ -4147,6 +4419,7 @@ IMEInputHandler::IMEInputHandler(nsChildView* aWidget,
   , mIMECompositionString(nullptr)
   , mIMECompositionStart(UINT32_MAX)
   , mIsIMEComposing(false)
+  , mIsDeadKeyComposing(false)
   , mIsIMEEnabled(true)
   , mIsASCIICapableOnly(false)
   , mIgnoreIMECommit(false)
@@ -4305,13 +4578,15 @@ IMEInputHandler::CommitIMEComposition()
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
-  if (!IsIMEComposing())
-    return;
-
   MOZ_LOG(gLog, LogLevel::Info,
     ("%p IMEInputHandler::CommitIMEComposition, mIMECompositionString=%s",
      this, GetCharacters(mIMECompositionString)));
 
+  // If this is called before dispatching eCompositionStart, IsIMEComposing()
+  // returns false.  Even in such case, we need to commit composition *in*
+  // IME if this is called by preceding eKeyDown event of eCompositionStart.
+  // So, we need to call KillIMEComposition() even when IsIMEComposing()
+  // returns false.
   KillIMEComposition();
 
   if (!IsIMEComposing())
@@ -4585,6 +4860,7 @@ TextInputHandlerBase::DispatchEvent(WidgetGUIEvent& aEvent)
 void
 TextInputHandlerBase::InitKeyEvent(NSEvent *aNativeKeyEvent,
                                    WidgetKeyboardEvent& aKeyEvent,
+                                   bool aIsProcessedByIME,
                                    const nsAString* aInsertString)
 {
   NS_ASSERTION(aNativeKeyEvent, "aNativeKeyEvent must not be NULL");
@@ -4592,11 +4868,12 @@ TextInputHandlerBase::InitKeyEvent(NSEvent *aNativeKeyEvent,
   if (mKeyboardOverride.mOverrideEnabled) {
     TISInputSourceWrapper tis;
     tis.InitByLayoutID(mKeyboardOverride.mKeyboardLayout, true);
-    tis.InitKeyEvent(aNativeKeyEvent, aKeyEvent, aInsertString);
+    tis.InitKeyEvent(aNativeKeyEvent, aKeyEvent, aIsProcessedByIME,
+                     aInsertString);
     return;
   }
   TISInputSourceWrapper::CurrentInputSource().
-    InitKeyEvent(aNativeKeyEvent, aKeyEvent, aInsertString);
+    InitKeyEvent(aNativeKeyEvent, aKeyEvent, aIsProcessedByIME, aInsertString);
 }
 
 nsresult
@@ -4889,7 +5166,8 @@ TextInputHandlerBase::EnsureSecureEventInputDisabled()
 void
 TextInputHandlerBase::KeyEventState::InitKeyEvent(
                                        TextInputHandlerBase* aHandler,
-                                       WidgetKeyboardEvent& aKeyEvent)
+                                       WidgetKeyboardEvent& aKeyEvent,
+                                       bool aIsProcessedByIME)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
@@ -4919,7 +5197,8 @@ TextInputHandlerBase::KeyEventState::InitKeyEvent(
   }
 
   aKeyEvent.mUniqueId = mUniqueId;
-  aHandler->InitKeyEvent(nativeEvent, aKeyEvent, mInsertString);
+  aHandler->InitKeyEvent(nativeEvent, aKeyEvent, aIsProcessedByIME,
+                         mInsertString);
 
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }

From bb10e7fbe9772827d1236bed3243ac110f96f6cf Mon Sep 17 00:00:00 2001
From: Masayuki Nakano <masayuki@d-toybox.com>
Date: Tue, 27 Feb 2018 17:24:35 +0900
Subject: [PATCH 34/50] Bug 1343451 - part 5: Make GeckoEditableSupport
 dispatch dummy eKeyDown and eKeyUp event during composition always r=jchen

On Android, GeckoEditableSupport has already dispatched eKeyDown event and
eKeyUp event even during composition.  I.e., the pref which will be enabled
by bug 354358 has already been set to true only on Android.

On the other hand, GeckoEditableSupport does not dispatch them if content
listens to "input", "compositionstart", "compositionupdate" or
"compositionend".  So, different from the other platforms, we cannot test
this behind pref ("dom.keyboardevent.dispatch_during_composition") even in
Nightly.

Therefore, this patch enables new behavior only when it's Nightly build or
early Beta.  And sets mKeyCode and mKeyNameIndex of the dummy KeyboardEvents
to NS_VK_PROCESSKEY and KEY_NAME_INDEX_Process.

MozReview-Commit-ID: Fuy0Ir2xiO5

--HG--
extra : rebase_source : fade31954eaa1be8b7592977095ba8aebdd75104
---
 widget/android/GeckoEditableSupport.cpp | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/widget/android/GeckoEditableSupport.cpp b/widget/android/GeckoEditableSupport.cpp
index 78be01395f2e..3c3517e9d0c8 100644
--- a/widget/android/GeckoEditableSupport.cpp
+++ b/widget/android/GeckoEditableSupport.cpp
@@ -668,7 +668,6 @@ GeckoEditableSupport::OnKeyEvent(int32_t aAction, int32_t aKeyCode,
 /*
  * Send dummy key events for pages that are unaware of input events,
  * to provide web compatibility for pages that depend on key events.
- * Our dummy key events have 0 as the keycode.
  */
 void
 GeckoEditableSupport::SendIMEDummyKeyEvent(nsIWidget* aWidget, EventMessage msg)
@@ -678,7 +677,12 @@ GeckoEditableSupport::SendIMEDummyKeyEvent(nsIWidget* aWidget, EventMessage msg)
 
     WidgetKeyboardEvent event(true, msg, aWidget);
     event.mTime = PR_Now() / 1000;
-    MOZ_ASSERT(event.mKeyCode == 0);
+    // TODO: If we can know scan code of the key event which caused replacing
+    //       composition string, we should set mCodeNameIndex here.  Then,
+    //       we should rename this method because it becomes not a "dummy"
+    //       keyboard event.
+    event.mKeyCode = NS_VK_PROCESSKEY;
+    event.mKeyNameIndex = KEY_NAME_INDEX_Process;
     NS_ENSURE_SUCCESS_VOID(BeginInputTransaction(mDispatcher));
     mDispatcher->DispatchKeyboardEvent(msg, event, status);
 }
@@ -1027,12 +1031,19 @@ GeckoEditableSupport::OnImeReplaceText(int32_t aStart, int32_t aEnd,
         AddIMETextChange(dummyChange);
     }
 
+    // Until fixing bug 354358 in release channel, we should always ignore
+    // "intl.ime.hack.on_ime_unaware_apps.fire_key_events_for_composition"
+    // pref in Nightly and early Beta for testing new regressions.
+#ifndef EARLY_BETA_OR_EARLIER
     if (mInputContext.mMayBeIMEUnaware) {
+#endif // #ifndef EARLY_BETA_OR_EARLIER
         SendIMEDummyKeyEvent(widget, eKeyDown);
         if (!mDispatcher || widget->Destroyed()) {
             return;
         }
+#ifndef EARLY_BETA_OR_EARLIER
     }
+#endif // #ifndef EARLY_BETA_OR_EARLIER
 
     if (composing) {
         mDispatcher->SetPendingComposition(string, mIMERanges);
@@ -1046,10 +1057,18 @@ GeckoEditableSupport::OnImeReplaceText(int32_t aStart, int32_t aEnd,
         return;
     }
 
+    // XXX This works fine if user inputs with virtual keyboard.  However,
+    //     if user inputs with hardware keyboard, keyup event may come later.
+    //     So, perhaps, we need to record actual keyboard events before
+    //     this replacement of composition string.
+#ifndef EARLY_BETA_OR_EARLIER
     if (mInputContext.mMayBeIMEUnaware) {
+#endif // #ifndef EARLY_BETA_OR_EARLIER
         SendIMEDummyKeyEvent(widget, eKeyUp);
         // Widget may be destroyed after dispatching the above event.
+#ifndef EARLY_BETA_OR_EARLIER
     }
+#endif // #ifndef EARLY_BETA_OR_EARLIER
 }
 
 void

From 54fa5bc374b4b43f1a89daaaa1b9cb42c32ab19b Mon Sep 17 00:00:00 2001
From: Simon Sapin <simon.sapin@exyr.org>
Date: Mon, 12 Mar 2018 09:23:52 -0400
Subject: [PATCH 35/50] servo: Merge #20216 - Switch from servo/angle to the
 mozangle crate (from servo:mozangle); r=emilio

https://github.com/servo/mozangle

Source-Repo: https://github.com/servo/servo
Source-Revision: 345c373192a30329c2c4f70631ab0792fc348f7d

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 231fb02d47d97c6a8b437eeb36121fc78570a0ef
---
 servo/Cargo.lock                            | 37 ++++++------
 servo/components/script/Cargo.toml          |  2 +-
 servo/components/script/dom/webglprogram.rs | 64 ++++++++++++++++++---
 servo/components/script/dom/webglshader.rs  |  4 +-
 servo/components/script/lib.rs              |  2 +-
 5 files changed, 81 insertions(+), 28 deletions(-)

diff --git a/servo/Cargo.lock b/servo/Cargo.lock
index cbf5c1a79734..cee5f39c1a82 100644
--- a/servo/Cargo.lock
+++ b/servo/Cargo.lock
@@ -26,15 +26,6 @@ name = "android_injected_glue"
 version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
-[[package]]
-name = "angle"
-version = "0.5.0"
-source = "git+https://github.com/servo/angle?branch=servo#1599c1d067b4ccbe502f660181d08d49d69e26eb"
-dependencies = [
- "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
- "lazy_static 0.2.11 (registry+https://github.com/rust-lang/crates.io-index)",
-]
-
 [[package]]
 name = "ansi_term"
 version = "0.10.2"
@@ -312,8 +303,11 @@ dependencies = [
 
 [[package]]
 name = "cc"
-version = "1.0.1"
+version = "1.0.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "rayon 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
 [[package]]
 name = "cexpr"
@@ -395,7 +389,7 @@ name = "cmake"
 version = "0.1.29"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
 [[package]]
@@ -1332,7 +1326,7 @@ name = "jemalloc-sys"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -1579,7 +1573,7 @@ name = "libz-sys"
 version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -1791,6 +1785,15 @@ name = "mitochondria"
 version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "mozangle"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "mozjs"
 version = "0.1.11"
@@ -2066,7 +2069,7 @@ name = "openssl-sys"
 version = "0.9.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 dependencies = [
- "cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)",
  "libc 0.2.33 (registry+https://github.com/rust-lang/crates.io-index)",
  "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
  "vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2423,7 +2426,6 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "script"
 version = "0.0.1"
 dependencies = [
- "angle 0.5.0 (git+https://github.com/servo/angle?branch=servo)",
  "app_units 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "audio-video-metadata 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "base64 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -2460,6 +2462,7 @@ dependencies = [
  "mime 0.2.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "mime_guess 1.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "mitochondria 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "mozangle 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)",
  "mozjs 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "msg 0.0.1",
  "net_traits 0.0.1",
@@ -3693,7 +3696,6 @@ dependencies = [
 "checksum alloc-no-stdlib 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b21f6ad9c9957eb5d70c3dee16d31c092b3cab339628f821766b05e6833d72b8"
 "checksum android_glue 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "000444226fcff248f2bc4c7625be32c63caccfecc2723a2b9f78a7487a49c407"
 "checksum android_injected_glue 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "80b9e34fcbf29c0563547cb2ecce9b49504597cad6166769b1e4efb45c6c2951"
-"checksum angle 0.5.0 (git+https://github.com/servo/angle?branch=servo)" = "<none>"
 "checksum ansi_term 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6b3568b48b7cefa6b8ce125f9bb4989e52fbcc29ebea88df04cc7c5f12f70455"
 "checksum antidote 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "34fde25430d87a9388dadbe6e34d7f72a462c8b43ac8d309b42b0a8505d7e2a5"
 "checksum app_units 0.6.1 (registry+https://github.com/rust-lang/crates.io-index)" = "c4720c83543de184d9f6add2fdb8e8031543497b8506620884c16e125b493c09"
@@ -3721,7 +3723,7 @@ dependencies = [
 "checksum byteorder 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "652805b7e73fada9d85e9a6682a4abd490cb52d96aeecc12e33a0de34dfd0d23"
 "checksum bytes 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c129aff112dcc562970abb69e2508b40850dd24c274761bb50fb8a0067ba6c27"
 "checksum caseless 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e3261638034d9db4f94a666ebb16494846341ae5a8456c05c1616d66980cf39a"
-"checksum cc 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "2c674f0870e3dbd4105184ea035acb1c32c8ae69939c9e228d2b11bbfe29efad"
+"checksum cc 1.0.5 (registry+https://github.com/rust-lang/crates.io-index)" = "9be26b24e988625409b19736d130f0c7d224f01d06454b5f81d8d23d6c1a618f"
 "checksum cexpr 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "393a5f0088efbe41f9d1fcd062f24e83c278608420e62109feb2c8abee07de7d"
 "checksum cfg-if 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "d4c819a1287eb618df47cc647173c5c4c66ba19d888a6e50d605672aed3140de"
 "checksum cgl 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "86765cb42c2a2c497e142af72517c1b4d7ae5bb2f25dfa77a5c69642f2342d89"
@@ -3839,6 +3841,7 @@ dependencies = [
 "checksum mio 0.6.9 (registry+https://github.com/rust-lang/crates.io-index)" = "9e965267d4d58496fc4f740e9861118367f13570cadf66316ed2c3f2f14d87c7"
 "checksum miow 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "8c1f2f3b1cf331de6896aabf6e9d55dca90356cc9960cca7eaaf408a355ae919"
 "checksum mitochondria 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9de3eca27871df31c33b807f834b94ef7d000956f57aa25c5aed9c5f0aae8f6f"
+"checksum mozangle 0.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "4d916e4f2d39a00eeeb082ceb7c63c741e7c9d4f7915945f9225ae5e3b284092"
 "checksum mozjs 0.1.11 (registry+https://github.com/rust-lang/crates.io-index)" = "199f707066bf05b559ef6e46741c20e4f7bca8ae3a9c9d953d728dbb840f4eaa"
 "checksum mozjs_sys 0.50.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e61a792a125b1364c5ec50255ed8343ce02dc56098f8868dd209d472c8de006a"
 "checksum mp3-metadata 0.3.0 (registry+https://github.com/rust-lang/crates.io-index)" = "4ab5f1d2693586420208d1200ce5a51cd44726f055b635176188137aff42c7de"
diff --git a/servo/components/script/Cargo.toml b/servo/components/script/Cargo.toml
index 3db7e6970113..a82a10df5ff6 100644
--- a/servo/components/script/Cargo.toml
+++ b/servo/components/script/Cargo.toml
@@ -99,4 +99,4 @@ webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 webvr_traits = {path = "../webvr_traits"}
 
 [target.'cfg(not(target_os = "ios"))'.dependencies]
-angle = {git = "https://github.com/servo/angle", branch = "servo"}
+mozangle = "0.1"
diff --git a/servo/components/script/dom/webglprogram.rs b/servo/components/script/dom/webglprogram.rs
index 98b788fc2ae9..f08c40f55004 100644
--- a/servo/components/script/dom/webglprogram.rs
+++ b/servo/components/script/dom/webglprogram.rs
@@ -31,6 +31,46 @@ pub struct WebGLProgram {
     renderer: WebGLMsgSender,
 }
 
+/// ANGLE adds a `_u` prefix to variable names:
+///
+/// https://chromium.googlesource.com/angle/angle/+/855d964bd0d05f6b2cb303f625506cf53d37e94f
+///
+/// To avoid hard-coding this we would need to use the `sh::GetAttributes` and `sh::GetUniforms`
+/// API to look up the `x.name` and `x.mappedName` members,
+/// then build a data structure for bi-directional lookup (so either linear scan or two hashmaps).
+/// Even then, this would probably only support plain variable names like "foo".
+/// Strings passed to e.g. `GetUniformLocation` can be expressions like "foo[0].bar",
+/// with the mapping for that "bar" name in yet another part of ANGLE’s API.
+const ANGLE_NAME_PREFIX: &'static str = "_u";
+
+fn to_name_in_compiled_shader(s: &str) -> String {
+    map_dot_separated(s, |s, mapped| {
+        mapped.push_str(ANGLE_NAME_PREFIX);
+        mapped.push_str(s);
+    })
+}
+
+fn from_name_in_compiled_shader(s: &str) -> String {
+    map_dot_separated(s, |s, mapped| {
+        mapped.push_str(if s.starts_with(ANGLE_NAME_PREFIX) {
+            &s[ANGLE_NAME_PREFIX.len()..]
+        } else {
+            s
+        })
+    })
+}
+
+fn map_dot_separated<F: Fn(&str, &mut String)>(s: &str, f: F) -> String {
+    let mut iter = s.split('.');
+    let mut mapped = String::new();
+    f(iter.next().unwrap(), &mut mapped);
+    for s in iter {
+        mapped.push('.');
+        f(s, &mut mapped);
+    }
+    mapped
+}
+
 impl WebGLProgram {
     fn new_inherited(renderer: WebGLMsgSender,
                      id: WebGLProgramId)
@@ -213,8 +253,10 @@ impl WebGLProgram {
             return Err(WebGLError::InvalidOperation);
         }
 
+        let name = to_name_in_compiled_shader(&name);
+
         self.renderer
-            .send(WebGLCommand::BindAttribLocation(self.id, index, String::from(name)))
+            .send(WebGLCommand::BindAttribLocation(self.id, index, name))
             .unwrap();
         Ok(())
     }
@@ -228,8 +270,10 @@ impl WebGLProgram {
             .send(WebGLCommand::GetActiveUniform(self.id, index, sender))
             .unwrap();
 
-        receiver.recv().unwrap().map(|(size, ty, name)|
-            WebGLActiveInfo::new(self.global().as_window(), size, ty, DOMString::from(name)))
+        receiver.recv().unwrap().map(|(size, ty, name)| {
+            let name = DOMString::from(from_name_in_compiled_shader(&name));
+            WebGLActiveInfo::new(self.global().as_window(), size, ty, name)
+        })
     }
 
     /// glGetActiveAttrib
@@ -242,8 +286,10 @@ impl WebGLProgram {
             .send(WebGLCommand::GetActiveAttrib(self.id, index, sender))
             .unwrap();
 
-        receiver.recv().unwrap().map(|(size, ty, name)|
-            WebGLActiveInfo::new(self.global().as_window(), size, ty, DOMString::from(name)))
+        receiver.recv().unwrap().map(|(size, ty, name)| {
+            let name = DOMString::from(from_name_in_compiled_shader(&name));
+            WebGLActiveInfo::new(self.global().as_window(), size, ty, name)
+        })
     }
 
     /// glGetAttribLocation
@@ -264,9 +310,11 @@ impl WebGLProgram {
             return Ok(None);
         }
 
+        let name = to_name_in_compiled_shader(&name);
+
         let (sender, receiver) = webgl_channel().unwrap();
         self.renderer
-            .send(WebGLCommand::GetAttribLocation(self.id, String::from(name), sender))
+            .send(WebGLCommand::GetAttribLocation(self.id, name, sender))
             .unwrap();
         Ok(receiver.recv().unwrap())
     }
@@ -285,9 +333,11 @@ impl WebGLProgram {
             return Ok(None);
         }
 
+        let name = to_name_in_compiled_shader(&name);
+
         let (sender, receiver) = webgl_channel().unwrap();
         self.renderer
-            .send(WebGLCommand::GetUniformLocation(self.id, String::from(name), sender))
+            .send(WebGLCommand::GetUniformLocation(self.id, name, sender))
             .unwrap();
         Ok(receiver.recv().unwrap())
     }
diff --git a/servo/components/script/dom/webglshader.rs b/servo/components/script/dom/webglshader.rs
index 7d69cb5d56cf..2a6504be5068 100644
--- a/servo/components/script/dom/webglshader.rs
+++ b/servo/components/script/dom/webglshader.rs
@@ -3,7 +3,6 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://www.khronos.org/registry/webgl/specs/latest/1.0/webgl.idl
-use angle::hl::{BuiltInResources, Output, ShaderValidator};
 use canvas_traits::webgl::{WebGLSLVersion, WebGLVersion};
 use canvas_traits::webgl::{webgl_channel, WebGLCommand, WebGLMsgSender, WebGLParameter, WebGLResult, WebGLShaderId};
 use dom::bindings::cell::DomRefCell;
@@ -16,6 +15,7 @@ use dom::webgl_extensions::ext::oesstandardderivatives::OESStandardDerivatives;
 use dom::webglobject::WebGLObject;
 use dom::window::Window;
 use dom_struct::dom_struct;
+use mozangle::shaders::{BuiltInResources, Output, ShaderValidator};
 use std::cell::Cell;
 use std::sync::{ONCE_INIT, Once};
 
@@ -47,7 +47,7 @@ impl WebGLShader {
                      id: WebGLShaderId,
                      shader_type: u32)
                      -> WebGLShader {
-        GLSLANG_INITIALIZATION.call_once(|| ::angle::hl::initialize().unwrap());
+        GLSLANG_INITIALIZATION.call_once(|| ::mozangle::shaders::initialize().unwrap());
         WebGLShader {
             webgl_object: WebGLObject::new_inherited(),
             id: id,
diff --git a/servo/components/script/lib.rs b/servo/components/script/lib.rs
index e28bf016e55b..bccfda96fdb2 100644
--- a/servo/components/script/lib.rs
+++ b/servo/components/script/lib.rs
@@ -21,7 +21,6 @@
 #![plugin(script_plugins)]
 #![cfg_attr(not(feature = "unrooted_must_root_lint"), allow(unknown_lints))]
 
-extern crate angle;
 extern crate app_units;
 extern crate audio_video_metadata;
 extern crate base64;
@@ -64,6 +63,7 @@ extern crate metrics;
 extern crate mime;
 extern crate mime_guess;
 extern crate mitochondria;
+extern crate mozangle;
 #[macro_use]
 extern crate mozjs as js;
 extern crate msg;

From 91f3b91ea814023cff4192a2983abead204daf9c Mon Sep 17 00:00:00 2001
From: Cosmin Sabou <csabou@mozilla.com>
Date: Mon, 12 Mar 2018 16:57:12 +0200
Subject: [PATCH 36/50] Backed out changeset adf758d8cff9 (bug 1423220) for
 frequent mochitest browser chrome failures on
 dom/base/test/browser_bug1303838.js

---
 browser/app/profile/firefox.js | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/browser/app/profile/firefox.js b/browser/app/profile/firefox.js
index 4adfff98f013..7e4816503435 100644
--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -1541,12 +1541,8 @@ pref("browser.tabs.remote.desktopbehavior", true);
 
 // For speculatively warming up tabs to improve perceived
 // performance while using the async tab switcher.
-#if defined(NIGHTLY_BUILD)
-pref("browser.tabs.remote.warmup.enabled", true);
-#else
+// Disabled until bug 1397426 is fixed.
 pref("browser.tabs.remote.warmup.enabled", false);
-#endif
-
 pref("browser.tabs.remote.warmup.maxTabs", 3);
 pref("browser.tabs.remote.warmup.unloadDelayMs", 2000);
 

From 174a52929908026380dbcca4f1bef14e3f988628 Mon Sep 17 00:00:00 2001
From: Sylvestre Ledru <sledru@mozilla.com>
Date: Mon, 12 Mar 2018 12:28:00 +0100
Subject: [PATCH 37/50] Bug 1444852 - nsIFrame::BuildDisplayListForChild Remove
 the init step as the result is unused r=miko

MozReview-Commit-ID: G07Fwu1aw0M

--HG--
extra : rebase_source : 0732665c062587c813ec7002704d23006ee33ccf
---
 layout/generic/nsFrame.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index da7e31278f9e..76bf9bc11c54 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -3741,7 +3741,7 @@ nsIFrame::BuildDisplayListForChild(nsDisplayListBuilder*   aBuilder,
 
   nsDisplayList list;
   nsDisplayList extraPositionedDescendants;
-  const ActiveScrolledRoot* wrapListASR = aBuilder->CurrentActiveScrolledRoot();
+  const ActiveScrolledRoot* wrapListASR;
   bool canSkipWrapList = false;
   if (isStackingContext) {
     if (effects->mMixBlendMode != NS_STYLE_BLEND_NORMAL) {

From 6976f22495398de887b8bcfa6220dcfbaee4e71e Mon Sep 17 00:00:00 2001
From: Anthony Ramine <n.oxyde@gmail.com>
Date: Mon, 12 Mar 2018 10:32:52 -0400
Subject: [PATCH 38/50] servo: Merge #20277 - Enable /webvr/ tests (from
 servo:test-webvr); r=jdm

Source-Repo: https://github.com/servo/servo
Source-Revision: 5feb13ac66eb256db8ef41d75ddf9c6c4e0ecd54

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : 6012f487e04de9e484147daa05702650a8ff36ce
---
 servo/components/script/dom/webidls/VR.webidl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/servo/components/script/dom/webidls/VR.webidl b/servo/components/script/dom/webidls/VR.webidl
index af256286523f..a1092cdb7343 100644
--- a/servo/components/script/dom/webidls/VR.webidl
+++ b/servo/components/script/dom/webidls/VR.webidl
@@ -5,6 +5,7 @@
 // https://w3c.github.io/webvr/#interface-navigator
 [NoInterfaceObject]
 interface VR {
+  [Pref="dom.webvr.enabled"]
   Promise<sequence<VRDisplay>> getDisplays();
   //readonly attribute FrozenArray<VRDisplay> activeVRDisplays;
 };

From a41a01a61f75991a406eb7c595af2f577ed3252b Mon Sep 17 00:00:00 2001
From: Gabriele Svelto <gsvelto@mozilla.com>
Date: Mon, 12 Mar 2018 14:31:05 +0100
Subject: [PATCH 39/50] Bug 1444881 - Make |mach bootstrap| use the latest
 version of Oracle's JDK when bootstrapping Fennec on Gentoo; r=nalexander

MozReview-Commit-ID: BnRJC95sSEr

--HG--
extra : rebase_source : 82db88a83191f7e837c000d3701df8b3ee941259
---
 python/mozboot/mozboot/gentoo.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/python/mozboot/mozboot/gentoo.py b/python/mozboot/mozboot/gentoo.py
index 5a1cdbcae35f..2d4dda27694a 100644
--- a/python/mozboot/mozboot/gentoo.py
+++ b/python/mozboot/mozboot/gentoo.py
@@ -62,7 +62,7 @@ class GentooBootstrapper(StyloInstall, BaseBootstrapper):
         # configuration files and doing so without user supervision is dangerous
         self.run_as_root(['emerge', '--noreplace', '--quiet',
                           '--autounmask-continue', '--ask',
-                          '=dev-java/oracle-jdk-bin-1.8.0.162'])
+                          '=dev-java/oracle-jdk-bin-1.8.0.162-r1'])
 
         from mozboot import android
         android.ensure_android('linux', artifact_mode=artifact_mode,

From a1b559f2fa36e1ff542288758d889179470b1254 Mon Sep 17 00:00:00 2001
From: Mark Banner <standard8@mozilla.com>
Date: Mon, 12 Mar 2018 12:33:32 +0000
Subject: [PATCH 40/50] Bug 1444599 - Fix opening bookmark folders from the
 sidebar by middle/ctrl/cmd clicking. r=mak

MozReview-Commit-ID: 4B611oRaCOH

--HG--
extra : rebase_source : d94fe366e4545bc79a6ff900f34cbb437221cc77
---
 .../components/places/content/sidebarUtils.js |  2 +-
 .../places/tests/browser/browser.ini          |  2 +
 .../browser/browser_sidebar_open_bookmarks.js | 68 +++++++++++++++++++
 3 files changed, 71 insertions(+), 1 deletion(-)
 create mode 100644 browser/components/places/tests/browser/browser_sidebar_open_bookmarks.js

diff --git a/browser/components/places/content/sidebarUtils.js b/browser/components/places/content/sidebarUtils.js
index ec4760cc7196..1ed41de7ea3f 100644
--- a/browser/components/places/content/sidebarUtils.js
+++ b/browser/components/places/content/sidebarUtils.js
@@ -43,7 +43,7 @@ var SidebarUtils = {
     var openInTabs = isContainer &&
                      (aEvent.button == 1 ||
                       (aEvent.button == 0 && modifKey)) &&
-                     PlacesUtils.hasChildURIs(tbo.view.nodeForTreeIndex(cell.row));
+                     PlacesUtils.hasChildURIs(aTree.view.nodeForTreeIndex(cell.row));
 
     if (aEvent.button == 0 && isContainer && !openInTabs) {
       tbo.view.toggleOpenState(cell.row);
diff --git a/browser/components/places/tests/browser/browser.ini b/browser/components/places/tests/browser/browser.ini
index 85e4c2c0badd..cfc8d90adbce 100644
--- a/browser/components/places/tests/browser/browser.ini
+++ b/browser/components/places/tests/browser/browser.ini
@@ -103,6 +103,8 @@ skip-if = (os == 'win' && ccov) # Bug 1423667
 [browser_remove_bookmarks.js]
 skip-if = (os == 'win' && ccov) # Bug 1423667
 subsuite = clipboard
+[browser_sidebar_open_bookmarks.js]
+skip-if = (os == 'win' && ccov) # Bug 1423667
 [browser_sidebarpanels_click.js]
 skip-if = (os == 'win' && ccov) || (os == "mac" && debug) # Bug 1423667
 [browser_sort_in_library.js]
diff --git a/browser/components/places/tests/browser/browser_sidebar_open_bookmarks.js b/browser/components/places/tests/browser/browser_sidebar_open_bookmarks.js
new file mode 100644
index 000000000000..9ded308a301d
--- /dev/null
+++ b/browser/components/places/tests/browser/browser_sidebar_open_bookmarks.js
@@ -0,0 +1,68 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+var gBms;
+
+add_task(async function setup() {
+  gBms = await PlacesUtils.bookmarks.insertTree({
+    guid: PlacesUtils.bookmarks.unfiledGuid,
+    children: [{
+      title: "bm1",
+      url: "about:buildconfig"
+    }, {
+      title: "bm2",
+      url: "about:mozilla",
+    }]
+  });
+
+  registerCleanupFunction(async () => {
+    await PlacesUtils.bookmarks.eraseEverything();
+  });
+});
+
+add_task(async function test_open_bookmark_from_sidebar() {
+  let tab = await BrowserTestUtils.openNewForegroundTab(gBrowser);
+
+  await withSidebarTree("bookmarks", async (tree) => {
+    tree.selectItems([gBms[0].guid]);
+
+    let loadedPromise = BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser,
+      false, gBms[0].url
+    );
+
+    tree.controller.doCommand("placesCmd_open");
+
+    await loadedPromise;
+
+    // An assert to make the test happy.
+    Assert.ok(true, "The bookmark was loaded successfully.");
+  });
+
+  await BrowserTestUtils.removeTab(tab);
+});
+
+add_task(async function test_open_bookmark_folder_from_sidebar() {
+  await withSidebarTree("bookmarks", async (tree) => {
+    tree.selectItems([PlacesUtils.bookmarks.virtualUnfiledGuid]);
+
+    Assert.equal(tree.view.selection.getRangeCount(), 1,
+      "Should only have one range selected");
+
+    let loadedPromises = [];
+
+    for (let bm of gBms) {
+      loadedPromises.push(BrowserTestUtils.waitForNewTab(gBrowser,
+        bm.url, false, true));
+    }
+
+    synthesizeClickOnSelectedTreeCell(tree, {button: 1});
+
+   let tabs = await Promise.all(loadedPromises);
+
+    for (let tab of tabs) {
+      await BrowserTestUtils.removeTab(tab);
+    }
+  });
+});

From 462b445081e488be51afdfd103f039610ae44f7c Mon Sep 17 00:00:00 2001
From: Cosmin Sabou <csabou@mozilla.com>
Date: Mon, 12 Mar 2018 18:07:46 +0200
Subject: [PATCH 41/50] Backed out 6 changesets (bug 1343451) for mochitest
 android perma failures on testInputConnection.

Backed out changeset e07105d9698e (bug 1343451)
Backed out changeset dc4a2a5932c3 (bug 1343451)
Backed out changeset 9561ed261d04 (bug 1343451)
Backed out changeset 84a5ec921442 (bug 1343451)
Backed out changeset b34d48936db8 (bug 1343451)
Backed out changeset 4dce7ab14f71 (bug 1343451)
---
 dom/events/VirtualKeyCodeList.h         |   3 -
 dom/webidl/KeyEvent.webidl              |   6 -
 widget/NativeKeyToDOMKeyName.h          |   3 -
 widget/android/GeckoEditableSupport.cpp |  23 +-
 widget/cocoa/TextInputHandler.h         |  47 +--
 widget/cocoa/TextInputHandler.mm        | 431 +++++-------------------
 widget/gtk/IMContextWrapper.cpp         | 241 +++++--------
 widget/gtk/IMContextWrapper.h           |  65 +---
 widget/gtk/nsGtkKeyUtils.cpp            |  16 +-
 widget/gtk/nsGtkKeyUtils.h              |   4 +-
 widget/gtk/nsWindow.cpp                 |  39 ++-
 widget/gtk/nsWindow.h                   |  18 +-
 widget/tests/test_keycodes.xul          |   4 +-
 widget/windows/KeyboardLayout.cpp       |   2 +-
 14 files changed, 215 insertions(+), 687 deletions(-)

diff --git a/dom/events/VirtualKeyCodeList.h b/dom/events/VirtualKeyCodeList.h
index 6660182fe7cd..40615947ef8f 100644
--- a/dom/events/VirtualKeyCodeList.h
+++ b/dom/events/VirtualKeyCodeList.h
@@ -212,9 +212,6 @@ DEFINE_VK_INTERNAL(_ALTGR)
 
 DEFINE_VK_INTERNAL(_WIN_ICO_HELP)
 DEFINE_VK_INTERNAL(_WIN_ICO_00)
-
-DEFINE_VK_INTERNAL(_PROCESSKEY)
-
 DEFINE_VK_INTERNAL(_WIN_ICO_CLEAR)
 DEFINE_VK_INTERNAL(_WIN_OEM_RESET)
 DEFINE_VK_INTERNAL(_WIN_OEM_JUMP)
diff --git a/dom/webidl/KeyEvent.webidl b/dom/webidl/KeyEvent.webidl
index 6fd66afc21d9..abb4b6a34285 100644
--- a/dom/webidl/KeyEvent.webidl
+++ b/dom/webidl/KeyEvent.webidl
@@ -195,12 +195,6 @@ interface KeyEvent
   // for compatibility with the other web browsers on Windows.
   const unsigned long DOM_VK_WIN_ICO_HELP    = 0xE3;
   const unsigned long DOM_VK_WIN_ICO_00      = 0xE4;
-
-  // IME processed key.
-  const unsigned long DOM_VK_PROCESSKEY      = 0xE5;
-
-  // OEM specific virtual keyCode of Windows should pass through DOM keyCode
-  // for compatibility with the other web browsers on Windows.
   const unsigned long DOM_VK_WIN_ICO_CLEAR   = 0xE6;
   const unsigned long DOM_VK_WIN_OEM_RESET   = 0xE9;
   const unsigned long DOM_VK_WIN_OEM_JUMP    = 0xEA;
diff --git a/widget/NativeKeyToDOMKeyName.h b/widget/NativeKeyToDOMKeyName.h
index bfd5baa948b3..db0d73da69aa 100644
--- a/widget/NativeKeyToDOMKeyName.h
+++ b/widget/NativeKeyToDOMKeyName.h
@@ -529,9 +529,6 @@ KEY_MAP_ANDROID (NonConvert, AKEYCODE_MUHENKAN)
 // PreviousCandidate
 KEY_MAP_GTK     (PreviousCandidate, GDK_PreviousCandidate) // OADG 109, Mae Koho
 
-// Process
-KEY_MAP_WIN     (Process, VK_PROCESSKEY)
-
 // SingleCandidate
 KEY_MAP_GTK     (SingleCandidate, GDK_SingleCandidate)
 
diff --git a/widget/android/GeckoEditableSupport.cpp b/widget/android/GeckoEditableSupport.cpp
index 3c3517e9d0c8..78be01395f2e 100644
--- a/widget/android/GeckoEditableSupport.cpp
+++ b/widget/android/GeckoEditableSupport.cpp
@@ -668,6 +668,7 @@ GeckoEditableSupport::OnKeyEvent(int32_t aAction, int32_t aKeyCode,
 /*
  * Send dummy key events for pages that are unaware of input events,
  * to provide web compatibility for pages that depend on key events.
+ * Our dummy key events have 0 as the keycode.
  */
 void
 GeckoEditableSupport::SendIMEDummyKeyEvent(nsIWidget* aWidget, EventMessage msg)
@@ -677,12 +678,7 @@ GeckoEditableSupport::SendIMEDummyKeyEvent(nsIWidget* aWidget, EventMessage msg)
 
     WidgetKeyboardEvent event(true, msg, aWidget);
     event.mTime = PR_Now() / 1000;
-    // TODO: If we can know scan code of the key event which caused replacing
-    //       composition string, we should set mCodeNameIndex here.  Then,
-    //       we should rename this method because it becomes not a "dummy"
-    //       keyboard event.
-    event.mKeyCode = NS_VK_PROCESSKEY;
-    event.mKeyNameIndex = KEY_NAME_INDEX_Process;
+    MOZ_ASSERT(event.mKeyCode == 0);
     NS_ENSURE_SUCCESS_VOID(BeginInputTransaction(mDispatcher));
     mDispatcher->DispatchKeyboardEvent(msg, event, status);
 }
@@ -1031,19 +1027,12 @@ GeckoEditableSupport::OnImeReplaceText(int32_t aStart, int32_t aEnd,
         AddIMETextChange(dummyChange);
     }
 
-    // Until fixing bug 354358 in release channel, we should always ignore
-    // "intl.ime.hack.on_ime_unaware_apps.fire_key_events_for_composition"
-    // pref in Nightly and early Beta for testing new regressions.
-#ifndef EARLY_BETA_OR_EARLIER
     if (mInputContext.mMayBeIMEUnaware) {
-#endif // #ifndef EARLY_BETA_OR_EARLIER
         SendIMEDummyKeyEvent(widget, eKeyDown);
         if (!mDispatcher || widget->Destroyed()) {
             return;
         }
-#ifndef EARLY_BETA_OR_EARLIER
     }
-#endif // #ifndef EARLY_BETA_OR_EARLIER
 
     if (composing) {
         mDispatcher->SetPendingComposition(string, mIMERanges);
@@ -1057,18 +1046,10 @@ GeckoEditableSupport::OnImeReplaceText(int32_t aStart, int32_t aEnd,
         return;
     }
 
-    // XXX This works fine if user inputs with virtual keyboard.  However,
-    //     if user inputs with hardware keyboard, keyup event may come later.
-    //     So, perhaps, we need to record actual keyboard events before
-    //     this replacement of composition string.
-#ifndef EARLY_BETA_OR_EARLIER
     if (mInputContext.mMayBeIMEUnaware) {
-#endif // #ifndef EARLY_BETA_OR_EARLIER
         SendIMEDummyKeyEvent(widget, eKeyUp);
         // Widget may be destroyed after dispatching the above event.
-#ifndef EARLY_BETA_OR_EARLIER
     }
-#endif // #ifndef EARLY_BETA_OR_EARLIER
 }
 
 void
diff --git a/widget/cocoa/TextInputHandler.h b/widget/cocoa/TextInputHandler.h
index 74e8fec9c581..1e41c3752822 100644
--- a/widget/cocoa/TextInputHandler.h
+++ b/widget/cocoa/TextInputHandler.h
@@ -243,9 +243,6 @@ public:
    *                              dispatch a Gecko key event.
    * @param aKeyEvent             The result -- a Gecko key event initialized
    *                              from the native key event.
-   * @param aIsProcessedByIME     true if aNativeKeyEvent has been handled
-   *                              by IME (but except if the composition was
-   *                              started with dead key).
    * @param aInsertString         If caller expects that the event will cause
    *                              a character to be input (say in an editor),
    *                              the caller should set this.  Otherwise,
@@ -254,7 +251,6 @@ public:
    *                              characters of aNativeKeyEvent.
    */
   void InitKeyEvent(NSEvent *aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
-                    bool aIsProcessedByIME,
                     const nsAString *aInsertString = nullptr);
 
   /**
@@ -307,15 +303,6 @@ public:
   static CodeNameIndex ComputeGeckoCodeNameIndex(UInt32 aNativeKeyCode,
                                                  UInt32 aKbType);
 
-  /**
-   * TranslateToChar() checks if aNativeKeyEvent is a dead key.
-   *
-   * @param aNativeKeyEvent       A native key event.
-   * @return                      Returns true if the key event is a dead key
-   *                              event.  Otherwise, false.
-   */
-  bool IsDeadKey(NSEvent* aNativeKeyEvent);
-
 protected:
   /**
    * TranslateToString() computes the inputted text from the native keyCode,
@@ -356,7 +343,7 @@ protected:
    * @param aKbType               A native Keyboard Type value.  Typically,
    *                              this is a result of ::LMGetKbdType().
    * @return                      Returns true if the key with specified
-   *                              modifier state is a dead key.  Otherwise,
+   *                              modifier state isa dead key.  Otherwise,
    *                              false.
    */
   bool IsDeadKey(UInt32 aKeyCode, UInt32 aModifiers, UInt32 aKbType);
@@ -446,9 +433,6 @@ public:
    *                              dispatch a Gecko key event.
    * @param aKeyEvent             The result -- a Gecko key event initialized
    *                              from the native key event.
-   * @param aIsProcessedByIME     true if aNativeKeyEvent has been handled
-   *                              by IME (but except if the composition was
-   *                              started with dead key).
    * @param aInsertString         If caller expects that the event will cause
    *                              a character to be input (say in an editor),
    *                              the caller should set this.  Otherwise,
@@ -457,7 +441,6 @@ public:
    *                              characters of aNativeKeyEvent.
    */
   void InitKeyEvent(NSEvent *aNativeKeyEvent, WidgetKeyboardEvent& aKeyEvent,
-                    bool aIsProcessedByIME,
                     const nsAString *aInsertString = nullptr);
 
   /**
@@ -569,8 +552,6 @@ protected:
     // Unique id associated with a keydown / keypress event. It's ok if this
     // wraps over long periods.
     uint32_t mUniqueId;
-    // Whether keydown event was dispatched for mKeyEvent.
-    bool mKeyDownDispatched;
     // Whether keydown event was consumed by web contents or chrome contents.
     bool mKeyDownHandled;
     // Whether keypress event was dispatched for mKeyEvent.
@@ -623,7 +604,6 @@ protected:
       }
       mInsertString = nullptr;
       mInsertedString.Truncate();
-      mKeyDownDispatched = false;
       mKeyDownHandled = false;
       mKeyPressDispatched = false;
       mKeyPressHandled = false;
@@ -637,11 +617,6 @@ protected:
              mCompositionDispatched;
     }
 
-    bool CanDispatchKeyDownEvent() const
-    {
-      return !mKeyDownDispatched;
-    }
-
     bool CanDispatchKeyPressEvent() const
     {
       return !mKeyPressDispatched && !IsDefaultPrevented();
@@ -790,8 +765,7 @@ protected:
     }
 
     void InitKeyEvent(TextInputHandlerBase* aHandler,
-                      WidgetKeyboardEvent& aKeyEvent,
-                      bool aIsProcessedByIME);
+                      WidgetKeyboardEvent& aKeyEvent);
 
     /**
      * GetUnhandledString() returns characters of the event which have not been
@@ -1085,7 +1059,6 @@ public:
   NSRange MarkedRange();
 
   bool IsIMEComposing() { return mIsIMEComposing; }
-  bool IsDeadKeyComposing() { return mIsDeadKeyComposing; }
   bool IsIMEOpened();
   bool IsIMEEnabled() { return mIsIMEEnabled; }
   bool IsASCIICapableOnly() { return mIsASCIICapableOnly; }
@@ -1139,19 +1112,6 @@ protected:
   void InsertTextAsCommittingComposition(NSAttributedString* aAttrString,
                                          NSRange* aReplacementRange);
 
-  /**
-   * MaybeDispatchCurrentKeydownEvent() dispatches eKeyDown event for current
-   * key event.  If eKeyDown for current key event has already been dispatched,
-   * this does nothing.
-   *
-   * @param aIsProcessedByIME   true if current key event is handled by IME.
-   * @return                    true if the caller can continue to handle
-   *                            current key event.  Otherwise, false.  E.g.,
-   *                            focus is moved, the widget has been destroyed
-   *                            or something.
-   */
-  bool MaybeDispatchCurrentKeydownEvent(bool aIsProcessedByIME);
-
 private:
   // If mIsIMEComposing is true, the composition string is stored here.
   NSString* mIMECompositionString;
@@ -1165,9 +1125,6 @@ private:
   mozilla::WritingMode mWritingMode;
 
   bool mIsIMEComposing;
-  // If the composition started with dead key, mIsDeadKeyComposing is set to
-  // true.
-  bool mIsDeadKeyComposing;
   bool mIsIMEEnabled;
   bool mIsASCIICapableOnly;
   bool mIgnoreIMECommit;
diff --git a/widget/cocoa/TextInputHandler.mm b/widget/cocoa/TextInputHandler.mm
index eb2057a85a08..106ef0e91f52 100644
--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -399,84 +399,6 @@ TISInputSourceWrapper::TranslateToChar(UInt32 aKeyCode, UInt32 aModifiers,
   return static_cast<uint32_t>(str.CharAt(0));
 }
 
-bool
-TISInputSourceWrapper::IsDeadKey(NSEvent* aNativeKeyEvent)
-{
-  if ([[aNativeKeyEvent characters] length]) {
-    return false;
-  }
-
-  // Assmue that if control key or command key is pressed, it's not a dead key.
-  NSUInteger cocoaState = [aNativeKeyEvent modifierFlags];
-  if (cocoaState & (NSControlKeyMask | NSCommandKeyMask)) {
-    return false;
-  }
-
-  UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
-  switch (nativeKeyCode) {
-    case kVK_ANSI_A:
-    case kVK_ANSI_B:
-    case kVK_ANSI_C:
-    case kVK_ANSI_D:
-    case kVK_ANSI_E:
-    case kVK_ANSI_F:
-    case kVK_ANSI_G:
-    case kVK_ANSI_H:
-    case kVK_ANSI_I:
-    case kVK_ANSI_J:
-    case kVK_ANSI_K:
-    case kVK_ANSI_L:
-    case kVK_ANSI_M:
-    case kVK_ANSI_N:
-    case kVK_ANSI_O:
-    case kVK_ANSI_P:
-    case kVK_ANSI_Q:
-    case kVK_ANSI_R:
-    case kVK_ANSI_S:
-    case kVK_ANSI_T:
-    case kVK_ANSI_U:
-    case kVK_ANSI_V:
-    case kVK_ANSI_W:
-    case kVK_ANSI_X:
-    case kVK_ANSI_Y:
-    case kVK_ANSI_Z:
-    case kVK_ANSI_1:
-    case kVK_ANSI_2:
-    case kVK_ANSI_3:
-    case kVK_ANSI_4:
-    case kVK_ANSI_5:
-    case kVK_ANSI_6:
-    case kVK_ANSI_7:
-    case kVK_ANSI_8:
-    case kVK_ANSI_9:
-    case kVK_ANSI_0:
-    case kVK_ANSI_Equal:
-    case kVK_ANSI_Minus:
-    case kVK_ANSI_RightBracket:
-    case kVK_ANSI_LeftBracket:
-    case kVK_ANSI_Quote:
-    case kVK_ANSI_Semicolon:
-    case kVK_ANSI_Backslash:
-    case kVK_ANSI_Comma:
-    case kVK_ANSI_Slash:
-    case kVK_ANSI_Period:
-    case kVK_ANSI_Grave:
-    case kVK_JIS_Yen:
-    case kVK_JIS_Underscore:
-      break;
-    default:
-      // Let's assume that dead key can be only a printable key in standard
-      // position.
-      return false;
-  }
-
-  // If TranslateToChar() returns non-zero value, that means that
-  // the key may input a character with different dead key state.
-  UInt32 kbType = GetKbdType();
-  UInt32 carbonState = nsCocoaUtils::ConvertToCarbonModifier(cocoaState);
-  return IsDeadKey(nativeKeyCode, carbonState, kbType);
-}
-
 bool
 TISInputSourceWrapper::IsDeadKey(UInt32 aKeyCode,
                                  UInt32 aModifiers,
@@ -984,25 +906,17 @@ TISInputSourceWrapper::ComputeInsertStringForCharCode(
 void
 TISInputSourceWrapper::InitKeyEvent(NSEvent *aNativeKeyEvent,
                                     WidgetKeyboardEvent& aKeyEvent,
-                                    bool aIsProcessedByIME,
                                     const nsAString *aInsertString)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
-  MOZ_ASSERT(!aIsProcessedByIME || aKeyEvent.mMessage != eKeyPress,
-    "eKeyPress event should not be marked as proccessed by IME");
-
   MOZ_LOG(gLog, LogLevel::Info,
     ("%p TISInputSourceWrapper::InitKeyEvent, aNativeKeyEvent=%p, "
-     "aKeyEvent.mMessage=%s, aProcessedByIME=%s, aInsertString=%p, "
-     "IsOpenedIMEMode()=%s",
-     this, aNativeKeyEvent, GetGeckoKeyEventType(aKeyEvent),
-     TrueOrFalse(aIsProcessedByIME), aInsertString,
+     "aKeyEvent.mMessage=%s, aInsertString=%p, IsOpenedIMEMode()=%s",
+     this, aNativeKeyEvent, GetGeckoKeyEventType(aKeyEvent), aInsertString,
      TrueOrFalse(IsOpenedIMEMode())));
 
-  if (NS_WARN_IF(!aNativeKeyEvent)) {
-    return;
-  }
+  NS_ENSURE_TRUE(aNativeKeyEvent, );
 
   nsCocoaUtils::InitInputEvent(aKeyEvent, aNativeKeyEvent);
 
@@ -1031,18 +945,8 @@ TISInputSourceWrapper::InitKeyEvent(NSEvent *aNativeKeyEvent,
   UInt32 kbType = GetKbdType();
   UInt32 nativeKeyCode = [aNativeKeyEvent keyCode];
 
-  // macOS handles dead key as IME.  If the key is first key press of dead
-  // key, we should use KEY_NAME_INDEX_Dead for first (dead) key event.
-  // So, if aIsProcessedByIME is true, it may be dead key.  Let's check
-  // if current key event is a dead key's keydown event.
-  bool isProcessedByIME =
-    aIsProcessedByIME &&
-    !TISInputSourceWrapper::CurrentInputSource().IsDeadKey(aNativeKeyEvent);
-
   aKeyEvent.mKeyCode =
-    isProcessedByIME ?
-      NS_VK_PROCESSKEY :
-      ComputeGeckoKeyCode(nativeKeyCode, kbType, aKeyEvent.IsMeta());
+    ComputeGeckoKeyCode(nativeKeyCode, kbType, aKeyEvent.IsMeta());
 
   switch (nativeKeyCode) {
     case kVK_Command:
@@ -1095,9 +999,7 @@ TISInputSourceWrapper::InitKeyEvent(NSEvent *aNativeKeyEvent,
      this, OnOrOff(aKeyEvent.IsShift()), OnOrOff(aKeyEvent.IsControl()),
      OnOrOff(aKeyEvent.IsAlt()), OnOrOff(aKeyEvent.IsMeta())));
 
-  if (isProcessedByIME) {
-    aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_Process;
-  } else if (IsPrintableKeyEvent(aNativeKeyEvent)) {
+  if (IsPrintableKeyEvent(aNativeKeyEvent)) {
     aKeyEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
     // If insertText calls this method, let's use the string.
     if (aInsertString && !aInsertString->IsEmpty() &&
@@ -1726,7 +1628,7 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
       }
 
       WidgetKeyboardEvent imeEvent(true, eKeyDown, widget);
-      currentKeyEvent->InitKeyEvent(this, imeEvent, false);
+      currentKeyEvent->InitKeyEvent(this, imeEvent);
       imeEvent.mPluginTextEventString.Assign(committed);
       nsEventStatus status = nsEventStatus_eIgnore;
       mDispatcher->DispatchKeyboardEvent(eKeyDown, imeEvent, status,
@@ -1735,18 +1637,50 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
     return true;
   }
 
-  RefPtr<TextInputHandler> kungFuDeathGrip(this);
+  NSResponder* firstResponder = [[mView window] firstResponder];
 
-  // When we're already in a composition, we need always to mark the eKeyDown
-  // event as "processed by IME".  So, let's dispatch eKeyDown event here in
-  // such case.
-  if (IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(true)) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::HandleKeyDownEvent, eKeyDown caused focus move or "
-       "something and canceling the composition", this));
+  nsresult rv = mDispatcher->BeginNativeInputTransaction();
+  if (NS_WARN_IF(NS_FAILED(rv))) {
+      MOZ_LOG(gLog, LogLevel::Error,
+        ("%p IMEInputHandler::HandleKeyDownEvent, "
+         "FAILED, due to BeginNativeInputTransaction() failure "
+         "at dispatching keydown for ordinal cases", this));
     return false;
   }
 
+  WidgetKeyboardEvent keydownEvent(true, eKeyDown, widget);
+  currentKeyEvent->InitKeyEvent(this, keydownEvent);
+
+  nsEventStatus status = nsEventStatus_eIgnore;
+  mDispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent, status,
+                                     currentKeyEvent);
+  currentKeyEvent->mKeyDownHandled =
+    (status == nsEventStatus_eConsumeNoDefault);
+
+  if (Destroyed()) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p TextInputHandler::HandleKeyDownEvent, "
+       "widget was destroyed by keydown event", this));
+    return currentKeyEvent->IsDefaultPrevented();
+  }
+
+  // The key down event may have shifted the focus, in which
+  // case we should not fire the key press.
+  // XXX This is a special code only on Cocoa widget, why is this needed?
+  if (firstResponder != [[mView window] firstResponder]) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p TextInputHandler::HandleKeyDownEvent, "
+       "view lost focus by keydown event", this));
+    return currentKeyEvent->IsDefaultPrevented();
+  }
+
+  if (currentKeyEvent->IsDefaultPrevented()) {
+    MOZ_LOG(gLog, LogLevel::Info,
+      ("%p TextInputHandler::HandleKeyDownEvent, "
+       "keydown event's default is prevented", this));
+    return true;
+  }
+
   // Let Cocoa interpret the key events, caching IsIMEComposing first.
   bool wasComposing = IsIMEComposing();
   bool interpretKeyEventsCalled = false;
@@ -1776,33 +1710,9 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
      "IsIMEComposing()=%s",
      this, TrueOrFalse(wasComposing), TrueOrFalse(IsIMEComposing())));
 
-  if (currentKeyEvent->CanDispatchKeyDownEvent()) {
-    // Dispatch eKeyDown event if nobody has dispatched it yet.
-    // NOTE: Although reaching here means that the native keydown event may
-    //       not be handled by IME.  However, we cannot know if it is.
-    //       For example, Japanese IME of Apple shows candidate window for
-    //       typing window.  They, you can switch the sort order with Tab key.
-    //       However, when you choose "Symbol" of the sort order, there may
-    //       be no candiate words.  In this case, IME handles the Tab key
-    //       actually, but we cannot know it because composition string is
-    //       not updated.  So, let's mark eKeyDown event as "processed by IME"
-    //       when there is composition string.  This is same as Chrome.
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p TextInputHandler::HandleKeyDownEvent, trying to dispatch eKeyDown "
-       "event since it's not yet dispatched",
-       this));
-    if (!MaybeDispatchCurrentKeydownEvent(IsIMEComposing())) {
-      return true; // treat the eKeydDown event as consumed.
-    }
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p TextInputHandler::HandleKeyDownEvent, eKeyDown event has been "
-       "dispatched",
-       this));
-  }
-
   if (currentKeyEvent->CanDispatchKeyPressEvent() &&
       !wasComposing && !IsIMEComposing()) {
-    nsresult rv = mDispatcher->BeginNativeInputTransaction();
+    rv = mDispatcher->BeginNativeInputTransaction();
     if (NS_WARN_IF(NS_FAILED(rv))) {
         MOZ_LOG(gLog, LogLevel::Error,
           ("%p IMEInputHandler::HandleKeyDownEvent, "
@@ -1812,7 +1722,7 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
     }
 
     WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
-    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent);
 
     // If we called interpretKeyEvents and this isn't normal character input
     // then IME probably ate the event for some reason. We do not want to
@@ -1827,11 +1737,6 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
     //    our default action for this key.
     if (!(interpretKeyEventsCalled &&
           IsNormalCharInputtingEvent(keypressEvent))) {
-      MOZ_LOG(gLog, LogLevel::Info,
-        ("%p TextInputHandler::HandleKeyDownEvent, trying to dispatch "
-         "eKeyPress event since it's not yet dispatched",
-         this));
-      nsEventStatus status = nsEventStatus_eIgnore;
       currentKeyEvent->mKeyPressDispatched =
         mDispatcher->MaybeDispatchKeypressEvents(keypressEvent, status,
                                                  currentKeyEvent);
@@ -1839,8 +1744,7 @@ TextInputHandler::HandleKeyDownEvent(NSEvent* aNativeEvent,
         (status == nsEventStatus_eConsumeNoDefault);
       currentKeyEvent->mKeyPressDispatched = true;
       MOZ_LOG(gLog, LogLevel::Info,
-        ("%p TextInputHandler::HandleKeyDownEvent, eKeyPress event has been "
-         "dispatched",
+        ("%p TextInputHandler::HandleKeyDownEvent, keypress event dispatched",
          this));
     }
   }
@@ -1894,10 +1798,8 @@ TextInputHandler::HandleKeyUpEvent(NSEvent* aNativeEvent)
     return;
   }
 
-  // Neither Chrome for macOS nor Safari marks "keyup" event as "processed by
-  // IME" even during composition.  So, let's follow this behavior.
   WidgetKeyboardEvent keyupEvent(true, eKeyUp, mWidget);
-  InitKeyEvent(aNativeEvent, keyupEvent, false);
+  InitKeyEvent(aNativeEvent, keyupEvent);
 
   KeyEventState currentKeyEvent(aNativeEvent);
   nsEventStatus status = nsEventStatus_eIgnore;
@@ -2241,7 +2143,7 @@ TextInputHandler::DispatchKeyEventForFlagsChanged(NSEvent* aNativeEvent,
      GetKeyNameForNativeKeyCode([aNativeEvent keyCode]), [aNativeEvent keyCode],
      TrueOrFalse(aDispatchKeyDown), TrueOrFalse(IsIMEComposing())));
 
-  if ([aNativeEvent type] != NSFlagsChanged) {
+  if ([aNativeEvent type] != NSFlagsChanged || IsIMEComposing()) {
     return;
   }
 
@@ -2255,11 +2157,9 @@ TextInputHandler::DispatchKeyEventForFlagsChanged(NSEvent* aNativeEvent,
 
   EventMessage message = aDispatchKeyDown ? eKeyDown : eKeyUp;
 
-  // Fire a key event for the modifier key.  Note that even if modifier key
-  // is pressed during composition, we shouldn't mark the keyboard event as
-  // "processed by IME" since neither Chrome for macOS nor Safari does it.
+  // Fire a key event.
   WidgetKeyboardEvent keyEvent(true, message, mWidget);
-  InitKeyEvent(aNativeEvent, keyEvent, false);
+  InitKeyEvent(aNativeEvent, keyEvent);
 
   // Attach a plugin event, in case keyEvent gets dispatched to a plugin.  Only
   // one field is needed -- the type.  The other fields can be constructed as
@@ -2295,16 +2195,13 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
     ("%p TextInputHandler::InsertText, aAttrString=\"%s\", "
      "aReplacementRange=%p { location=%lu, length=%lu }, "
      "IsIMEComposing()=%s, "
-     "keyevent=%p, keydownDispatched=%s, "
-     "keydownHandled=%s, keypressDispatched=%s, "
+     "keyevent=%p, keydownHandled=%s, keypressDispatched=%s, "
      "causedOtherKeyEvents=%s, compositionDispatched=%s",
      this, GetCharacters([aAttrString string]), aReplacementRange,
      static_cast<unsigned long>(aReplacementRange ? aReplacementRange->location : 0),
      static_cast<unsigned long>(aReplacementRange ? aReplacementRange->length : 0),
      TrueOrFalse(IsIMEComposing()),
      currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
-     currentKeyEvent ?
-       TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
      currentKeyEvent ?
@@ -2356,21 +2253,8 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
     if (!currentKeyEvent) {
       return;
     }
-
-    // When current keydown event causes this empty text input, let's
-    // dispatch eKeyDown event before any other events.  Note that if we're
-    // in a composition, we've already dispatched eKeyDown event from
-    // TextInputHandler::HandleKeyDownEvent().
-    // XXX Should we mark this eKeyDown event as "processed by IME"?
-    RefPtr<TextInputHandler> kungFuDeathGrip(this);
-    if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
-      MOZ_LOG(gLog, LogLevel::Info,
-        ("%p IMEInputHandler::InsertText, eKeyDown caused focus move or "
-         "something and canceling the composition", this));
-      return;
-    }
-
     // Delete the selected range.
+    RefPtr<TextInputHandler> kungFuDeathGrip(this);
     WidgetContentCommandEvent deleteCommandEvent(true, eContentCommandDelete,
                                                  mWidget);
     DispatchEvent(deleteCommandEvent);
@@ -2419,23 +2303,13 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
     return;
   }
 
-  // This is the normal path to input a character when you press a key.
-  // Let's dispatch eKeyDown event now.
-  RefPtr<TextInputHandler> kungFuDeathGrip(this);
-  if (!MaybeDispatchCurrentKeydownEvent(false)) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::InsertText, eKeyDown caused focus move or "
-       "something and canceling the composition", this));
-    return;
-  }
-
   // XXX Shouldn't we hold mDispatcher instead of mWidget?
   RefPtr<nsChildView> widget(mWidget);
   nsresult rv = mDispatcher->BeginNativeInputTransaction();
   if (NS_WARN_IF(NS_FAILED(rv))) {
-    MOZ_LOG(gLog, LogLevel::Error,
-      ("%p IMEInputHandler::InsertText, "
-       "FAILED, due to BeginNativeInputTransaction() failure", this));
+      MOZ_LOG(gLog, LogLevel::Error,
+        ("%p IMEInputHandler::HandleKeyUpEvent, "
+         "FAILED, due to BeginNativeInputTransaction() failure", this));
     return;
   }
 
@@ -2451,7 +2325,7 @@ TextInputHandler::InsertText(NSAttributedString* aAttrString,
   // the input string.
 
   if (currentKeyEvent) {
-    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent);
   } else {
     nsCocoaUtils::InitInputEvent(keypressEvent, static_cast<NSEvent*>(nullptr));
     keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
@@ -2517,18 +2391,6 @@ TextInputHandler::HandleCommand(Command aCommand)
     return false;
   }
 
-  // When current keydown event causes this command, let's dispatch
-  // eKeyDown event before any other events.  Note that if we're in a
-  // composition, we've already dispatched eKeyDown event from
-  // TextInputHandler::HandleKeyDownEvent().
-  RefPtr<TextInputHandler> kungFuDeathGrip(this);
-  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
-       "something and canceling the composition", this));
-    return false;
-  }
-
   // If it's in composition, we cannot dispatch keypress event.
   // Therefore, we should use different approach or give up to handle
   // the command.
@@ -2625,7 +2487,7 @@ TextInputHandler::HandleCommand(Command aCommand)
   if (!dispatchFakeKeyPress) {
     // If we're acutally handling a key press, we should dispatch
     // the keypress event as-is.
-    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent);
   } else {
     // Otherwise, we should dispatch "fake" keypress event.
     // However, for making it possible to compute edit commands, we need to
@@ -2891,15 +2753,11 @@ TextInputHandler::DoCommandBySelector(const char* aSelector)
 
   MOZ_LOG(gLog, LogLevel::Info,
     ("%p TextInputHandler::DoCommandBySelector, aSelector=\"%s\", "
-     "Destroyed()=%s, keydownDispatched=%s, keydownHandled=%s, "
-     "keypressDispatched=%s, keypressHandled=%s, causedOtherKeyEvents=%s",
+     "Destroyed()=%s, keydownHandled=%s, keypressHandled=%s, "
+     "causedOtherKeyEvents=%s",
      this, aSelector ? aSelector : "", TrueOrFalse(Destroyed()),
-     currentKeyEvent ?
-       TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
-     currentKeyEvent ?
-       TrueOrFalse(currentKeyEvent->mKeyPressDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyPressHandled) : "N/A",
      currentKeyEvent ?
@@ -2911,18 +2769,6 @@ TextInputHandler::DoCommandBySelector(const char* aSelector)
     return Destroyed();
   }
 
-  // When current keydown event causes this command, let's dispatch
-  // eKeyDown event before any other events.  Note that if we're in a
-  // composition, we've already dispatched eKeyDown event from
-  // TextInputHandler::HandleKeyDownEvent().
-  RefPtr<TextInputHandler> kungFuDeathGrip(this);
-  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
-       "something and canceling the composition", this));
-    return true;
-  }
-
   // If the key operation causes this command, should dispatch a keypress
   // event.
   // XXX This must be worng.  Even if this command is caused by the key
@@ -2940,7 +2786,7 @@ TextInputHandler::DoCommandBySelector(const char* aSelector)
     }
 
     WidgetKeyboardEvent keypressEvent(true, eKeyPress, widget);
-    currentKeyEvent->InitKeyEvent(this, keypressEvent, false);
+    currentKeyEvent->InitKeyEvent(this, keypressEvent);
 
     nsEventStatus status = nsEventStatus_eIgnore;
     currentKeyEvent->mKeyPressDispatched =
@@ -3553,11 +3399,6 @@ IMEInputHandler::DispatchCompositionStartEvent()
 
   NS_ASSERTION(!mIsIMEComposing, "There is a composition already");
   mIsIMEComposing = true;
-  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
-  mIsDeadKeyComposing =
-     currentKeyEvent && currentKeyEvent->mKeyEvent &&
-     TISInputSourceWrapper::CurrentInputSource().
-                              IsDeadKey(currentKeyEvent->mKeyEvent);
 
   nsEventStatus status;
   rv = mDispatcher->StartComposition(status);
@@ -3708,7 +3549,7 @@ IMEInputHandler::DispatchCompositionCommitEvent(const nsAString* aCommitString)
     }
   }
 
-  mIsIMEComposing = mIsDeadKeyComposing = false;
+  mIsIMEComposing = false;
   mIMECompositionStart = UINT32_MAX;
   if (mIMECompositionString) {
     [mIMECompositionString release];
@@ -3727,89 +3568,6 @@ IMEInputHandler::DispatchCompositionCommitEvent(const nsAString* aCommitString)
   NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(false);
 }
 
-bool
-IMEInputHandler::MaybeDispatchCurrentKeydownEvent(bool aIsProcessedByIME)
-{
-  NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
-
-  if (Destroyed()) {
-    return false;
-  }
-  MOZ_ASSERT(mWidget);
-
-  KeyEventState* currentKeyEvent = GetCurrentKeyEvent();
-  if (!currentKeyEvent ||
-      !currentKeyEvent->CanDispatchKeyDownEvent()) {
-    return true;
-  }
-
-  NSEvent* nativeEvent = currentKeyEvent->mKeyEvent;
-  if (NS_WARN_IF(!nativeEvent) ||
-      [nativeEvent type] != NSKeyDown) {
-    return true;
-  }
-
-  MOZ_LOG(gLog, LogLevel::Info,
-    ("%p IMEInputHandler::MaybeDispatchKeydownEvent, aIsProcessedByIME=%s "
-     "currentKeyEvent={ mKeyEvent(%p)={ type=%s, keyCode=%s (0x%X) } }, "
-     "aIsProcesedBy=%s, IsDeadKeyComposing()=%s",
-     this, TrueOrFalse(aIsProcessedByIME), nativeEvent,
-     GetNativeKeyEventType(nativeEvent),
-     GetKeyNameForNativeKeyCode([nativeEvent keyCode]), [nativeEvent keyCode],
-     TrueOrFalse(IsIMEComposing()), TrueOrFalse(IsDeadKeyComposing())));
-
-  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
-  RefPtr<TextEventDispatcher> dispatcher(mDispatcher);
-  nsresult rv = dispatcher->BeginNativeInputTransaction();
-  if (NS_WARN_IF(NS_FAILED(rv))) {
-      MOZ_LOG(gLog, LogLevel::Error,
-        ("%p IMEInputHandler::DispatchKeyEventForFlagsChanged, "
-         "FAILED, due to BeginNativeInputTransaction() failure", this));
-    return false;
-  }
-
-  NSResponder* firstResponder = [[mView window] firstResponder];
-
-  // Mark currentKeyEvent as "dispatched eKeyDown event" and actually do it.
-  currentKeyEvent->mKeyDownDispatched = true;
-
-  RefPtr<nsChildView> widget(mWidget);
-
-  WidgetKeyboardEvent keydownEvent(true, eKeyDown, widget);
-  // Don't mark the eKeyDown event as "processed by IME" if the composition
-  // is started with dead key.
-  currentKeyEvent->InitKeyEvent(this, keydownEvent,
-                                aIsProcessedByIME && !IsDeadKeyComposing());
-
-  nsEventStatus status = nsEventStatus_eIgnore;
-  dispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent, status,
-                                    currentKeyEvent);
-  currentKeyEvent->mKeyDownHandled =
-    (status == nsEventStatus_eConsumeNoDefault);
-
-  if (Destroyed()) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::MaybeDispatchKeydownEvent, "
-       "widget was destroyed by keydown event", this));
-    return false;
-  }
-
-  // The key down event may have shifted the focus, in which case, we should
-  // not continue to handle current key sequence and let's commit current
-  // composition.
-  if (firstResponder != [[mView window] firstResponder]) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::MaybeDispatchKeydownEvent, "
-       "view lost focus by keydown event", this));
-    CommitIMEComposition();
-    return false;
-  }
-
-  return true;
-
-  NS_OBJC_END_TRY_ABORT_BLOCK_RETURN(false);
-}
-
 void
 IMEInputHandler::InsertTextAsCommittingComposition(
                    NSAttributedString* aAttrString,
@@ -3838,22 +3596,6 @@ IMEInputHandler::InsertTextAsCommittingComposition(
     return;
   }
 
-  // When current keydown event causes this text input, let's dispatch
-  // eKeyDown event before any other events.  Note that if we're in a
-  // composition, we've already dispatched eKeyDown event from
-  // TextInputHandler::HandleKeyDownEvent().
-  // XXX Should we mark the eKeyDown event as "processed by IME"?
-  //     However, if the key causes two or more Unicode characters as
-  //     UTF-16 string, this is used.  So, perhaps, we need to improve
-  //     HandleKeyDownEvent() before do that.
-  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
-  if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(false)) {
-    MOZ_LOG(gLog, LogLevel::Info,
-      ("%p IMEInputHandler::InsertTextAsCommittingComposition, eKeyDown "
-       "caused focus move or something and canceling the composition", this));
-    return;
-  }
-
   // First, commit current composition with the latest composition string if the
   // replacement range is different from marked range.
   if (IsIMEComposing() && aReplacementRange &&
@@ -3868,6 +3610,8 @@ IMEInputHandler::InsertTextAsCommittingComposition(
     }
   }
 
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
   nsString str;
   nsCocoaUtils::GetStringForNSString([aAttrString string], str);
 
@@ -3914,8 +3658,7 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
      "aReplacementRange=%p { location=%lu, length=%lu }, "
      "Destroyed()=%s, IsIMEComposing()=%s, "
      "mMarkedRange={ location=%lu, length=%lu }, keyevent=%p, "
-     "keydownDispatched=%s, keydownHandled=%s, "
-     "keypressDispatched=%s, causedOtherKeyEvents=%s, "
+     "keydownHandled=%s, keypressDispatched=%s, causedOtherKeyEvents=%s, "
      "compositionDispatched=%s",
      this, GetCharacters([aAttrString string]),
      static_cast<unsigned long>(aSelectedRange.location),
@@ -3926,8 +3669,6 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
      static_cast<unsigned long>(mMarkedRange.location),
      static_cast<unsigned long>(mMarkedRange.length),
      currentKeyEvent ? currentKeyEvent->mKeyEvent : nullptr,
-     currentKeyEvent ?
-       TrueOrFalse(currentKeyEvent->mKeyDownDispatched) : "N/A",
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mKeyDownHandled) : "N/A",
      currentKeyEvent ?
@@ -3937,32 +3678,19 @@ IMEInputHandler::SetMarkedText(NSAttributedString* aAttrString,
      currentKeyEvent ?
        TrueOrFalse(currentKeyEvent->mCompositionDispatched) : "N/A"));
 
-  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
-
   // If SetMarkedText() is called during handling a key press, that means that
   // the key event caused this composition.  So, keypress event shouldn't
   // be dispatched later, let's mark the key event causing composition event.
   if (currentKeyEvent) {
     currentKeyEvent->mCompositionDispatched = true;
-
-    // When current keydown event causes this text input, let's dispatch
-    // eKeyDown event before any other events.  Note that if we're in a
-    // composition, we've already dispatched eKeyDown event from
-    // TextInputHandler::HandleKeyDownEvent().  On the other hand, if we're
-    // not in composition, the key event starts new composition.  So, we
-    // need to mark the eKeyDown event as "processed by IME".
-    if (!IsIMEComposing() && !MaybeDispatchCurrentKeydownEvent(true)) {
-      MOZ_LOG(gLog, LogLevel::Info,
-        ("%p IMEInputHandler::SetMarkedText, eKeyDown caused focus move or "
-         "something and canceling the composition", this));
-      return;
-    }
   }
 
   if (Destroyed()) {
     return;
   }
 
+  RefPtr<IMEInputHandler> kungFuDeathGrip(this);
+
   // First, commit current composition with the latest composition string if the
   // replacement range is different from marked range.
   if (IsIMEComposing() && aReplacementRange &&
@@ -4419,7 +4147,6 @@ IMEInputHandler::IMEInputHandler(nsChildView* aWidget,
   , mIMECompositionString(nullptr)
   , mIMECompositionStart(UINT32_MAX)
   , mIsIMEComposing(false)
-  , mIsDeadKeyComposing(false)
   , mIsIMEEnabled(true)
   , mIsASCIICapableOnly(false)
   , mIgnoreIMECommit(false)
@@ -4578,15 +4305,13 @@ IMEInputHandler::CommitIMEComposition()
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
+  if (!IsIMEComposing())
+    return;
+
   MOZ_LOG(gLog, LogLevel::Info,
     ("%p IMEInputHandler::CommitIMEComposition, mIMECompositionString=%s",
      this, GetCharacters(mIMECompositionString)));
 
-  // If this is called before dispatching eCompositionStart, IsIMEComposing()
-  // returns false.  Even in such case, we need to commit composition *in*
-  // IME if this is called by preceding eKeyDown event of eCompositionStart.
-  // So, we need to call KillIMEComposition() even when IsIMEComposing()
-  // returns false.
   KillIMEComposition();
 
   if (!IsIMEComposing())
@@ -4860,7 +4585,6 @@ TextInputHandlerBase::DispatchEvent(WidgetGUIEvent& aEvent)
 void
 TextInputHandlerBase::InitKeyEvent(NSEvent *aNativeKeyEvent,
                                    WidgetKeyboardEvent& aKeyEvent,
-                                   bool aIsProcessedByIME,
                                    const nsAString* aInsertString)
 {
   NS_ASSERTION(aNativeKeyEvent, "aNativeKeyEvent must not be NULL");
@@ -4868,12 +4592,11 @@ TextInputHandlerBase::InitKeyEvent(NSEvent *aNativeKeyEvent,
   if (mKeyboardOverride.mOverrideEnabled) {
     TISInputSourceWrapper tis;
     tis.InitByLayoutID(mKeyboardOverride.mKeyboardLayout, true);
-    tis.InitKeyEvent(aNativeKeyEvent, aKeyEvent, aIsProcessedByIME,
-                     aInsertString);
+    tis.InitKeyEvent(aNativeKeyEvent, aKeyEvent, aInsertString);
     return;
   }
   TISInputSourceWrapper::CurrentInputSource().
-    InitKeyEvent(aNativeKeyEvent, aKeyEvent, aIsProcessedByIME, aInsertString);
+    InitKeyEvent(aNativeKeyEvent, aKeyEvent, aInsertString);
 }
 
 nsresult
@@ -5166,8 +4889,7 @@ TextInputHandlerBase::EnsureSecureEventInputDisabled()
 void
 TextInputHandlerBase::KeyEventState::InitKeyEvent(
                                        TextInputHandlerBase* aHandler,
-                                       WidgetKeyboardEvent& aKeyEvent,
-                                       bool aIsProcessedByIME)
+                                       WidgetKeyboardEvent& aKeyEvent)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
@@ -5197,8 +4919,7 @@ TextInputHandlerBase::KeyEventState::InitKeyEvent(
   }
 
   aKeyEvent.mUniqueId = mUniqueId;
-  aHandler->InitKeyEvent(nativeEvent, aKeyEvent, aIsProcessedByIME,
-                         mInsertString);
+  aHandler->InitKeyEvent(nativeEvent, aKeyEvent, mInsertString);
 
   NS_OBJC_END_TRY_ABORT_BLOCK;
 }
diff --git a/widget/gtk/IMContextWrapper.cpp b/widget/gtk/IMContextWrapper.cpp
index ba64e3c25a9e..33552fbe2c21 100644
--- a/widget/gtk/IMContextWrapper.cpp
+++ b/widget/gtk/IMContextWrapper.cpp
@@ -175,8 +175,6 @@ IMContextWrapper::IMContextWrapper(nsWindow* aOwnerWindow)
     , mProcessingKeyEvent(nullptr)
     , mCompositionState(eCompositionState_NotComposing)
     , mIsIMFocused(false)
-    , mFallbackToKeyEvent(false)
-    , mKeyboardEventWasDispatched(false)
     , mIsDeletingSurrounding(false)
     , mLayoutChanged(false)
     , mSetCursorPositionOnKeyEvent(true)
@@ -486,7 +484,7 @@ IMContextWrapper::OnBlurWindow(nsWindow* aWindow)
 bool
 IMContextWrapper::OnKeyEvent(nsWindow* aCaller,
                              GdkEventKey* aEvent,
-                             bool aKeyboardEventWasDispatched /* = false */)
+                             bool aKeyDownEventWasSent /* = false */)
 {
     NS_PRECONDITION(aEvent, "aEvent must be non-null");
 
@@ -496,10 +494,10 @@ IMContextWrapper::OnKeyEvent(nsWindow* aCaller,
     }
 
     MOZ_LOG(gGtkIMLog, LogLevel::Info,
-        ("0x%p OnKeyEvent(aCaller=0x%p, aKeyboardEventWasDispatched=%s), "
+        ("0x%p OnKeyEvent(aCaller=0x%p, aKeyDownEventWasSent=%s), "
          "mCompositionState=%s, current context=0x%p, active context=0x%p, "
          "aEvent(0x%p): { type=%s, keyval=%s, unicode=0x%X }",
-         this, aCaller, ToChar(aKeyboardEventWasDispatched),
+         this, aCaller, ToChar(aKeyDownEventWasSent),
          GetCompositionStateName(), GetCurrentContext(), GetActiveContext(),
          aEvent, GetEventType(aEvent), gdk_keyval_name(aEvent->keyval),
          gdk_keyval_to_unicode(aEvent->keyval)));
@@ -527,51 +525,49 @@ IMContextWrapper::OnKeyEvent(nsWindow* aCaller,
         mSetCursorPositionOnKeyEvent = false;
     }
 
-    mKeyboardEventWasDispatched = aKeyboardEventWasDispatched;
-    mFallbackToKeyEvent = false;
+    mKeyDownEventWasSent = aKeyDownEventWasSent;
+    mFilterKeyEvent = true;
     mProcessingKeyEvent = aEvent;
     gboolean isFiltered =
         gtk_im_context_filter_keypress(currentContext, aEvent);
-
-    // The caller of this shouldn't handle aEvent anymore if we've dispatched
-    // composition events or modified content with other events.
-    bool filterThisEvent = isFiltered && !mFallbackToKeyEvent;
-
-    if (IsComposingOnCurrentContext() && !isFiltered &&
-        aEvent->type == GDK_KEY_PRESS &&
-        mDispatchedCompositionString.IsEmpty()) {
-        // A Hangul input engine for SCIM doesn't emit preedit_end
-        // signal even when composition string becomes empty.  On the
-        // other hand, we should allow to make composition with empty
-        // string for other languages because there *might* be such
-        // IM.  For compromising this issue, we should dispatch
-        // compositionend event, however, we don't need to reset IM
-        // actually.
-        // NOTE: Don't dispatch key events as "processed by IME" since
-        // we need to dispatch keyboard events as IME wasn't handled it.
-        mProcessingKeyEvent = nullptr;
-        DispatchCompositionCommitEvent(currentContext, &EmptyString());
-        mProcessingKeyEvent = aEvent;
-        // In this case, even though we handle the keyboard event here,
-        // but we should dispatch keydown event as
-        filterThisEvent = false;
-    }
-
-    // If IME handled the key event but we've not dispatched eKeyDown nor
-    // eKeyUp event yet, we need to dispatch here because the caller won't
-    // do it.
-    if (filterThisEvent) {
-        MaybeDispatchKeyEventAsProcessedByIME();
-        // Be aware, the widget might have been gone here.
-    }
-
     mProcessingKeyEvent = nullptr;
 
+    // We filter the key event if the event was not committed (because
+    // it's probably part of a composition) or if the key event was
+    // committed _and_ changed.  This way we still let key press
+    // events go through as simple key press events instead of
+    // composed characters.
+    bool filterThisEvent = isFiltered && mFilterKeyEvent;
+
+    if (IsComposingOnCurrentContext() && !isFiltered) {
+        if (aEvent->type == GDK_KEY_PRESS) {
+            if (!mDispatchedCompositionString.IsEmpty()) {
+                // If there is composition string, we shouldn't dispatch
+                // any keydown events during composition.
+                filterThisEvent = true;
+            } else {
+                // A Hangul input engine for SCIM doesn't emit preedit_end
+                // signal even when composition string becomes empty.  On the
+                // other hand, we should allow to make composition with empty
+                // string for other languages because there *might* be such
+                // IM.  For compromising this issue, we should dispatch
+                // compositionend event, however, we don't need to reset IM
+                // actually.
+                DispatchCompositionCommitEvent(currentContext, &EmptyString());
+                filterThisEvent = false;
+            }
+        } else {
+            // Key release event may not be consumed by IM, however, we
+            // shouldn't dispatch any keyup event during composition.
+            filterThisEvent = true;
+        }
+    }
+
     MOZ_LOG(gGtkIMLog, LogLevel::Debug,
         ("0x%p   OnKeyEvent(), succeeded, filterThisEvent=%s "
-         "(isFiltered=%s, mFallbackToKeyEvent=%s), mCompositionState=%s",
+         "(isFiltered=%s, mFilterKeyEvent=%s), mCompositionState=%s",
          this, ToChar(filterThisEvent), ToChar(isFiltered),
-         ToChar(mFallbackToKeyEvent), GetCompositionStateName()));
+         ToChar(mFilterKeyEvent), GetCompositionStateName()));
 
     return filterThisEvent;
 }
@@ -1306,14 +1302,11 @@ IMContextWrapper::OnCommitCompositionNative(GtkIMContext* aContext,
     }
 
     // If IME doesn't change their keyevent that generated this commit,
-    // we should treat that IME didn't handle the key event because
-    // web applications want to receive "keydown" and "keypress" event
-    // in such case.
+    // don't send it through XIM - just send it as a normal key press
+    // event.
     // NOTE: While a key event is being handled, this might be caused on
     // current context.  Otherwise, this may be caused on active context.
-    if (!IsComposingOn(aContext) &&
-        mProcessingKeyEvent &&
-        mProcessingKeyEvent->type == GDK_KEY_PRESS &&
+    if (!IsComposingOn(aContext) && mProcessingKeyEvent &&
         aContext == GetCurrentContext()) {
         char keyval_utf8[8]; /* should have at least 6 bytes of space */
         gint keyval_utf8_len;
@@ -1328,9 +1321,7 @@ IMContextWrapper::OnCommitCompositionNative(GtkIMContext* aContext,
                 ("0x%p   OnCommitCompositionNative(), "
                  "we'll send normal key event",
                  this));
-            // In this case, eKeyDown and eKeyPress event should be dispatched
-            // by the caller of OnKeyEvent().
-            mFallbackToKeyEvent = true;
+            mFilterKeyEvent = false;
             return;
         }
     }
@@ -1364,65 +1355,6 @@ IMContextWrapper::GetCompositionString(GtkIMContext* aContext,
     g_free(preedit_string);
 }
 
-bool
-IMContextWrapper::MaybeDispatchKeyEventAsProcessedByIME()
-{
-    if (!mProcessingKeyEvent || mKeyboardEventWasDispatched ||
-        !mLastFocusedWindow) {
-        return true;
-    }
-
-    // A "keydown" or "keyup" event handler may change focus with the
-    // following event.  In such case, we need to cancel this composition.
-    // So, we need to store IM context now because mComposingContext may be
-    // overwritten with different context if calling this method recursively.
-    // Note that we don't need to grab the context here because |context|
-    // will be used only for checking if it's same as mComposingContext.
-    GtkIMContext* oldCurrentContext = GetCurrentContext();
-    GtkIMContext* oldComposingContext = mComposingContext;
-
-    RefPtr<nsWindow> lastFocusedWindow(mLastFocusedWindow);
-    mKeyboardEventWasDispatched = true;
-
-    // FYI: We should ignore if default of preceding keydown or keyup event is
-    //      prevented since even on the other browsers, web applications
-    //      cannot cancel the following composition event.
-    //      Spec bug: https://github.com/w3c/uievents/issues/180
-    bool isCancelled;
-    lastFocusedWindow->DispatchKeyDownOrKeyUpEvent(mProcessingKeyEvent, true,
-                                                   &isCancelled);
-    MOZ_LOG(gGtkIMLog, LogLevel::Debug,
-        ("0x%p   MaybeDispatchKeyEventAsProcessedByIME(), keydown or keyup "
-         "event is dispatched",
-         this));
-    if (lastFocusedWindow->IsDestroyed() ||
-        lastFocusedWindow != mLastFocusedWindow) {
-        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-            ("0x%p   MaybeDispatchKeyEventAsProcessedByIME(), Warning, the "
-             "focused widget was destroyed/changed by a key event",
-             this));
-        return false;
-    }
-
-    // If the dispatched keydown event caused moving focus and that also
-    // caused changing active context, we need to cancel composition here.
-    if (GetCurrentContext() != oldCurrentContext) {
-        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-            ("0x%p   MaybeDispatchKeyEventAsProcessedByIME(), Warning, the key "
-             "event causes changing active IM context",
-             this));
-        if (mComposingContext == oldComposingContext) {
-            // Only when the context is still composing, we should call
-            // ResetIME() here.  Otherwise, it should've already been
-            // cleaned up.
-            ResetIME();
-        }
-        return false;
-    }
-
-    return true;
-}
-
 bool
 IMContextWrapper::DispatchCompositionStart(GtkIMContext* aContext)
 {
@@ -1467,16 +1399,50 @@ IMContextWrapper::DispatchCompositionStart(GtkIMContext* aContext)
     mCompositionStart = mSelection.mOffset;
     mDispatchedCompositionString.Truncate();
 
-    // If this composition is started by a key press, we need to dispatch
-    // eKeyDown or eKeyUp event before dispatching eCompositionStart event.
-    // Note that dispatching a keyboard event which is marked as "processed
-    // by IME" is okay since Chromium also dispatches keyboard event as so.
-    if (!MaybeDispatchKeyEventAsProcessedByIME()) {
-        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-            ("0x%p   DispatchCompositionStart(), Warning, "
-             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
+    if (mProcessingKeyEvent && !mKeyDownEventWasSent &&
+        mProcessingKeyEvent->type == GDK_KEY_PRESS) {
+        // A keydown event handler may change focus with the following keydown
+        // event.  In such case, we need to cancel this composition.  So, we
+        // need to store IM context now because mComposingContext may be
+        // overwritten with different context if calling this method
+        // recursively.
+        // Note that we don't need to grab the context here because |context|
+        // will be used only for checking if it's same as mComposingContext.
+        GtkIMContext* context = mComposingContext;
+
+        // If this composition is started by a native keydown event, we need to
+        // dispatch our keydown event here (before composition start).
+        bool isCancelled;
+        mLastFocusedWindow->DispatchKeyDownEvent(mProcessingKeyEvent,
+                                                 &isCancelled);
+        MOZ_LOG(gGtkIMLog, LogLevel::Debug,
+            ("0x%p   DispatchCompositionStart(), preceding keydown event is "
+             "dispatched",
              this));
-        return false;
+        if (lastFocusedWindow->IsDestroyed() ||
+            lastFocusedWindow != mLastFocusedWindow) {
+            MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+                ("0x%p   DispatchCompositionStart(), Warning, the focused "
+                 "widget was destroyed/changed by keydown event",
+                 this));
+            return false;
+        }
+
+        // If the dispatched keydown event caused moving focus and that also
+        // caused changing active context, we need to cancel composition here.
+        if (GetCurrentContext() != context) {
+            MOZ_LOG(gGtkIMLog, LogLevel::Warning,
+                ("0x%p   DispatchCompositionStart(), Warning, the preceding "
+                 "keydown event causes changing active IM context",
+                 this));
+            if (mComposingContext == context) {
+                // Only when the context is still composing, we should call
+                // ResetIME() here.  Otherwise, it should've already been
+                // cleaned up.
+                ResetIME();
+            }
+            return false;
+        }
     }
 
     RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
@@ -1534,15 +1500,6 @@ IMContextWrapper::DispatchCompositionChangeEvent(
             return false;
         }
     }
-    // If this composition string change caused by a key press, we need to
-    // dispatch eKeyDown or eKeyUp before dispatching eCompositionChange event.
-    else if (!MaybeDispatchKeyEventAsProcessedByIME()) {
-        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-            ("0x%p   DispatchCompositionChangeEvent(), Warning, "
-             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
-             this));
-        return false;
-    }
 
     RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
     nsresult rv = dispatcher->BeginNativeInputTransaction();
@@ -1632,14 +1589,6 @@ IMContextWrapper::DispatchCompositionCommitEvent(
         return false;
     }
 
-    // TODO: We need special care to handle request to commit composition
-    //       by content while we're committing composition because we have
-    //       commit string information now but IME may not have composition
-    //       anymore.  Therefore, we may not be able to handle commit as
-    //       expected.  However, this is rare case because this situation
-    //       never occurs with remote content.  So, it's okay to fix this
-    //       issue later.  (Perhaps, TextEventDisptcher should do it for
-    //       all platforms.  E.g., creating WillCommitComposition()?)
     if (!IsComposing()) {
         if (!aCommitString || aCommitString->IsEmpty()) {
             MOZ_LOG(gGtkIMLog, LogLevel::Error,
@@ -1656,16 +1605,6 @@ IMContextWrapper::DispatchCompositionCommitEvent(
             return false;
         }
     }
-    // If this commit caused by a key press, we need to dispatch eKeyDown or
-    // eKeyUp before dispatching composition events.
-    else if (!MaybeDispatchKeyEventAsProcessedByIME()) {
-        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-            ("0x%p   DispatchCompositionCommitEvent(), Warning, "
-             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
-             this));
-        mCompositionState = eCompositionState_NotComposing;
-        return false;
-    }
 
     RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
     nsresult rv = dispatcher->BeginNativeInputTransaction();
@@ -2360,16 +2299,6 @@ IMContextWrapper::DeleteText(GtkIMContext* aContext,
         return NS_ERROR_FAILURE;
     }
 
-    // If this deleting text caused by a key press, we need to dispatch
-    // eKeyDown or eKeyUp before dispatching eContentCommandDelete event.
-    if (!MaybeDispatchKeyEventAsProcessedByIME()) {
-        MOZ_LOG(gGtkIMLog, LogLevel::Warning,
-            ("0x%p   DeleteText(), Warning, "
-             "MaybeDispatchKeyEventAsProcessedByIME() returned false",
-             this));
-        return NS_ERROR_FAILURE;
-    }
-
     // Delete the selection
     WidgetContentCommandEvent contentCommandEvent(true, eContentCommandDelete,
                                                   mLastFocusedWindow);
diff --git a/widget/gtk/IMContextWrapper.h b/widget/gtk/IMContextWrapper.h
index 241319cee9ea..17c758092410 100644
--- a/widget/gtk/IMContextWrapper.h
+++ b/widget/gtk/IMContextWrapper.h
@@ -65,26 +65,13 @@ public:
     void OnSelectionChange(nsWindow* aCaller,
                            const IMENotification& aIMENotification);
 
-    /**
-     * OnKeyEvent() is called when aWindow gets a native key press event or a
-     * native key release event.  If this returns true, the key event was
-     * filtered by IME.  Otherwise, this returns false.
-     * NOTE: When the native key press event starts composition, this returns
-     *       true but dispatches an eKeyDown event or eKeyUp event before
-     *       dispatching composition events or content command event.
-     *
-     * @param aWindow                       A window on which user operate the
-     *                                      key.
-     * @param aEvent                        A native key press or release
-     *                                      event.
-     * @param aKeyboardEventWasDispatched   true if eKeyDown or eKeyUp event
-     *                                      for aEvent has already been
-     *                                      dispatched.  In this case,
-     *                                      this class doesn't dispatch
-     *                                      keyboard event anymore.
-     */
+    // OnKeyEvent is called when aWindow gets a native key press event or a
+    // native key release event.  If this returns TRUE, the key event was
+    // filtered by IME.  Otherwise, this returns FALSE.
+    // NOTE: When the keypress event starts composition, this returns TRUE but
+    //       this dispatches keydown event before compositionstart event.
     bool OnKeyEvent(nsWindow* aWindow, GdkEventKey* aEvent,
-                    bool aKeyboardEventWasDispatched = false);
+                      bool aKeyDownEventWasSent = false);
 
     // IME related nsIWidget methods.
     nsresult EndIMEComposition(nsWindow* aCaller);
@@ -276,20 +263,16 @@ protected:
     // mIsIMFocused is set to TRUE when we call gtk_im_context_focus_in(). And
     // it's set to FALSE when we call gtk_im_context_focus_out().
     bool mIsIMFocused;
-    // mFallbackToKeyEvent is set to false when this class starts to handle
-    // a native key event (at that time, mProcessingKeyEvent is set to the
-    // native event).  If active IME just commits composition with a character
-    // which is produced by the key with current keyboard layout, this is set
-    // to true.
-    bool mFallbackToKeyEvent;
-    // mKeyboardEventWasDispatched is used by OnKeyEvent() and
-    // MaybeDispatchKeyEventAsProcessedByIME().
-    // MaybeDispatchKeyEventAsProcessedByIME() dispatches an eKeyDown or
-    // eKeyUp event event if the composition is caused by a native
-    // key press event.  If this is true, a keyboard event has been dispatched
-    // for the native event.  If so, MaybeDispatchKeyEventAsProcessedByIME()
-    // won't dispatch keyboard event anymore.
-    bool mKeyboardEventWasDispatched;
+    // mFilterKeyEvent is used by OnKeyEvent().  If the commit event should
+    // be processed as simple key event, this is set to TRUE by the commit
+    // handler.
+    bool mFilterKeyEvent;
+    // mKeyDownEventWasSent is used by OnKeyEvent() and
+    // DispatchCompositionStart().  DispatchCompositionStart() dispatches
+    // a keydown event if the composition start is caused by a native
+    // keypress event.  If this is true, the keydown event has been dispatched.
+    // Then, DispatchCompositionStart() doesn't dispatch keydown event.
+    bool mKeyDownEventWasSent;
     // mIsDeletingSurrounding is true while OnDeleteSurroundingNative() is
     // trying to delete the surrounding text.
     bool mIsDeletingSurrounding;
@@ -460,27 +443,11 @@ protected:
      *    Following methods dispatch gecko events.  Then, the focused widget
      *    can be destroyed, and also it can be stolen focus.  If they returns
      *    FALSE, callers cannot continue the composition.
-     *      - MaybeDispatchKeyEventAsProcessedByIME
      *      - DispatchCompositionStart
      *      - DispatchCompositionChangeEvent
      *      - DispatchCompositionCommitEvent
      */
 
-    /**
-     * Dispatch an eKeyDown or eKeyUp event whose mKeyCode value is
-     * NS_VK_PROCESSKEY and mKeyNameIndex is KEY_NAME_INDEX_Process if
-     * mProcessingKeyEvent is not nullptr and mKeyboardEventWasDispatched is
-     * still false.  If this dispatches a keyboard event, this sets
-     * mKeyboardEventWasDispatched to true.
-     *
-     * @return                      If the caller can continue to handle
-     *                              composition, returns true.  Otherwise,
-     *                              false.  For example, if focus is moved
-     *                              by dispatched keyboard event, returns
-     *                              false.
-     */
-    bool MaybeDispatchKeyEventAsProcessedByIME();
-
     /**
      * Dispatches a composition start event.
      *
diff --git a/widget/gtk/nsGtkKeyUtils.cpp b/widget/gtk/nsGtkKeyUtils.cpp
index 6a02b9a1bc67..a336c1ad6c92 100644
--- a/widget/gtk/nsGtkKeyUtils.cpp
+++ b/widget/gtk/nsGtkKeyUtils.cpp
@@ -931,19 +931,14 @@ KeymapWrapper::ComputeDOMCodeNameIndex(const GdkEventKey* aGdkKeyEvent)
 
 /* static */ void
 KeymapWrapper::InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
-                            GdkEventKey* aGdkKeyEvent,
-                            bool aIsProcessedByIME)
+                            GdkEventKey* aGdkKeyEvent)
 {
-    MOZ_ASSERT(!aIsProcessedByIME || aKeyEvent.mMessage != eKeyPress,
-      "If the key event is handled by IME, keypress event shouldn't be fired");
-
     KeymapWrapper* keymapWrapper = GetInstance();
 
     aKeyEvent.mCodeNameIndex = ComputeDOMCodeNameIndex(aGdkKeyEvent);
     MOZ_ASSERT(aKeyEvent.mCodeNameIndex != CODE_NAME_INDEX_USE_STRING);
     aKeyEvent.mKeyNameIndex =
-        aIsProcessedByIME ? KEY_NAME_INDEX_Process :
-                            keymapWrapper->ComputeDOMKeyNameIndex(aGdkKeyEvent);
+        keymapWrapper->ComputeDOMKeyNameIndex(aGdkKeyEvent);
     if (aKeyEvent.mKeyNameIndex == KEY_NAME_INDEX_Unidentified) {
         uint32_t charCode = GetCharCodeFor(aGdkKeyEvent);
         if (!charCode) {
@@ -956,11 +951,10 @@ KeymapWrapper::InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
             AppendUCS4ToUTF16(charCode, aKeyEvent.mKeyValue);
         }
     }
+    aKeyEvent.mKeyCode = ComputeDOMKeyCode(aGdkKeyEvent);
 
-    if (aIsProcessedByIME) {
-        aKeyEvent.mKeyCode = NS_VK_PROCESSKEY;
-    } else if (aKeyEvent.mKeyNameIndex != KEY_NAME_INDEX_USE_STRING ||
-               aKeyEvent.mMessage != eKeyPress) {
+    if (aKeyEvent.mKeyNameIndex != KEY_NAME_INDEX_USE_STRING ||
+        aKeyEvent.mMessage != eKeyPress) {
         aKeyEvent.mKeyCode = ComputeDOMKeyCode(aGdkKeyEvent);
     } else {
         aKeyEvent.mKeyCode = 0;
diff --git a/widget/gtk/nsGtkKeyUtils.h b/widget/gtk/nsGtkKeyUtils.h
index a1b9e53f0daa..3dc8a4f6a936 100644
--- a/widget/gtk/nsGtkKeyUtils.h
+++ b/widget/gtk/nsGtkKeyUtils.h
@@ -131,11 +131,9 @@ public:
      * @param aKeyEvent         It's an WidgetKeyboardEvent which needs to be
      *                          initialized.
      * @param aGdkKeyEvent      A native GDK key event.
-     * @param aIsProcessedByIME true if aGdkKeyEvent is handled by IME.
      */
     static void InitKeyEvent(WidgetKeyboardEvent& aKeyEvent,
-                             GdkEventKey* aGdkKeyEvent,
-                             bool aIsProcessedByIME);
+                             GdkEventKey* aGdkKeyEvent);
 
     /**
      * WillDispatchKeyboardEvent() is called via
diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index ae342a557b6b..dcbff364916b 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -2937,15 +2937,13 @@ IsCtrlAltTab(GdkEventKey *aEvent)
 }
 
 bool
-nsWindow::DispatchKeyDownOrKeyUpEvent(GdkEventKey* aEvent,
-                                      bool aIsProcessedByIME,
-                                      bool* aIsCancelled)
+nsWindow::DispatchKeyDownEvent(GdkEventKey *aEvent, bool *aCancelled)
 {
-    MOZ_ASSERT(aIsCancelled, "aCancelled must not be null");
+    NS_PRECONDITION(aCancelled, "aCancelled must not be null");
 
-    *aIsCancelled = false;
+    *aCancelled = false;
 
-    if (aEvent->type == GDK_KEY_PRESS && IsCtrlAltTab(aEvent)) {
+    if (IsCtrlAltTab(aEvent)) {
         return false;
     }
 
@@ -2955,14 +2953,13 @@ nsWindow::DispatchKeyDownOrKeyUpEvent(GdkEventKey* aEvent,
         return FALSE;
     }
 
-    EventMessage message =
-        aEvent->type == GDK_KEY_PRESS ? eKeyDown : eKeyUp;
-    WidgetKeyboardEvent keyEvent(true, message, this);
-    KeymapWrapper::InitKeyEvent(keyEvent, aEvent, aIsProcessedByIME);
+    WidgetKeyboardEvent keydownEvent(true, eKeyDown, this);
+    KeymapWrapper::InitKeyEvent(keydownEvent, aEvent);
     nsEventStatus status = nsEventStatus_eIgnore;
     bool dispatched =
-        dispatcher->DispatchKeyboardEvent(message, keyEvent, status, aEvent);
-    *aIsCancelled = (status == nsEventStatus_eConsumeNoDefault);
+        dispatcher->DispatchKeyboardEvent(eKeyDown, keydownEvent,
+                                          status, aEvent);
+    *aCancelled = (status == nsEventStatus_eConsumeNoDefault);
     return dispatched ? TRUE : FALSE;
 }
 
@@ -3048,7 +3045,7 @@ nsWindow::OnKeyPressEvent(GdkEventKey *aEvent)
     // KEYDOWN -> KEYPRESS -> KEYUP -> KEYDOWN -> KEYPRESS -> KEYUP...
 
     bool isKeyDownCancelled = false;
-    if (DispatchKeyDownOrKeyUpEvent(aEvent, false, &isKeyDownCancelled) &&
+    if (DispatchKeyDownEvent(aEvent, &isKeyDownCancelled) &&
         (MOZ_UNLIKELY(mIsDestroyed) || isKeyDownCancelled)) {
         return TRUE;
     }
@@ -3097,7 +3094,7 @@ nsWindow::OnKeyPressEvent(GdkEventKey *aEvent)
     }
 
     WidgetKeyboardEvent keypressEvent(true, eKeyPress, this);
-    KeymapWrapper::InitKeyEvent(keypressEvent, aEvent, false);
+    KeymapWrapper::InitKeyEvent(keypressEvent, aEvent);
 
     // before we dispatch a key, check if it's the context menu key.
     // If so, send a context menu key event instead.
@@ -3181,7 +3178,7 @@ nsWindow::MaybeDispatchContextMenuEvent(const GdkEventKey* aEvent)
 }
 
 gboolean
-nsWindow::OnKeyReleaseEvent(GdkEventKey* aEvent)
+nsWindow::OnKeyReleaseEvent(GdkEventKey *aEvent)
 {
     LOGFOCUS(("OnKeyReleaseEvent [%p]\n", (void *)this));
 
@@ -3189,11 +3186,17 @@ nsWindow::OnKeyReleaseEvent(GdkEventKey* aEvent)
         return TRUE;
     }
 
-    bool isCancelled = false;
-    if (NS_WARN_IF(!DispatchKeyDownOrKeyUpEvent(aEvent, false, &isCancelled))) {
-        return FALSE;
+    RefPtr<TextEventDispatcher> dispatcher = GetTextEventDispatcher();
+    nsresult rv = dispatcher->BeginNativeInputTransaction();
+    if (NS_WARN_IF(NS_FAILED(rv))) {
+        return false;
     }
 
+    WidgetKeyboardEvent keyupEvent(true, eKeyUp, this);
+    KeymapWrapper::InitKeyEvent(keyupEvent, aEvent);
+    nsEventStatus status = nsEventStatus_eIgnore;
+    dispatcher->DispatchKeyboardEvent(eKeyUp, keyupEvent, status, aEvent);
+
     return TRUE;
 }
 
diff --git a/widget/gtk/nsWindow.h b/widget/gtk/nsWindow.h
index e7ed6f47c044..0d57c156f49f 100644
--- a/widget/gtk/nsWindow.h
+++ b/widget/gtk/nsWindow.h
@@ -278,20 +278,10 @@ public:
                                          guint aTime);
     static void        UpdateDragStatus (GdkDragContext *aDragContext,
                                          nsIDragService *aDragService);
-    /**
-     * DispatchKeyDownOrKeyUpEvent() dispatches eKeyDown or eKeyUp event.
-     *
-     * @param aEvent            A native GDK_KEY_PRESS or GDK_KEY_RELEASE
-     *                          event.
-     * @param aProcessedByIME   true if the event is handled by IME.
-     * @param aIsCancelled      [Out] true if the default is prevented.
-     * @return                  true if eKeyDown event is actually dispatched.
-     *                          Otherwise, false.
-     */
-    bool DispatchKeyDownOrKeyUpEvent(GdkEventKey* aEvent,
-                                     bool aProcessedByIME,
-                                     bool* aIsCancelled);
-
+    // If this dispatched the keydown event actually, this returns TRUE,
+    // otherwise, FALSE.
+    bool               DispatchKeyDownEvent(GdkEventKey *aEvent,
+                                            bool *aIsCancelled);
     WidgetEventTime    GetWidgetEventTime(guint32 aEventTime);
     mozilla::TimeStamp GetEventTimeStamp(guint32 aEventTime);
     mozilla::CurrentX11TimeGetter* GetCurrentTimeGetter();
diff --git a/widget/tests/test_keycodes.xul b/widget/tests/test_keycodes.xul
index 694c8ef476ed..7ac53d57e17c 100644
--- a/widget/tests/test_keycodes.xul
+++ b/widget/tests/test_keycodes.xul
@@ -3023,10 +3023,10 @@ function* runKeyEventTests()
     const WIN_VK_PROCESSKEY_WITH_SC_A = WIN_VK_PROCESSKEY | 0x001E0000;
     yield testKey({layout:KEYBOARD_LAYOUT_EN_US, keyCode:WIN_VK_PROCESSKEY_WITH_SC_A,
                    modifiers:{}, chars:"a"},
-                  ["a", "a", "Process"], "KeyA", KeyboardEvent.DOM_VK_PROCESSKEY, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
+                  ["a", "a", "Unidentified" /* TODO: Process */], "KeyA", 0 /* TODO: 0xE5 */, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
     yield testKey({layout:KEYBOARD_LAYOUT_EN_US, keyCode:WIN_VK_PROCESSKEY_WITH_SC_A,
                    modifiers:{altKey:1}, chars:"a"},
-                  ["a", "a", "Process"], "KeyA", KeyboardEvent.DOM_VK_PROCESSKEY, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
+                  ["a", "a", "Unidentified" /* TODO: Process */], "KeyA", 0 /* TODO: 0xE5 */, "a", SHOULD_DELIVER_ALL, KeyboardEvent.DOM_KEY_LOCATION_STANDARD);
 
     // US
     // Alphabet
diff --git a/widget/windows/KeyboardLayout.cpp b/widget/windows/KeyboardLayout.cpp
index 2f7c43695f44..947e914e4bef 100644
--- a/widget/windows/KeyboardLayout.cpp
+++ b/widget/windows/KeyboardLayout.cpp
@@ -4805,7 +4805,7 @@ KeyboardLayout::ConvertNativeKeyCodeToDOMKeyCode(UINT aNativeKeyCode) const
 
     // VK_PROCESSKEY means IME already consumed the key event.
     case VK_PROCESSKEY:
-      return NS_VK_PROCESSKEY;
+      return 0;
     // VK_PACKET is generated by SendInput() API, we don't need to
     // care this message as key event.
     case VK_PACKET:

From 399b4424de28bd11a6b2ccabc478a7d80d258b57 Mon Sep 17 00:00:00 2001
From: Sylvestre Ledru <sledru@mozilla.com>
Date: Thu, 8 Mar 2018 10:51:42 +0100
Subject: [PATCH 42/50] Bug 1444048 - Codespell: ignore the ignored typos by
 moving to quiet-level=4 r=standard8

MozReview-Commit-ID: HpIOkKh6SQQ

--HG--
extra : rebase_source : 9d53382d86bb877f4d030a1b9bda30fda2acceb8
---
 tools/lint/spell/__init__.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/lint/spell/__init__.py b/tools/lint/spell/__init__.py
index c870511b465a..7ed5739b3625 100644
--- a/tools/lint/spell/__init__.py
+++ b/tools/lint/spell/__init__.py
@@ -103,7 +103,9 @@ def lint(paths, config, fix=None, **lintargs):
                 # Silence some warnings:
                 # 1: disable warnings about wrong encoding
                 # 2: disable warnings about binary file
-                '--quiet-level=3',
+		# 4: shut down warnings about automatic fixes
+                #    that were disabled in dictionary.
+                '--quiet-level=4',
                 ]
 
 # Disabled for now because of

From e0a0eed1653a58d145acdcbfe642fcd3c2e939b8 Mon Sep 17 00:00:00 2001
From: ffxbld <release@mozilla.com>
Date: Mon, 12 Mar 2018 13:18:08 +0000
Subject: [PATCH 43/50] No bug - Tagging mozilla-central
 fdd1a0082c71673239fc2f3a6a93de889c07a1be with FIREFOX_NIGHTLY_60_END
 a=release DONTBUILD CLOSED TREE

---
 .hgtags | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.hgtags b/.hgtags
index 549ffebb494e..dbe7fa766956 100644
--- a/.hgtags
+++ b/.hgtags
@@ -140,3 +140,4 @@ f7e9777221a34f9f23c2e4933307eb38b621b679 FIREFOX_NIGHTLY_57_END
 1f91961bb79ad06fd4caef9e5dfd546afd5bf42c FIREFOX_NIGHTLY_58_END
 5faab9e619901b1513fd4ca137747231be550def FIREFOX_NIGHTLY_59_END
 e33efdb3e1517d521deb949de3fcd6d9946ea440 FIREFOX_BETA_60_BASE
+fdd1a0082c71673239fc2f3a6a93de889c07a1be FIREFOX_NIGHTLY_60_END

From 99df6dad057b94c2ac4d8b12f7b0b3a7fdf25d04 Mon Sep 17 00:00:00 2001
From: ffxbld <release@mozilla.com>
Date: Mon, 12 Mar 2018 13:20:48 +0000
Subject: [PATCH 44/50] Update configs. IGNORE BROKEN CHANGESETS CLOSED TREE NO
 BUG a=release ba=release

---
 CLOBBER                            | 2 +-
 browser/config/version.txt         | 2 +-
 browser/config/version_display.txt | 2 +-
 config/milestone.txt               | 2 +-
 services/sync/modules/constants.js | 2 +-
 xpcom/components/Module.h          | 2 +-
 6 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/CLOBBER b/CLOBBER
index 131c577db7c0..d4cdfaff33de 100644
--- a/CLOBBER
+++ b/CLOBBER
@@ -22,4 +22,4 @@
 # changes to stick? As of bug 928195, this shouldn't be necessary! Please
 # don't change CLOBBER for WebIDL changes any more.
 
-Bug 1443983: Removing addoncompat.manifest requires clobber.
+Merge day clobber
\ No newline at end of file
diff --git a/browser/config/version.txt b/browser/config/version.txt
index f391c39cf0e9..72814c166863 100644
--- a/browser/config/version.txt
+++ b/browser/config/version.txt
@@ -1 +1 @@
-60.0a1
+61.0a1
diff --git a/browser/config/version_display.txt b/browser/config/version_display.txt
index f391c39cf0e9..72814c166863 100644
--- a/browser/config/version_display.txt
+++ b/browser/config/version_display.txt
@@ -1 +1 @@
-60.0a1
+61.0a1
diff --git a/config/milestone.txt b/config/milestone.txt
index 91e46a9e3f2a..afde1c4c75dc 100644
--- a/config/milestone.txt
+++ b/config/milestone.txt
@@ -10,4 +10,4 @@
 # hardcoded milestones in the tree from these two files.
 #--------------------------------------------------------
 
-60.0a1
+61.0a1
diff --git a/services/sync/modules/constants.js b/services/sync/modules/constants.js
index 61a04f3785c7..3aed541fd368 100644
--- a/services/sync/modules/constants.js
+++ b/services/sync/modules/constants.js
@@ -8,7 +8,7 @@ for (let [key, val] of Object.entries({
 
 // Don't manually modify this line, as it is automatically replaced on merge day
 // by the gecko_migration.py script.
-WEAVE_VERSION: "1.62.0",
+WEAVE_VERSION: "1.63.0",
 
 // Sync Server API version that the client supports.
 SYNC_API_VERSION:                      "1.5",
diff --git a/xpcom/components/Module.h b/xpcom/components/Module.h
index 24b7d510830f..374d1323f132 100644
--- a/xpcom/components/Module.h
+++ b/xpcom/components/Module.h
@@ -22,7 +22,7 @@ namespace mozilla {
  */
 struct Module
 {
-  static const unsigned int kVersion = 60;
+  static const unsigned int kVersion = 61;
 
   struct CIDEntry;
 

From 6c4226352cb8ae93904f602f852f587268d97588 Mon Sep 17 00:00:00 2001
From: Cosmin Sabou <csabou@mozilla.com>
Date: Mon, 12 Mar 2018 18:25:35 +0200
Subject: [PATCH 45/50] Backed out changeset cc9ebc5403e2 (bug 1444048) for
 linting opt failures on
 /builds/worker/checkouts/gecko/tools/lint/spell/__init__.py

---
 tools/lint/spell/__init__.py | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/lint/spell/__init__.py b/tools/lint/spell/__init__.py
index 7ed5739b3625..c870511b465a 100644
--- a/tools/lint/spell/__init__.py
+++ b/tools/lint/spell/__init__.py
@@ -103,9 +103,7 @@ def lint(paths, config, fix=None, **lintargs):
                 # Silence some warnings:
                 # 1: disable warnings about wrong encoding
                 # 2: disable warnings about binary file
-		# 4: shut down warnings about automatic fixes
-                #    that were disabled in dictionary.
-                '--quiet-level=4',
+                '--quiet-level=3',
                 ]
 
 # Disabled for now because of

From 34f58199be4d31c9c9f035cb7ec3273712b95826 Mon Sep 17 00:00:00 2001
From: ffxbld <none@none>
Date: Mon, 12 Mar 2018 12:54:26 -0700
Subject: [PATCH 46/50] No bug, Automated HSTS preload list update from host
 bld-linux64-spot-302 - a=hsts-update

---
 security/manager/ssl/nsSTSPreloadList.errors | 294 +++++++++----------
 security/manager/ssl/nsSTSPreloadList.inc    | 120 ++++----
 2 files changed, 187 insertions(+), 227 deletions(-)

diff --git a/security/manager/ssl/nsSTSPreloadList.errors b/security/manager/ssl/nsSTSPreloadList.errors
index 0dcd2892b771..2daa50386c4f 100644
--- a/security/manager/ssl/nsSTSPreloadList.errors
+++ b/security/manager/ssl/nsSTSPreloadList.errors
@@ -45,6 +45,7 @@
 4loc.us: could not connect to host
 4web-hosting.com: could not connect to host
 5000yz.com: could not connect to host
+517vpn.cn: could not connect to host
 52kb1.com: could not connect to host
 52neptune.com: could not connect to host
 5ece.de: could not connect to host
@@ -85,7 +86,9 @@ acwcerts.co.uk: could not connect to host
 ad-disruptio.fr: could not connect to host
 adamcoffee.net: could not connect to host
 adamdixon.co.uk: could not connect to host
+addcrazy.com: could not connect to host
 adec-emsa.ae: could not connect to host
+adrianajewelry.my: could not connect to host
 adult.properties: could not connect to host
 advaithnikhi.ml: could not connect to host
 advaithnikhi.tk: could not connect to host
@@ -102,8 +105,6 @@ agowa338.de: could not connect to host
 agrilinks.org: could not connect to host
 ahelos.tk: could not connect to host
 ahlz.sk: could not connect to host
-aibaoyou.com: could not connect to host
-aid-web.ch: could not connect to host
 aikenorganics.com: could not connect to host
 aim-consultants.com: could not connect to host
 airclass.com: could not connect to host
@@ -155,7 +156,6 @@ andronika.net: could not connect to host
 anecuni-club.com: could not connect to host
 anecuni-rec.com: could not connect to host
 angrydragonproductions.com: could not connect to host
-animojis.es: could not connect to host
 anitube-nocookie.ch: could not connect to host
 anivar.net: could not connect to host
 annetaan.fi: could not connect to host
@@ -168,7 +168,6 @@ appdrinks.com: could not connect to host
 apple.ax: could not connect to host
 apps4all.sytes.net: could not connect to host
 apptoutou.com: could not connect to host
-appzoojoo.be: could not connect to host
 aqqrate.com: could not connect to host
 area3.org: could not connect to host
 arent.kz: could not connect to host
@@ -194,12 +193,14 @@ assindia.nl: could not connect to host
 asthon.cn: could not connect to host
 astrath.net: could not connect to host
 astrea-voetbal-groningen.nl: could not connect to host
+asuhe.win: could not connect to host
 asuhe.xyz: could not connect to host
 async.be: could not connect to host
 at1.co: could not connect to host
 athi.pl: could not connect to host
 atigerseye.com: could not connect to host
 atlas-5.site: could not connect to host
+attendantdesign.com: could not connect to host
 attilagyorffy.com: could not connect to host
 aufmerksamkeitsstudie.com: could not connect to host
 augix.net: could not connect to host
@@ -215,11 +216,10 @@ autosearch.me: could not connect to host
 autostock.me: could not connect to host
 autostop-occasions.be: could not connect to host
 avdelivers.com: could not connect to host
-avernis.de: could not connect to host
-avi9526.pp.ua: could not connect to host
 avmo.pw: could not connect to host
 avonlearningcampus.com: could not connect to host
 avso.pw: could not connect to host
+avxo.pw: could not connect to host
 awan.tech: could not connect to host
 awei.pub: could not connect to host
 awf0.xyz: could not connect to host
@@ -231,6 +231,7 @@ babelfisch.eu: could not connect to host
 bacimg.com: could not connect to host
 badbee.cc: could not connect to host
 bailbondsaffordable.com: could not connect to host
+baldur.cc: could not connect to host
 balonmano.co: could not connect to host
 bandally.net: could not connect to host
 bandarifamily.com: could not connect to host
@@ -246,6 +247,7 @@ bbwteens.org: could not connect to host
 bcnet.com.hk: could not connect to host
 bcradio.org: could not connect to host
 bcrook.com: could not connect to host
+bcvps.com: could not connect to host
 bdsmxxxpics.com: could not connect to host
 beamitapp.com: could not connect to host
 beasel.biz: could not connect to host
@@ -278,6 +280,7 @@ bfrailwayclub.cf: could not connect to host
 bianinapiccanovias.com: could not connect to host
 bichonmaltes.com.br: could not connect to host
 bigerbio.com: could not connect to host
+bildschirmflackern.de: could not connect to host
 billigpoker.dk: could not connect to host
 billpro.com.au: could not connect to host
 binam.center: could not connect to host
@@ -286,7 +289,6 @@ binimo.com: could not connect to host
 biou.me: could not connect to host
 biovalue.eu: could not connect to host
 bip.gov.sa: could not connect to host
-biscoint.io: could not connect to host
 biscuits-rec.com: could not connect to host
 biscuits-shop.com: could not connect to host
 biswas.me: could not connect to host
@@ -323,7 +325,6 @@ bombsquad.studio: could not connect to host
 bonesserver.com: could not connect to host
 bonobo.cz: could not connect to host
 bookreport.ga: could not connect to host
-booter.es: could not connect to host
 boozinyan.com: could not connect to host
 borchers-media.de: could not connect to host
 borisbesemer.com: could not connect to host
@@ -349,8 +350,10 @@ bsalyzer.com: could not connect to host
 bsktweetup.info: could not connect to host
 bslim-e-boutique.com: could not connect to host
 bsuess.de: could not connect to host
+btcp.space: could not connect to host
 buck.com: could not connect to host
 buenotour.ru: could not connect to host
+buffalodrinkinggame.beer: could not connect to host
 bugsmashed.com: could not connect to host
 bugtrack.co.uk: could not connect to host
 buka.jp: could not connect to host
@@ -365,6 +368,7 @@ buyharpoon.com: could not connect to host
 buyhealth.shop: could not connect to host
 buyingsellingflorida.com: could not connect to host
 buyshoe.org: could not connect to host
+buywood.shop: could not connect to host
 bvexplained.co.uk: could not connect to host
 bxdev.me: could not connect to host
 by1898.com: could not connect to host
@@ -377,7 +381,6 @@ cafesg.net: could not connect to host
 caipai.fm: could not connect to host
 cal.goip.de: could not connect to host
 calculatoaresecondhand.xyz: could not connect to host
-calebmorris.com: could not connect to host
 callabs.net: could not connect to host
 calleveryday.com: could not connect to host
 callsigns.ca: could not connect to host
@@ -405,11 +408,9 @@ cdmon.tech: could not connect to host
 cdnk39.com: could not connect to host
 cee.io: could not connect to host
 cegfw.com: could not connect to host
-celuliteonline.com: could not connect to host
 cencalvia.org: could not connect to host
 centos.pub: could not connect to host
 centrallead.net: could not connect to host
-centrationgame.com: could not connect to host
 centrolavoro.org: could not connect to host
 cgtx.us: could not connect to host
 challengeskins.com: could not connect to host
@@ -419,7 +420,6 @@ channellife.asia: could not connect to host
 chaouby.com: could not connect to host
 charge.co: could not connect to host
 charmyadesara.com: could not connect to host
-charta-digitale-vernetzung.de: could not connect to host
 cheah.xyz: could not connect to host
 cheesefusion.com: could not connect to host
 chez-janine.de: could not connect to host
@@ -451,6 +451,7 @@ clickclock.cc: could not connect to host
 clintonbloodworth.com: could not connect to host
 cloudberlin.goip.de: could not connect to host
 cloudbleed.info: could not connect to host
+cloudfiles.at: could not connect to host
 cloudimproved.com: could not connect to host
 cloudwarez.xyz: could not connect to host
 clownish.co.il: could not connect to host
@@ -470,7 +471,6 @@ coccinellaskitchen.de: could not connect to host
 coccinellaskitchen.it: could not connect to host
 codeloop.pw: could not connect to host
 codenlife.xyz: could not connect to host
-codeofhonor.tech: could not connect to host
 codercross.com: could not connect to host
 coderhangout.com: could not connect to host
 codewiz.xyz: could not connect to host
@@ -481,6 +481,7 @@ collins.kg: could not connect to host
 coloppe.com: could not connect to host
 com-in.de: could not connect to host
 com.cc: could not connect to host
+comalia.com: could not connect to host
 combatshield.cz: could not connect to host
 comicrelief.com: could not connect to host
 communityflow.info: could not connect to host
@@ -504,8 +505,8 @@ cosplayer.com: could not connect to host
 cotta.dk: could not connect to host
 coumoul.fr: could not connect to host
 cpaneltips.com: could not connect to host
-crackcat.de: could not connect to host
 crackslut.eu: could not connect to host
+craftination.net: could not connect to host
 crashsec.com: could not connect to host
 credential.eu: could not connect to host
 cristianhares.com: could not connect to host
@@ -524,7 +525,6 @@ cselzer.com: could not connect to host
 csgo77.com: could not connect to host
 csilies.de: could not connect to host
 cspeti.hu: could not connect to host
-ctj.im: could not connect to host
 cunha.be: could not connect to host
 cuni-cuni-club.com: could not connect to host
 cuni-rec.com: could not connect to host
@@ -559,6 +559,7 @@ dashboard.yt: could not connect to host
 data-detox.com: could not connect to host
 datastream.re: could not connect to host
 datorb.com: could not connect to host
+davetempleton.com: could not connect to host
 davidgreig.uk: could not connect to host
 davidscherzer.at: could not connect to host
 davidstuff.net: could not connect to host
@@ -580,6 +581,7 @@ decoyrouting.com: could not connect to host
 dedietrich-asia.com: could not connect to host
 deepcreampie.com: could not connect to host
 deeps.cat: could not connect to host
+delfic.org: could not connect to host
 deloittequant.com: could not connect to host
 depedtayo.ph: could not connect to host
 derchris.me: could not connect to host
@@ -592,13 +594,11 @@ detecte.ch: could not connect to host
 detectefuite.ch: could not connect to host
 devdesco.com: could not connect to host
 developersclub.website: could not connect to host
-devonsawatzky.ca: could not connect to host
 devops.moe: could not connect to host
 dezintranet.com: could not connect to host
 dhl-smart.ch: could not connect to host
 dhub.xyz: could not connect to host
 dhxxls.com: could not connect to host
-dibiphp.com: could not connect to host
 diceduels.com: could not connect to host
 dick.red: could not connect to host
 didierlaumen.be: could not connect to host
@@ -635,7 +635,6 @@ diz.in.ua: could not connect to host
 djul.net: could not connect to host
 dlouwrink.nl: could not connect to host
 dlyl888.com: could not connect to host
-dn3s.me: could not connect to host
 dna.li: could not connect to host
 dnfc.rocks: could not connect to host
 dnmaze.com: could not connect to host
@@ -651,6 +650,7 @@ domainoo.com: could not connect to host
 domengrad.ru: could not connect to host
 domfee.com: could not connect to host
 dongkexue.com: could not connect to host
+donovand.info: could not connect to host
 doopdidoop.com: could not connect to host
 dougferris.id.au: could not connect to host
 doyoulyft.com: could not connect to host
@@ -759,6 +759,7 @@ exceptionalservices.us: could not connect to host
 exo.do: could not connect to host
 exteriorservices.io: could not connect to host
 eytosh.net: could not connect to host
+eztvtorrent.com: could not connect to host
 f1bigpicture.com: could not connect to host
 f8842.com: could not connect to host
 faber.org.ru: could not connect to host
@@ -824,6 +825,7 @@ flow.su: could not connect to host
 flucky.xyz: could not connect to host
 flugplatz-edvc.de: could not connect to host
 flyingdoggy.net: could not connect to host
+flyingrub.me: could not connect to host
 focalforest.com: could not connect to host
 fojing.com: could not connect to host
 foodserve.in: could not connect to host
@@ -869,12 +871,10 @@ fun99.cc: could not connect to host
 funksteckdosen24.de: could not connect to host
 funoverip.net: could not connect to host
 funspins.com: could not connect to host
-furnishedproperty.com.au: could not connect to host
 futos.de: could not connect to host
 futuresonline.com: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsISiteSecurityService.processHeader]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: /builds/slave/m-cen-l64-periodicupdate-00000/getHSTSPreloadList.js :: processStsHeader :: line 116"  data: no]
 fuzoku-sodan.com: could not connect to host
 fyol.pw: could not connect to host
-fysiotherapierossum.nl: could not connect to host
 g01.in.ua: could not connect to host
 g1jeu.com: could not connect to host
 gaasuper6.com: could not connect to host
@@ -892,6 +892,7 @@ garage-door.pro: could not connect to host
 gasbarkenora.com: could not connect to host
 gasnews.net: could not connect to host
 gautham.pro: could not connect to host
+gay-jays.com: could not connect to host
 gayforgenji.com: could not connect to host
 gaygeeks.de: could not connect to host
 gc.net: could not connect to host
@@ -1024,6 +1025,7 @@ heavenlysmokenc.com: could not connect to host
 heisenberg.co: could not connect to host
 hejsupport.se: could not connect to host
 hellofilters.com: could not connect to host
+hellomouse.cf: could not connect to host
 hellomouse.tk: could not connect to host
 helpantiaging.com: could not connect to host
 helpekwendenihospital.com: could not connect to host
@@ -1068,6 +1070,7 @@ hozinga.de: could not connect to host
 hr98.tk: could not connect to host
 hserver.top: could not connect to host
 httptest.net: could not connect to host
+huangguancq.com: could not connect to host
 huangzenghao.cn: could not connect to host
 huangzenghao.com: could not connect to host
 hudingyuan.cn: could not connect to host
@@ -1079,7 +1082,6 @@ huongquynh.com: could not connect to host
 huwjones.me: could not connect to host
 huzurmetal.net: could not connect to host
 hydrante.ch: could not connect to host
-hydronyx.me: could not connect to host
 hyper-matrix.org: could not connect to host
 hyperactive.am: could not connect to host
 hypotecnicentrum.cz: could not connect to host
@@ -1092,6 +1094,7 @@ iamsoareyou.se: could not connect to host
 ibron.co: could not connect to host
 ibsafrica.co.za: could not connect to host
 ibsglobal.co.za: could not connect to host
+icasnetwork.com: could not connect to host
 iceloch.com: could not connect to host
 ictpro.info: could not connect to host
 icusignature.com: could not connect to host
@@ -1109,7 +1112,6 @@ igamingforums.com: could not connect to host
 ihatethissh.it: could not connect to host
 iideaz.org: could not connect to host
 iilin.com: could not connect to host
-iiong.com: could not connect to host
 iirii.com: could not connect to host
 ikenmeyer.com: could not connect to host
 ikenmeyer.eu: could not connect to host
@@ -1135,7 +1137,6 @@ inexpensivecomputers.net: could not connect to host
 informatik.zone: could not connect to host
 infoworm.org: could not connect to host
 infruction.com: could not connect to host
-injust.eu.org: could not connect to host
 injust.me: could not connect to host
 innovativebuildingsolutions.co.za: could not connect to host
 innovativeideaz.org: could not connect to host
@@ -1202,7 +1203,6 @@ jecho.cn: could not connect to host
 jeffersonregan.org: could not connect to host
 jens.hk: could not connect to host
 jerrypau.ca: could not connect to host
-jeva.nl: could not connect to host
 jhburton.co.uk: could not connect to host
 jiangzm.com: could not connect to host
 jianyuan.pro: could not connect to host
@@ -1216,7 +1216,6 @@ joetyson.io: could not connect to host
 johntomasowa.com: could not connect to host
 jonathansanchez.pro: could not connect to host
 jonfor.net: could not connect to host
-jonpads.com: could not connect to host
 jooto.com: could not connect to host
 josc.com.au: could not connect to host
 joshharkema.com: could not connect to host
@@ -1233,6 +1232,7 @@ just-pools.co.za: could not connect to host
 justinharrison.ca: could not connect to host
 justzz.xyz: could not connect to host
 juventusmania1897.com: could not connect to host
+jzbk.org: could not connect to host
 k33k00.com: could not connect to host
 kabus.org: could not connect to host
 kaika-facilitymanagement.de: could not connect to host
@@ -1251,12 +1251,12 @@ katyusha.net: could not connect to host
 kawaiiku.com: could not connect to host
 kawaiiku.de: could not connect to host
 kaydan.io: could not connect to host
+kb3.net: could not connect to host
 kearney.io: could not connect to host
 kellyandantony.com: could not connect to host
 kelm.me: could not connect to host
 kermadec.com: could not connect to host
 keshausconsulting.com: could not connect to host
-kevinbowers.me: could not connect to host
 kevindekoninck.com: could not connect to host
 kevinfoley.cc: could not connect to host
 kevinfoley.org: could not connect to host
@@ -1293,6 +1293,7 @@ kopfsalat.eu: could not connect to host
 koppelvlak.net: could not connect to host
 kotitesti.fi: could not connect to host
 kotorimusic.ga: could not connect to host
+kottur.is: could not connect to host
 kozmik.co: could not connect to host
 krag.be: could not connect to host
 krampus-fischamend.at: could not connect to host
@@ -1301,6 +1302,7 @@ ksero.center: could not connect to host
 ktube.yt: could not connect to host
 kubusadvocaten.nl: could not connect to host
 kuko-crews.org: could not connect to host
+kupiec.eu.org: could not connect to host
 kwikmed.eu: could not connect to host
 kwipi.com: could not connect to host
 kyberna.xyz: could not connect to host
@@ -1330,6 +1332,7 @@ latemodern.com: could not connect to host
 lathamlabs.com: could not connect to host
 lathamlabs.net: could not connect to host
 lathamlabs.org: could not connect to host
+lazerus.net: could not connect to host
 lazulu.com: could not connect to host
 lbarrios.es: could not connect to host
 lbrls.tk: could not connect to host
@@ -1352,7 +1355,6 @@ leifdreizler.com: could not connect to host
 lenkunz.me: could not connect to host
 leolana.com: could not connect to host
 leonardcamacho.me: could not connect to host
-leonhooijer.nl: could not connect to host
 lerlivros.online: could not connect to host
 lescomptoirsdepierrot.com: could not connect to host
 lesdouceursdeliyana.com: could not connect to host
@@ -1365,12 +1367,6 @@ lheinrich.org: could not connect to host
 lhsj28.com: could not connect to host
 lhsj68.com: could not connect to host
 lhsj78.com: could not connect to host
-lianye1.cc: could not connect to host
-lianye2.cc: could not connect to host
-lianye3.cc: could not connect to host
-lianye4.cc: could not connect to host
-lianye5.cc: could not connect to host
-lianye6.cc: could not connect to host
 liaozheqi.cn: could not connect to host
 libertas-tech.com: could not connect to host
 librisulibri.it: could not connect to host
@@ -1393,7 +1389,6 @@ lisieuxarquitetura.com.br: could not connect to host
 lissabon.guide: could not connect to host
 litcomphonors.com: could not connect to host
 littlelundgrenladies.com: could not connect to host
-litvideoserver.de: could not connect to host
 liukang.tech: could not connect to host
 llvm.us: could not connect to host
 loanstreet.be: could not connect to host
@@ -1403,7 +1398,6 @@ locker3.com: could not connect to host
 locksport.org.nz: could not connect to host
 logcat.info: could not connect to host
 logic8.ml: could not connect to host
-logicchen.com: could not connect to host
 logimagine.com: could not connect to host
 lolicon.eu: could not connect to host
 lookyman.net: could not connect to host
@@ -1439,7 +1433,6 @@ maartenterpstra.xyz: could not connect to host
 madeintucson.org: could not connect to host
 madnetwork.org: could not connect to host
 madusecurity.com: could not connect to host
-magicball.co: could not connect to host
 magnacumlaude.co: could not connect to host
 mahansexcavating.com: could not connect to host
 maik-mahlow.de: could not connect to host
@@ -1474,7 +1467,6 @@ mathijskingma.nl: could not connect to host
 matrix.ac: could not connect to host
 matthewtester.com: could not connect to host
 matthey.nl: could not connect to host
-max-moeglich.de: could not connect to host
 maybeul.com: could not connect to host
 maynardnetworks.com: could not connect to host
 mazternet.ru: could not connect to host
@@ -1490,7 +1482,6 @@ mckinley1.com: could not connect to host
 mcsa-usa.org: could not connect to host
 mcsnovatamabayan.com: could not connect to host
 me-dc.com: could not connect to host
-meadowfen.farm: could not connect to host
 meathealth.com: could not connect to host
 mecanicadom.com: could not connect to host
 mediadandy.com: could not connect to host
@@ -1509,24 +1500,22 @@ memepasmal.org: could not connect to host
 menchez.me: could not connect to host
 menzaijia.com: could not connect to host
 mercanix.co.uk: could not connect to host
-mes10doigts.ovh: could not connect to host
 metaether.net: could not connect to host
 metrix-money-ptc.com: could not connect to host
 metrix.design: could not connect to host
 mexior.nl: could not connect to host
 meyeraviation.com: could not connect to host
-mhjuma.com: could not connect to host
 michaelcullen.name: could not connect to host
 michaelkuchta.me: could not connect to host
 michaelsulzer.com: could not connect to host
 michaelsulzer.eu: could not connect to host
-michaelzomer.com: could not connect to host
 michasfahrschule.com: could not connect to host
 microblading.pe: could not connect to host
 microlinks.org: could not connect to host
 mieterschutzkartei.de: could not connect to host
 mikeybot.com: could not connect to host
 millionairessecrets.com: could not connect to host
+minantavla.se: could not connect to host
 mingy.ddns.net: could not connect to host
 mingyueli.com: could not connect to host
 minimaliston.com: could not connect to host
@@ -1536,7 +1525,6 @@ misconfigured.io: could not connect to host
 missycosmeticos.com.br: could not connect to host
 miyako-kyoto.jp: could not connect to host
 mkfs.fr: could not connect to host
-mkhsoft.eu: could not connect to host
 mkp-deutschland.de: could not connect to host
 mkplay.io: could not connect to host
 mmilog.hu: could not connect to host
@@ -1603,7 +1591,6 @@ my-dick.ru: could not connect to host
 my-dns.co.il: could not connect to host
 my-floor.com: could not connect to host
 mycamda.com: could not connect to host
-mycareersfuture.sg: could not connect to host
 myfappening.org: could not connect to host
 myfunworld.de: could not connect to host
 mygreatjob.eu: could not connect to host
@@ -1653,8 +1640,7 @@ nienfun.com: could not connect to host
 nikksno.io: could not connect to host
 nikobradshaw.com: could not connect to host
 nikolasbradshaw.com: could not connect to host
-ninreiei.jp: could not connect to host
-ninux.ch: could not connect to host
+ninofink.com: could not connect to host
 niouininon.eu: could not connect to host
 nirada.info: could not connect to host
 nishikino-maki.com: could not connect to host
@@ -1663,6 +1649,7 @@ nocs.cn: could not connect to host
 nodelab-it.de: could not connect to host
 nodeselect.com: could not connect to host
 noelblog.ga: could not connect to host
+noelssanssoucipensacola.com: could not connect to host
 noisebridge.social: could not connect to host
 nolimits.net.nz: could not connect to host
 nonemu.ninja: could not connect to host
@@ -1700,6 +1687,7 @@ olgui.net: could not connect to host
 oliverspringer.eu: could not connect to host
 oneazcu.com: could not connect to host
 onewebdev.info: could not connect to host
+onix.eu.com: could not connect to host
 onsennuie.fr: could not connect to host
 onsite4u.de: could not connect to host
 onstud.com: could not connect to host
@@ -1712,7 +1700,6 @@ orangekey.tk: could not connect to host
 oranges.tokyo: could not connect to host
 oranic.com: could not connect to host
 oricejoc.com: could not connect to host
-osacrypt.studio: could not connect to host
 oscarmashauri.com: could not connect to host
 oscsdp.cz: could not connect to host
 oshell.me: could not connect to host
@@ -1754,8 +1741,8 @@ pcvirusclear.com: could not connect to host
 pear2pear.de: could not connect to host
 peerless.ae: could not connect to host
 peirong.me: could not connect to host
-pelletizermill.com: could not connect to host
 pemagrid.org: could not connect to host
+pengi.me: could not connect to host
 pengisatelier.net: could not connect to host
 pepper.dog: could not connect to host
 persjrp.ca: could not connect to host
@@ -1772,6 +1759,7 @@ phillippi.me: could not connect to host
 photographyforchange.com: could not connect to host
 photographyforchange.org: could not connect to host
 photops.fr: could not connect to host
+photosoftware.nl: could not connect to host
 phuong.faith: could not connect to host
 pianetaottica.eu: could not connect to host
 pianetaottica.info: could not connect to host
@@ -1780,7 +1768,6 @@ picone.com.au: could not connect to host
 picotronic.de: could not connect to host
 picsandtours.com: could not connect to host
 pierrejeansuau.fr: could not connect to host
-pietawittermans.nl: could not connect to host
 pieterhordijk.com: could not connect to host
 pimspage.nl: could not connect to host
 pinebaylibrary.org: could not connect to host
@@ -1794,12 +1781,12 @@ plaasprodukte.com: could not connect to host
 planbox.info: could not connect to host
 planningexcellence.com.au: could not connect to host
 playsharp.com: could not connect to host
-playsource.co: could not connect to host
 please-deny.me: could not connect to host
 plexi.dyndns.tv: could not connect to host
 plussizereviews.com: could not connect to host
 pmbremer.de: could not connect to host
 pogs.us: could not connect to host
+pointagri.com: could not connect to host
 polit.im: could not connect to host
 pookl.com: could not connect to host
 poolinstallers.co.za: could not connect to host
@@ -1807,12 +1794,10 @@ popkins.cf: could not connect to host
 popkins.ga: could not connect to host
 popkins.gq: could not connect to host
 popkins.tk: could not connect to host
-pornbay.org: could not connect to host
 pornblog.org: could not connect to host
 porschen.fr: could not connect to host
 port.social: could not connect to host
 portalisapres.cl: could not connect to host
-posobota.cz: could not connect to host
 posters.win: could not connect to host
 potbar.com: could not connect to host
 potbox.com: could not connect to host
@@ -1865,7 +1850,6 @@ psyk.yt: could not connect to host
 publimepa.it: could not connect to host
 pugilares.com.pl: could not connect to host
 puhe.se: could not connect to host
-puikheid.nl: could not connect to host
 pwdgen.net: could not connect to host
 pwntr.com: could not connect to host
 pyjiaoyi.cf: could not connect to host
@@ -1887,8 +1871,10 @@ racasdecachorro.org: could not connect to host
 rackblue.com: could not connect to host
 radartatska.se: could not connect to host
 rainbin.com: could not connect to host
+randomquotesapp.com: could not connect to host
 rangsmo.se: could not connect to host
 ranos.org: could not connect to host
+raphrfg.com: could not connect to host
 ravengergaming.net: could not connect to host
 ravse.dk: could not connect to host
 raycarruthersphotography.co.uk: could not connect to host
@@ -1919,17 +1905,16 @@ reismil.ch: could not connect to host
 relatic.net: could not connect to host
 relsak.cz: could not connect to host
 renemayrhofer.com: could not connect to host
-rentbrowser.com: could not connect to host
 report-incident.de: could not connect to host
 reposaarenkuva.fi: could not connect to host
 reqognize.com: could not connect to host
 research.md: could not connect to host
 resoundpro.ca: could not connect to host
+restioson.me: could not connect to host
 reth.ch: could not connect to host
 retube.ga: could not connect to host
 reucon.com: could not connect to host
 reykjavik.guide: could not connect to host
-rhodes.ml: could not connect to host
 ribopierre.fr: could not connect to host
 riceglue.com: could not connect to host
 richardb.me: could not connect to host
@@ -1937,6 +1922,7 @@ richeza.com: [Exception... "Component returned failure code: 0x80004005 (NS_ERRO
 righteousendeavour.com: could not connect to host
 riversideauto.net: could not connect to host
 riverstyxgame.com: could not connect to host
+rmstudio.tw: could not connect to host
 roave.com: could not connect to host
 robi-net.it: could not connect to host
 robomonkey.org: could not connect to host
@@ -1965,11 +1951,10 @@ rtc.fun: could not connect to host
 rubbix.net: could not connect to host
 rubendv.be: could not connect to host
 ruhr3.de: could not connect to host
-ruja.dk: could not connect to host
+run-forrest.run: could not connect to host
 runcarina.com: could not connect to host
 rundumcolumn.xyz: could not connect to host
-runschrauger.com: could not connect to host
-ruobr.ru: could not connect to host
+rushball.net: could not connect to host
 ruurdboomsma.nl: could not connect to host
 rzegroup.com: could not connect to host
 s0923.com: could not connect to host
@@ -1979,7 +1964,6 @@ safedevice.net: could not connect to host
 safejourney.education: could not connect to host
 saferedirectlink.com: could not connect to host
 sagemontchurch.org: could not connect to host
-sahkotyot.eu: could not connect to host
 sallysubs.com: could not connect to host
 salzamt.tk: could not connect to host
 samaritan.tech: could not connect to host
@@ -2004,19 +1988,12 @@ scalaire.fr: could not connect to host
 schaafenstrasse.koeln: could not connect to host
 schmidttulskie.de: could not connect to host
 schnapke.name: could not connect to host
-schrauger.com: could not connect to host
-schrauger.info: could not connect to host
-schrauger.net: could not connect to host
-schrauger.org: could not connect to host
-schrauger.run: could not connect to host
-schraugerrun.com: could not connect to host
 schul-bar.de: could not connect to host
 scib.tk: could not connect to host
 sciencemonster.co.uk: could not connect to host
 scintillating.stream: could not connect to host
 scitopia.me: could not connect to host
 scm-2017.org: could not connect to host
-scootfleet.com: could not connect to host
 scottainslie.me.uk: could not connect to host
 scripthost.org: could not connect to host
 scriptjunkie.us: could not connect to host
@@ -2036,7 +2013,6 @@ securitysoapbox.com: could not connect to host
 securitytalk.pl: could not connect to host
 securon.io: could not connect to host
 securoswiss.ch: could not connect to host
-seeclop.ch: could not connect to host
 seefirm.com: could not connect to host
 seen.life: could not connect to host
 selent.me: could not connect to host
@@ -2083,7 +2059,6 @@ sikatehtaat.fi: could not connect to host
 siku.pro: could not connect to host
 silqueskineyeserum.com: could not connect to host
 silverback.is: could not connect to host
-silviamacallister.com: could not connect to host
 silvistefi.com: could not connect to host
 simhaf.cf: could not connect to host
 simonschmitt.ch: could not connect to host
@@ -2163,10 +2138,6 @@ staticisnoise.com: could not connect to host
 statusbot.io: could not connect to host
 steffi-in-australien.com: could not connect to host
 stellarium-gornergrat.ch: could not connect to host
-stephenschrauger.com: could not connect to host
-stephenschrauger.info: could not connect to host
-stephenschrauger.net: could not connect to host
-stephenschrauger.org: could not connect to host
 stevengoodpaster.com: could not connect to host
 stickswag.cf: could not connect to host
 stikonas.eu: could not connect to host
@@ -2177,10 +2148,8 @@ stonemanbrasil.com.br: could not connect to host
 stopakwardhandshakes.org: could not connect to host
 store10.de: could not connect to host
 stpip.com: could not connect to host
-streamer.tips: could not connect to host
 streams.dyndns.org: could not connect to host
 stressfreehousehold.com: could not connect to host
-sturge.co.uk: could not connect to host
 stylle.me: could not connect to host
 subrain.com: could not connect to host
 sudo.im: could not connect to host
@@ -2218,8 +2187,6 @@ syncmylife.net: could not connect to host
 synergisticsoccer.com: could not connect to host
 sysert.tv: could not connect to host
 system12.pl: could not connect to host
-systematic-momo.com: could not connect to host
-systematic-momo.dk: could not connect to host
 szunia.com: could not connect to host
 t3rror.net: could not connect to host
 tab.watch: could not connect to host
@@ -2257,13 +2224,11 @@ terra-x.net: could not connect to host
 terrax.net: could not connect to host
 testadron.com: could not connect to host
 testovaci.ml: could not connect to host
-texy.info: could not connect to host
 tgod.co: could not connect to host
 tgtv.tn: could not connect to host
 thai.land: could not connect to host
 thaigirls.xyz: could not connect to host
 thatgudstuff.com: could not connect to host
-the-digitale.com: could not connect to host
 the-earth-yui.net: could not connect to host
 the-finance-blog.com: could not connect to host
 the-gist.io: could not connect to host
@@ -2282,6 +2247,7 @@ theprincegame.com: could not connect to host
 theprivacysolution.com: could not connect to host
 thequillmagazine.org: could not connect to host
 thermique.ch: could not connect to host
+thesecondsposts.com: could not connect to host
 thesehighsandlows.com: could not connect to host
 theserver201.tk: could not connect to host
 thetapirsmouth.com: could not connect to host
@@ -2337,6 +2303,7 @@ transappealrights.com: could not connect to host
 transcendmotor.sg: could not connect to host
 transmithe.net: could not connect to host
 travotion.com: could not connect to host
+tree0.xyz: could not connect to host
 treker.us: could not connect to host
 triageo.com.au: could not connect to host
 tristanfarkas.one: could not connect to host
@@ -2402,6 +2369,7 @@ valecnatechnika.cz: could not connect to host
 valenhub.com: could not connect to host
 valenhub.es: could not connect to host
 valis.sx: could not connect to host
+valkor.pro: could not connect to host
 vamosfalardesaude.pt: could not connect to host
 vanderstraeten.dynv6.net: could not connect to host
 vapemania.eu: could not connect to host
@@ -2410,7 +2378,6 @@ variable.agency: could not connect to host
 vayaport.com: could not connect to host
 vconcept.ch: could not connect to host
 vconcept.me: could not connect to host
-vdanker.net: could not connect to host
 vectro.me: could not connect to host
 velasense.com: could not connect to host
 velen.io: could not connect to host
@@ -2430,7 +2397,6 @@ villasenor.online: could not connect to host
 vimeosucks.nyc: could not connect to host
 vinesauce.info: could not connect to host
 vinetalk.net: could not connect to host
-vinogradovka.com: could not connect to host
 viosey.com: could not connect to host
 vipnettikasinoklubi.com: could not connect to host
 visiongamestudios.com: could not connect to host
@@ -2470,6 +2436,7 @@ wanda98.com: could not connect to host
 warcraftjournal.org: could not connect to host
 warlions.info: could not connect to host
 warp-radio.com: could not connect to host
+warp-radio.tv: could not connect to host
 wassim.is: could not connect to host
 watashi.bid: could not connect to host
 watchstyle.com: could not connect to host
@@ -2478,7 +2445,6 @@ waxdramatic.com: could not connect to host
 we.serveftp.net: could not connect to host
 weareincognito.org: could not connect to host
 webart-factory.de: could not connect to host
-webbson.net: could not connect to host
 webhackspro.com: could not connect to host
 webnetmail4u.com: could not connect to host
 webproject.rocks: could not connect to host
@@ -2534,7 +2500,6 @@ workemy.com: could not connect to host
 workwithgo.com: could not connect to host
 worldfree4.org: could not connect to host
 wormholevpn.net: could not connect to host
-wowhelp.it: could not connect to host
 wp-fastsearch.de: could not connect to host
 wp-stack.pro: could not connect to host
 wp6.pw: could not connect to host
@@ -2563,6 +2528,7 @@ xn--t8j2a3042d.xyz: could not connect to host
 xn--tda.ml: could not connect to host
 xn--thorme-6uaf.ca: could not connect to host
 xn--vck8crc010pu14e.biz: could not connect to host
+xn--y8j2eb5631a4qf5n0h.com: could not connect to host
 xn--yj8h0m.ws: could not connect to host
 xn--ykrp42k.com: could not connect to host
 xpwn.cz: could not connect to host
@@ -2576,7 +2542,6 @@ yabrt.cn: could not connect to host
 yahoo.ax: could not connect to host
 yarchives.jp: could not connect to host
 yaucy.win: could not connect to host
-ybresson.com: could not connect to host
 yd.io: could not connect to host
 yellowcar.website: could not connect to host
 yemalu.com: could not connect to host
@@ -2598,7 +2563,6 @@ yoticonnections.com: could not connect to host
 yotilabs.com: could not connect to host
 yourznc.com: could not connect to host
 yousite.by: could not connect to host
-yoyoost.duckdns.org: could not connect to host
 yude.ml: could not connect to host
 yum.beer: could not connect to host
 yux.fr: could not connect to host
@@ -2608,9 +2572,9 @@ zachbolinger.com: could not connect to host
 zaoext.com: could not connect to host
 zbchen.com: could not connect to host
 zbp.at: could not connect to host
-zeitzer-turngala.de: could not connect to host
 zeloz.xyz: could not connect to host
 zenghx.tk: could not connect to host
+zenlogic.com: could not connect to host
 zero-x-baadf00d.com: could not connect to host
 zerocool.io: could not connect to host
 zerosource.net: could not connect to host
@@ -2625,14 +2589,10 @@ zmk.fr: could not connect to host
 zobraz.cz: could not connect to host
 zohar.shop: could not connect to host
 zokster.net: could not connect to host
-zolokar.xyz: could not connect to host
 zonemaster.fr: could not connect to host
-zonemaster.net: could not connect to host
-zoological-gardens.eu: could not connect to host
 zorz.info: could not connect to host
 zudomc.me: could not connect to host
 zuehlcke.de: could not connect to host
-zulu7.com: could not connect to host
 zuviel.space: could not connect to host
 zypr.pw: could not connect to host
 zyx.im: could not connect to host
@@ -2643,7 +2603,7 @@ zzw.ca: could not connect to host
 0005aa.com: could not connect to host
 007sascha.de: did not receive HSTS header
 020wifi.nl: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsISiteSecurityService.processHeader]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: /builds/slave/m-cen-l64-periodicupdate-00000/getHSTSPreloadList.js :: processStsHeader :: line 116"  data: no]
-0222aa.com: did not receive HSTS header
+0222aa.com: could not connect to host
 02dl.net: did not receive HSTS header
 040fit.nl: did not receive HSTS header
 048.ag: could not connect to host
@@ -2681,8 +2641,6 @@ zzw.ca: could not connect to host
 127011-networks.ch: did not receive HSTS header
 12vpn.org: could not connect to host
 12vpnchina.com: could not connect to host
-1391kj.com: did not receive HSTS header
-1395kj.com: did not receive HSTS header
 1396.cc: did not receive HSTS header
 1536.cf: could not connect to host
 163pwd.com: could not connect to host
@@ -2695,7 +2653,6 @@ zzw.ca: could not connect to host
 188trafalgar.ca: did not receive HSTS header
 195gm.com: could not connect to host
 1a-jva.de: could not connect to host
-1a-werkstattgeraete.de: did not receive HSTS header
 1atic.com: could not connect to host
 1co-jp.net: did not receive HSTS header
 1cover.com: could not connect to host
@@ -2866,6 +2823,7 @@ access-sofia.org: did not receive HSTS header
 accommodation-berry.com.au: max-age too low: 300
 accountradar.com: max-age too low: 86400
 accounts-p.com: could not connect to host
+aceadvisory.biz: did not receive HSTS header
 acgmoon.org: did not receive HSTS header
 acheirj.com.br: could not connect to host
 acheritage.co.uk: did not receive HSTS header
@@ -2947,6 +2905,7 @@ agatheetraphael.fr: could not connect to host
 agbremen.de: did not receive HSTS header
 agentseeker.ca: could not connect to host
 agevio.com: could not connect to host
+agonswim.com: did not receive HSTS header
 agrias.com.br: did not receive HSTS header
 agrimap.com: did not receive HSTS header
 agro-id.gov.ua: did not receive HSTS header
@@ -2985,7 +2944,7 @@ akselimedia.fi: did not receive HSTS header
 akstudentsfirst.org: could not connect to host
 aktivist.in: did not receive HSTS header
 al-shami.net: could not connect to host
-alair.cn: could not connect to host
+alair.cn: did not receive HSTS header
 alanlee.net: could not connect to host
 alanrickmanflipstable.com: could not connect to host
 alariel.de: did not receive HSTS header
@@ -3139,7 +3098,6 @@ annahmeschluss.de: did not receive HSTS header
 annarbor.group: did not receive HSTS header
 annsbouncycastles.com: did not receive HSTS header
 anomaly.ws: did not receive HSTS header
-anonboards.com: did not receive HSTS header
 anonymo.co.uk: could not connect to host
 anonymo.uk: could not connect to host
 anonymousstatecollegelulzsec.com: could not connect to host
@@ -3178,6 +3136,7 @@ aperture-laboratories.science: did not receive HSTS header
 api.mega.co.nz: could not connect to host
 apibot.de: could not connect to host
 apis.world: could not connect to host
+apl2bits.net: did not receive HSTS header
 apmg-certified.com: did not receive HSTS header
 apmg-cyber.com: did not receive HSTS header
 apnakliyat.com: did not receive HSTS header
@@ -3201,6 +3160,7 @@ apps-for-fishing.com: could not connect to host
 appsbystudio.co.uk: did not receive HSTS header
 appsdash.io: could not connect to host
 appuro.com: did not receive HSTS header
+appzoojoo.be: did not receive HSTS header
 aquariumaccessories.shop: did not receive HSTS header
 aquilalab.com: could not connect to host
 arabdigitalexpression.org: did not receive HSTS header
@@ -3244,7 +3204,6 @@ arrowfunction.com: could not connect to host
 ars-design.net: could not connect to host
 art2web.net: could not connect to host
 artartefatos.com.br: could not connect to host
-artbytik.ru: did not receive HSTS header
 artegusto.ru: did not receive HSTS header
 arterienundvenen.ch: did not receive HSTS header
 artesupra.com: did not receive HSTS header
@@ -3337,6 +3296,7 @@ authoritynutrition.com: did not receive HSTS header
 auto-serwis.zgorzelec.pl: could not connect to host
 auto3d.cn: could not connect to host
 auto4trade.nl: could not connect to host
+autoauctionsvirginia.com: did not receive HSTS header
 autobedarf.net: did not receive HSTS header
 autodeploy.it: could not connect to host
 autoecolebudget.ch: did not receive HSTS header
@@ -3573,7 +3533,6 @@ biaoqingfuhao.net: did not receive HSTS header
 biaoqingfuhao.org: did not receive HSTS header
 biapinheiro.com.br: max-age too low: 5184000
 biblerhymes.com: did not receive HSTS header
-bichines.es: did not receive HSTS header
 bidon.ca: did not receive HSTS header
 bieberium.de: could not connect to host
 biego.cn: did not receive HSTS header
@@ -3637,7 +3596,6 @@ bitrage.de: could not connect to host
 bitraum.io: could not connect to host
 bitsafe.systems: did not receive HSTS header
 bitvigor.com: could not connect to host
-bitwrought.net: could not connect to host
 bivsi.com: could not connect to host
 bizcms.com: did not receive HSTS header
 bizon.sk: did not receive HSTS header
@@ -3730,7 +3688,7 @@ bootikexpress.fr: did not receive HSTS header
 borderlinegroup.com: could not connect to host
 boringsecurity.net: could not connect to host
 boris.one: did not receive HSTS header
-borisavstankovic.rs: could not connect to host
+borisavstankovic.rs: did not receive HSTS header
 borrelioz.com: did not receive HSTS header
 borscheid-wenig.com: did not receive HSTS header
 boschee.net: could not connect to host
@@ -3813,6 +3771,7 @@ bubulazy.com: did not receive HSTS header
 buch-cuber.de: max-age too low: 0
 buchheld.at: did not receive HSTS header
 bucket.tk: could not connect to host
+buckmulligans.com: did not receive HSTS header
 budgetthostels.nl: did not receive HSTS header
 budskap.eu: did not receive HSTS header
 buenosairesestetica.com.ar: could not connect to host
@@ -3897,6 +3856,7 @@ bypro.xyz: could not connect to host
 bysymphony.com: max-age too low: 0
 byte.chat: did not receive HSTS header
 byte.wtf: did not receive HSTS header
+byte128.com: did not receive HSTS header
 bytesatwork.eu: could not connect to host
 bytesund.biz: could not connect to host
 byurudraw.pics: could not connect to host
@@ -3906,6 +3866,7 @@ c2lab.net: did not receive HSTS header
 c3-compose.com: could not connect to host
 c3b.info: could not connect to host
 c3ie.com: did not receive HSTS header
+ca-terminal-multiservices.fr: did not receive HSTS header
 cabsites.com: could not connect to host
 cabusar.fr: did not receive HSTS header
 caconnect.org: could not connect to host
@@ -4001,7 +3962,6 @@ cavedevs.de: could not connect to host
 cavedroid.xyz: could not connect to host
 cavern.tv: did not receive HSTS header
 cayafashion.de: did not receive HSTS header
-cayounglab.co.jp: did not receive HSTS header
 cbengineeringinc.com: max-age too low: 86400
 cbhq.net: could not connect to host
 ccblog.de: did not receive HSTS header
@@ -4038,7 +3998,6 @@ cevrimici.com: could not connect to host
 cfcnexus.org: could not connect to host
 cfcproperties.com: did not receive HSTS header
 cfetengineering.com: could not connect to host
-cfo.gov: did not receive HSTS header
 cfoitplaybook.com: could not connect to host
 cganx.org: could not connect to host
 cgerstner.eu: did not receive HSTS header
@@ -4053,7 +4012,7 @@ changetip.com: did not receive HSTS header
 channyc.com: did not receive HSTS header
 chanshiyu.com: did not receive HSTS header
 chaos.fail: could not connect to host
-chaoswebs.net: did not receive HSTS header
+chaoswebs.net: could not connect to host
 charityclear.com: did not receive HSTS header
 charitystreet.co.uk: could not connect to host
 charliemcneive.com: did not receive HSTS header
@@ -4107,7 +4066,7 @@ chrisbrown.id.au: could not connect to host
 chrisfaber.com: could not connect to host
 chriskirchner.de: did not receive HSTS header
 chriskyrouac.com: could not connect to host
-chrisopperwall.com: could not connect to host
+chrisopperwall.com: did not receive HSTS header
 chrisself.xyz: could not connect to host
 christiaandruif.nl: could not connect to host
 christianbro.gq: could not connect to host
@@ -4203,6 +4162,7 @@ clounix.online: could not connect to host
 clovissantos.com: could not connect to host
 clowde.in: could not connect to host
 clownaroundbouncycastles.co.uk: did not receive HSTS header
+clsimplex.com: did not receive HSTS header
 club-adulti.ro: did not receive HSTS header
 clubalfa.it: did not receive HSTS header
 clubcall.com: did not receive HSTS header
@@ -4316,8 +4276,6 @@ consciousbranding.org.au: could not connect to host
 consciousbrands.net.au: could not connect to host
 console.python.org: did not receive HSTS header
 console.support: did not receive HSTS header
-consultorcr.net: could not connect to host
-consumerfiles.com: did not receive HSTS header
 contactbig.com: did not receive HSTS header
 contaimo.com: did not receive HSTS header
 container-lion.com: did not receive HSTS header
@@ -4341,6 +4299,7 @@ cor-ser.es: could not connect to host
 coralproject.net: did not receive HSTS header
 coralrosado.com.br: did not receive HSTS header
 coramcdaniel.com: did not receive HSTS header
+corbax.com: did not receive HSTS header
 corderoscleaning.com: did not receive HSTS header
 cordial-restaurant.com: did not receive HSTS header
 core.mx: could not connect to host
@@ -4362,6 +4321,7 @@ correctpaardbatterijnietje.nl: did not receive HSTS header
 corruption-mc.net: could not connect to host
 corruption-rsps.net: could not connect to host
 corruption-server.net: could not connect to host
+cosmeticasimple.com: did not receive HSTS header
 cosmoluziluminacion.com: did not receive HSTS header
 costow.club: could not connect to host
 coughlan.de: did not receive HSTS header
@@ -4380,7 +4340,6 @@ crackingking.com: did not receive HSTS header
 craftbeerbarn.co.uk: could not connect to host
 craftedge.xyz: could not connect to host
 craftmain.eu: could not connect to host
-cranems.com.ua: could not connect to host
 cranioschule.com: did not receive HSTS header
 crate.io: did not receive HSTS header
 cravelyrics.com: could not connect to host
@@ -4427,6 +4386,7 @@ cryptojar.io: did not receive HSTS header
 cryptolab.pro: could not connect to host
 cryptolab.tk: could not connect to host
 cryptopartyatx.org: could not connect to host
+cryptophobia.nl: did not receive HSTS header
 cryptopush.com: did not receive HSTS header
 crysadm.com: could not connect to host
 crystalclassics.co.uk: did not receive HSTS header
@@ -4590,7 +4550,7 @@ dctxf.com: did not receive HSTS header
 dcuofriends.net: could not connect to host
 dcurt.is: did not receive HSTS header
 dcw.io: did not receive HSTS header
-ddatsh.com: did not receive HSTS header
+ddatsh.com: could not connect to host
 deadsoul.net: max-age too low: 0
 debank.tv: did not receive HSTS header
 debatch.se: could not connect to host
@@ -4680,10 +4640,11 @@ devlux.ch: did not receive HSTS header
 devmsg.com: did not receive HSTS header
 devnsec.com: could not connect to host
 devnull.team: could not connect to host
-devopps.me: could not connect to host
+devopps.me: did not receive HSTS header
 devopsconnected.com: could not connect to host
 devtub.com: did not receive HSTS header
 devuan.org: did not receive HSTS header
+dewebwerf.nl: did not receive HSTS header
 dewin.io: could not connect to host
 dfnet.ml: did not receive HSTS header
 dfrance.com.br: did not receive HSTS header
@@ -4873,7 +4834,6 @@ drinknaturespower.com: could not connect to host
 drinkvabeer.com: could not connect to host
 drishti.guru: could not connect to host
 drivercopilot.com: could not connect to host
-drkmtrx.xyz: did not receive HSTS header
 drlazarina.net: did not receive HSTS header
 droidboss.com: did not receive HSTS header
 droncentrum.pl: could not connect to host
@@ -4912,7 +4872,6 @@ dunea.nl: did not receive HSTS header
 duole30.com: did not receive HSTS header
 duongpho.com: did not receive HSTS header
 duskopy.top: could not connect to host
-dutchessuganda.com: did not receive HSTS header
 dutchrank.com: did not receive HSTS header
 duuu.ch: could not connect to host
 duyao.de: max-age too low: 86400
@@ -4941,7 +4900,6 @@ eagle-aluminum.com: did not receive HSTS header
 eam-gmbh.com: did not receive HSTS header
 earga.sm: could not connect to host
 earlybirdsnacks.com: could not connect to host
-earmarks.gov: did not receive HSTS header
 earthrise16.com: could not connect to host
 easthokkaido-5airport.jp: did not receive HSTS header
 easychiller.org: could not connect to host
@@ -5026,7 +4984,7 @@ ehito.ovh: could not connect to host
 ehrenamt-skpfcw.de: could not connect to host
 eicfood.com: could not connect to host
 eidolonhost.com: did not receive HSTS header
-eifelindex.de: could not connect to host
+eifelindex.de: did not receive HSTS header
 eigo.work: could not connect to host
 eimanavicius.lt: did not receive HSTS header
 ekbanden.nl: could not connect to host
@@ -5071,7 +5029,7 @@ email2rss.net: could not connect to host
 emanatepixels.com: could not connect to host
 emanga.su: did not receive HSTS header
 embroidered-stuff.com: could not connect to host
-emeldi-commerce.com: could not connect to host
+emeldi-commerce.com: max-age too low: 0
 emesolutions.net: did not receive HSTS header
 emiele.com.br: could not connect to host
 emilyhorsman.com: did not receive HSTS header
@@ -5243,7 +5201,7 @@ evilnerd.de: did not receive HSTS header
 evilsay.com: could not connect to host
 evin.ml: could not connect to host
 evites.me: could not connect to host
-evoludis.net: could not connect to host
+evoludis.net: did not receive HSTS header
 evomon.com: could not connect to host
 evossd.tk: could not connect to host
 evowl.com: could not connect to host
@@ -5390,7 +5348,7 @@ fikt.space: could not connect to host
 filebox.moe: could not connect to host
 filemeal.com: did not receive HSTS header
 filey.co.uk: did not receive HSTS header
-filidorwiese.nl: did not receive HSTS header
+fillmysuitca.se: did not receive HSTS header
 filmesubtitrate2017.online: could not connect to host
 filo.xyz: did not receive HSTS header
 filoitoupediou.gr: did not receive HSTS header
@@ -5659,6 +5617,7 @@ galletasgabi.com.mx: max-age too low: 86400
 galoisvpn.xyz: could not connect to host
 gambitcloud.net: could not connect to host
 game.yt: did not receive HSTS header
+gamebits.net: did not receive HSTS header
 gamecave.de: could not connect to host
 gamechasm.com: could not connect to host
 gameclue.jp: did not receive HSTS header
@@ -5802,7 +5761,6 @@ gizzo.sk: could not connect to host
 glasslikes.com: did not receive HSTS header
 glbg.eu: did not receive HSTS header
 glentakahashi.com: could not connect to host
-glittersjabloon.nl: did not receive HSTS header
 glitzmirror.com: could not connect to host
 globalado.com: could not connect to host
 globalbridge-japan.com: did not receive HSTS header
@@ -5815,7 +5773,6 @@ glotter.com: did not receive HSTS header
 gloucesterphotographer.com: did not receive HSTS header
 glubbforum.de: did not receive HSTS header
 glws.org: did not receive HSTS header
-gm-assicurazioni.it: did not receive HSTS header
 gmat.ovh: could not connect to host
 gmoes.at: could not connect to host
 go.ax: did not receive HSTS header
@@ -5858,6 +5815,7 @@ gopokego.cz: could not connect to host
 gorgiaxx.com: could not connect to host
 gorilla-gym.site: could not connect to host
 gorillow.com: could not connect to host
+gosharewood.com: did not receive HSTS header
 goshop.cz: did not receive HSTS header
 gostream.asia: could not connect to host
 gotgenes.com: could not connect to host
@@ -5885,7 +5843,6 @@ gracesofgrief.com: could not connect to host
 grachtenpandverkopen.nl: could not connect to host
 grafitec.ru: did not receive HSTS header
 grana.com: did not receive HSTS header
-grandefratellonews.com: could not connect to host
 grandlinecsk.ru: did not receive HSTS header
 grandmascookieblog.com: did not receive HSTS header
 grantedby.me: max-age too low: 0
@@ -5913,7 +5870,7 @@ greenvpn.pro: did not receive HSTS header
 gregorytlee.me: could not connect to host
 grekland.guide: could not connect to host
 gremots.com: could not connect to host
-grendel.no: did not receive HSTS header
+grendel.no: could not connect to host
 greplin.com: could not connect to host
 gresb.com: did not receive HSTS header
 gretchelizartistry.com: did not receive HSTS header
@@ -6000,7 +5957,6 @@ habbotalk.nl: could not connect to host
 hablemosdetecnologia.com.ve: could not connect to host
 hac30.com: could not connect to host
 hack.li: could not connect to host
-hackanders.com: did not receive HSTS header
 hacker8.cn: did not receive HSTS header
 hackercat.ninja: did not receive HSTS header
 hackerco.com: did not receive HSTS header
@@ -6110,7 +6066,7 @@ hcs-company.com: did not receive HSTS header
 hcs-company.nl: did not receive HSTS header
 hdrboundless.com: could not connect to host
 hdritalyphotos.com: did not receive HSTS header
-hdserver.info: did not receive HSTS header
+hdserver.info: could not connect to host
 hdsmigrationtool.com: could not connect to host
 hduin.xyz: could not connect to host
 head-shop.lt: could not connect to host
@@ -6267,7 +6223,7 @@ howrandom.org: could not connect to host
 howtocuremysciatica.com: could not connect to host
 hpepub.asia: could not connect to host
 hpepub.com: did not receive HSTS header
-hpepub.org: did not receive HSTS header
+hpepub.org: could not connect to host
 hppub.info: could not connect to host
 hppub.org: could not connect to host
 hppub.site: could not connect to host
@@ -6439,7 +6395,7 @@ inbox.li: did not receive HSTS header
 incendiary-arts.com: could not connect to host
 inche-ali.com: did not receive HSTS header
 inchomatic.com: did not receive HSTS header
-inderagamono.net: did not receive HSTS header
+inderagamono.net: could not connect to host
 indiecert.net: could not connect to host
 indiemods.com: could not connect to host
 indien.guide: could not connect to host
@@ -6535,7 +6491,6 @@ invictusmc.uk: could not connect to host
 invinsec.cloud: did not receive HSTS header
 inviosolutions.com: max-age too low: 0
 invite24.pro: could not connect to host
-invitethemhome.com: did not receive HSTS header
 iodice.org: did not receive HSTS header
 iolife.dk: could not connect to host
 ionas-law.ro: did not receive HSTS header
@@ -6549,6 +6504,7 @@ ipbill.org.uk: could not connect to host
 ipfp.pl: did not receive HSTS header
 iplife.cn: could not connect to host
 ipmimagazine.com: did not receive HSTS header
+ipo-times.com: did not receive HSTS header
 iprice.co.id: did not receive HSTS header
 iprice.hk: did not receive HSTS header
 iprice.my: did not receive HSTS header
@@ -6569,8 +6525,9 @@ iranianlawschool.com: could not connect to host
 iraqidinar.org: did not receive HSTS header
 irazimina.ru: did not receive HSTS header
 irccloud.com: did not receive HSTS header
+ircmett.de: did not receive HSTS header
 irelandesign.com: could not connect to host
-irisdina.de: did not receive HSTS header
+irisdina.de: could not connect to host
 irland.guide: could not connect to host
 irmtrudjurke.de: did not receive HSTS header
 irstaxforumsonline.com: did not receive HSTS header
@@ -6602,7 +6559,6 @@ istaspirtslietas.lv: did not receive HSTS header
 it-cave.com: could not connect to host
 it-go.net: did not receive HSTS header
 it-schwerin.de: could not connect to host
-itdashboard.gov: did not receive HSTS header
 itechgeek.com: max-age too low: 0
 items.lv: did not receive HSTS header
 itemton.com: could not connect to host
@@ -6610,6 +6566,7 @@ itfaq.nl: did not receive HSTS header
 itfensi.net: did not receive HSTS header
 ithakama.com: did not receive HSTS header
 ithakama.cz: did not receive HSTS header
+itilo.de: did not receive HSTS header
 itinsight.hu: did not receive HSTS header
 itos.asia: did not receive HSTS header
 itos.pl: did not receive HSTS header
@@ -6746,7 +6703,6 @@ jesuisformidable.nl: could not connect to host
 jesuslucas.com: did not receive HSTS header
 jet-code.com: could not connect to host
 jetaprices.com: max-age too low: 0
-jetflex.de: did not receive HSTS header
 jetlagphotography.com: could not connect to host
 jeton.com: did not receive HSTS header
 jetsetcharge.com: could not connect to host
@@ -6762,7 +6718,7 @@ jhejderup.me: could not connect to host
 jia1hao.com: could not connect to host
 jiaidu.com: could not connect to host
 jiangzequn.com: could not connect to host
-jianjiantv.com: did not receive HSTS header
+jianjiantv.com: could not connect to host
 jichi.me: could not connect to host
 jief.me: did not receive HSTS header
 jikken.de: could not connect to host
@@ -6775,6 +6731,7 @@ jimmycn.com: could not connect to host
 jingyuesi.com: could not connect to host
 jinmaguoji.com: could not connect to host
 jinshavip.com: could not connect to host
+jiosongs.com: did not receive HSTS header
 jira.com: did not receive HSTS header
 jirav.io: could not connect to host
 jisaku-homepage.com: did not receive HSTS header
@@ -6845,6 +6802,7 @@ jsg-technologies.de: did not receive HSTS header
 jualautoclave.com: did not receive HSTS header
 jualssh.com: could not connect to host
 juandesouza.com: did not receive HSTS header
+juiced.gs: did not receive HSTS header
 juka.pp.ua: could not connect to host
 juliamweber.de: could not connect to host
 julian-kipka.de: did not receive HSTS header
@@ -6872,7 +6830,7 @@ justnaw.co.uk: could not connect to host
 justudin.com: did not receive HSTS header
 justwood.cz: did not receive HSTS header
 jutella.de: did not receive HSTS header
-juul.xyz: did not receive HSTS header
+juul.xyz: could not connect to host
 juvenex.co: could not connect to host
 juwairen.cn: could not connect to host
 jvoice.net: could not connect to host
@@ -6964,6 +6922,7 @@ kermadec.blog: could not connect to host
 kermadec.net: could not connect to host
 kernl.us: did not receive HSTS header
 keskeces.com: did not receive HSTS header
+kevinbowers.me: did not receive HSTS header
 kevinbusse.de: did not receive HSTS header
 kevinroebert.de: did not receive HSTS header
 keymaster.lookout.com: did not receive HSTS header
@@ -6971,7 +6930,7 @@ kfbrussels.be: could not connect to host
 kg-rating.com: could not connect to host
 kgxtech.com: max-age too low: 2592000
 khaganat.net: did not receive HSTS header
-ki-on.net: could not connect to host
+ki-on.net: did not receive HSTS header
 kialo.com: did not receive HSTS header
 kickass-proxies.org: could not connect to host
 kickass.al: could not connect to host
@@ -7027,7 +6986,6 @@ kiwiirc.com: max-age too low: 5256000
 kiyo.space: could not connect to host
 kizil.net: could not connect to host
 kj1391.com: did not receive HSTS header
-kj1397.com: did not receive HSTS header
 kjaermaxi.me: did not receive HSTS header
 kjg-bachrain.de: could not connect to host
 klas.or.id: did not receive HSTS header
@@ -7145,6 +7103,7 @@ kzjnet.com: could not connect to host
 l-rickroll-i.pw: could not connect to host
 la-flora-negra.de: could not connect to host
 la-grande-jaugue.fr: did not receive HSTS header
+la-maison.eu: did not receive HSTS header
 la-retraite-info.com: did not receive HSTS header
 la-serendipite.fr: did not receive HSTS header
 labaia.info: could not connect to host
@@ -7170,6 +7129,7 @@ laf.in.net: could not connect to host
 lagalerievirtuelle.fr: did not receive HSTS header
 lagier.xyz: could not connect to host
 lagoza.name: could not connect to host
+laguinguette.fr: did not receive HSTS header
 lainchan.org: did not receive HSTS header
 laisashop.com.br: could not connect to host
 lamaland.ru: did not receive HSTS header
@@ -7265,6 +7225,7 @@ leonmahler.consulting: did not receive HSTS header
 leopold.email: could not connect to host
 leopotamgroup.com: could not connect to host
 lepont.pl: could not connect to host
+leponton-lorient.fr: did not receive HSTS header
 leppis-it.de: did not receive HSTS header
 lerasenglish.com: max-age too low: 0
 lerner.moscow: did not receive HSTS header
@@ -7356,6 +7317,7 @@ linuxforyou.com: could not connect to host
 linuxgeek.ro: could not connect to host
 linuxmint.cz: could not connect to host
 linuxmonitoring.net: did not receive HSTS header
+lipo.lol: did not receive HSTS header
 liquid.solutions: did not receive HSTS header
 liquorsanthe.in: could not connect to host
 lisaco.de: could not connect to host
@@ -7428,7 +7390,7 @@ lostinsecurity.com: could not connect to host
 lostinweb.eu: could not connect to host
 lothai.re: did not receive HSTS header
 lothuytinhsi.com: could not connect to host
-lotos-ag.ch: could not connect to host
+lotos-ag.ch: did not receive HSTS header
 lotsencafe.de: did not receive HSTS header
 lotuscloud.org: could not connect to host
 louduniverse.net: did not receive HSTS header
@@ -7473,6 +7435,7 @@ lumi.do: did not receive HSTS header
 lunarift.com: could not connect to host
 lunarrift.net: could not connect to host
 luneta.nearbuysystems.com: could not connect to host
+lunix.io: did not receive HSTS header
 luno.io: could not connect to host
 luody.info: could not connect to host
 luoe.ml: could not connect to host
@@ -7634,6 +7597,7 @@ markusabraham.com: did not receive HSTS header
 markusweimar.de: did not receive HSTS header
 marlen.cz: did not receive HSTS header
 marleyresort.com: did not receive HSTS header
+maroc-bivouac.com: did not receive HSTS header
 marriottvetcareers.com: could not connect to host
 marshut.net: could not connect to host
 martensson.io: did not receive HSTS header
@@ -7648,6 +7612,7 @@ martinp.no: could not connect to host
 martinreed.net: did not receive HSTS header
 martinrogalla.com: did not receive HSTS header
 marumagic.com: did not receive HSTS header
+marvinkeller.de: did not receive HSTS header
 marykshoup.com: did not receive HSTS header
 masa-yoga.com: did not receive HSTS header
 masa.li: could not connect to host
@@ -7697,7 +7662,6 @@ maurus-automation.de: did not receive HSTS header
 mausi.co: did not receive HSTS header
 mavisang.cf: could not connect to host
 mawe.red: could not connect to host
-max.gov: did not receive HSTS header
 maxima.at: did not receive HSTS header
 maximov.space: could not connect to host
 maxmachine.ind.br: could not connect to host
@@ -7733,6 +7697,7 @@ mediafinancelab.org: did not receive HSTS header
 mediamag.am: max-age too low: 0
 mediawikicn.org: could not connect to host
 medienservice-fritz.de: did not receive HSTS header
+medifab.online: did not receive HSTS header
 medirich.co: could not connect to host
 meditek-dv.ru: could not connect to host
 mediterenopmaandag.nl: did not receive HSTS header
@@ -7848,7 +7813,6 @@ mijnkredietpaspoort.nl: could not connect to host
 mikadesign.se: did not receive HSTS header
 mikaelemilsson.net: did not receive HSTS header
 mikeburns.com: could not connect to host
-mikedugan.org: did not receive HSTS header
 mikeg.de: did not receive HSTS header
 mikek.work: did not receive HSTS header
 mikeology.org: could not connect to host
@@ -7977,6 +7941,7 @@ moitur.com: could not connect to host
 mojizuri.jp: max-age too low: 86400
 mols.me: did not receive HSTS header
 molun.net: did not receive HSTS header
+momfulfilled.com: did not receive HSTS header
 mommel.com: could not connect to host
 mommelonline.de: could not connect to host
 momoka.moe: could not connect to host
@@ -8030,6 +7995,7 @@ motionfreight.com: could not connect to host
 motionpicturesolutions.com: did not receive HSTS header
 motorcheck.ie: did not receive HSTS header
 motoroilinfo.com: did not receive HSTS header
+motorsportdiesel.com: did not receive HSTS header
 motransportinfo.com: did not receive HSTS header
 mottvd.com: could not connect to host
 moudicat.com: max-age too low: 6307200
@@ -8046,9 +8012,8 @@ mozoa.net: could not connect to host
 mp3donusturucu.com: did not receive HSTS header
 mp3donusturucu.net: did not receive HSTS header
 mp3juices.is: could not connect to host
-mpintaamalabanna.it: did not receive HSTS header
 mpkossen.com: did not receive HSTS header
-mqas.net: could not connect to host
+mqas.net: did not receive HSTS header
 mr-hosting.com: could not connect to host
 mrawe.com: could not connect to host
 mrdani.net: could not connect to host
@@ -8060,7 +8025,7 @@ mrning.com: did not receive HSTS header
 mrnonz.com: max-age too low: 0
 mrparker.pw: could not connect to host
 mrpopat.in: did not receive HSTS header
-mrs-shop.com: could not connect to host
+mrs-shop.com: did not receive HSTS header
 mrsbairds.com: max-age too low: 86400
 msc-seereisen.net: max-age too low: 0
 mstd.tokyo: did not receive HSTS header
@@ -8213,6 +8178,7 @@ naudles.me: could not connect to host
 nav.jobs: could not connect to host
 naval.tf: could not connect to host
 navjobs.com: did not receive HSTS header
+nay.moe: did not receive HSTS header
 nbb.io: could not connect to host
 nbg-ha.de: could not connect to host
 ncc60205.info: could not connect to host
@@ -8237,7 +8203,7 @@ nemovement.org: could not connect to host
 neoani.me: did not receive HSTS header
 neofelhz.space: could not connect to host
 neonisi.com: could not connect to host
-neonnuke.tech: did not receive HSTS header
+neonnuke.tech: could not connect to host
 neosolution.ca: did not receive HSTS header
 nephy.jp: could not connect to host
 nepustil.net: could not connect to host
@@ -8491,7 +8457,7 @@ offshoremarineparts.com: did not receive HSTS header
 oficinadocelular.com.br: could not connect to host
 ofo2.com: did not receive HSTS header
 oganek.ie: could not connect to host
-oganime.com: did not receive HSTS header
+oganime.com: could not connect to host
 ogogoshop.com: could not connect to host
 ohm2013.org: did not receive HSTS header
 ohsocool.org: did not receive HSTS header
@@ -8546,7 +8512,6 @@ onlinecompliance.org: did not receive HSTS header
 onlinedemo.hu: could not connect to host
 onlinedeposit.us: could not connect to host
 onlinekasino.de: did not receive HSTS header
-onlinepokerspelen.be: did not receive HSTS header
 onlinepollsph.com: could not connect to host
 onlineschadestaat.nl: did not receive HSTS header
 onlinespielothek.com: did not receive HSTS header
@@ -8656,7 +8621,7 @@ ovuscloud.de: could not connect to host
 ovvy.net: did not receive HSTS header
 owncloud.help: could not connect to host
 ownmovies.fr: could not connect to host
-oxro.co: did not receive HSTS header
+oxro.co: could not connect to host
 oxygaming.com: did not receive HSTS header
 oxygenabsorbers.com: did not receive HSTS header
 oxymc.com: did not receive HSTS header
@@ -8698,7 +8663,7 @@ panni.me: could not connect to host
 panoranordic.net: could not connect to host
 pansu.space: could not connect to host
 pants-off.xyz: could not connect to host
-pantsu.cat: could not connect to host
+pantsu.cat: did not receive HSTS header
 papalytics.com: could not connect to host
 papeda.net: could not connect to host
 papelariadante.com.br: could not connect to host
@@ -8711,6 +8676,7 @@ parabhairavayoga.com: max-age too low: 0
 paragon.edu: did not receive HSTS header
 parent5446.us: could not connect to host
 parentmail.co.uk: did not receive HSTS header
+parfum-baza.ru: did not receive HSTS header
 paris-cyber.fr: did not receive HSTS header
 parisvox.info: did not receive HSTS header
 parithy.net: could not connect to host
@@ -8732,6 +8698,7 @@ partyvan.moe: could not connect to host
 partyvan.nl: could not connect to host
 partyvan.se: could not connect to host
 pascalchristen.ch: did not receive HSTS header
+pascaline-jouis.fr: did not receive HSTS header
 passumpsicbank.com: did not receive HSTS header
 passwd.io: could not connect to host
 passwordbox.com: did not receive HSTS header
@@ -8762,7 +8729,6 @@ pay.gigahost.dk: did not receive HSTS header
 payclixpayments.com: did not receive HSTS header
 payfreez.com: could not connect to host
 payload.tech: could not connect to host
-paymentaccuracy.gov: did not receive HSTS header
 payments-reference.org: could not connect to host
 payroll.ch: could not connect to host
 paytwopay.com: could not connect to host
@@ -8915,6 +8881,7 @@ pixelcode.com.au: could not connect to host
 pixelhero.co.uk: did not receive HSTS header
 pixi.chat: could not connect to host
 pixi.me: did not receive HSTS header
+pixiv.cat: did not receive HSTS header
 pizzadoc.ch: could not connect to host
 pjbet.mg: did not receive HSTS header
 pkautodesign.com: did not receive HSTS header
@@ -9121,6 +9088,7 @@ psicologoforensebarcelona.com: did not receive HSTS header
 pstudio.me: did not receive HSTS header
 psw.academy: could not connect to host
 psw.consulting: could not connect to host
+psylab.cc: did not receive HSTS header
 ptn.moscow: could not connect to host
 ptonet.com: could not connect to host
 ptrujillo.com: did not receive HSTS header
@@ -9516,7 +9484,6 @@ rugstorene.co.uk: did not receive HSTS header
 ruig.jp: could not connect to host
 ruitershoponline.nl: did not receive HSTS header
 rumoterra.com.br: could not connect to host
-rumplesinflatables.co.uk: did not receive HSTS header
 runawebinar.nl: could not connect to host
 runhardt.eu: did not receive HSTS header
 runtl.com: did not receive HSTS header
@@ -9574,7 +9541,7 @@ sampoznay.ru: did not receive HSTS header
 samraskauskas.com: could not connect to host
 samsen.club: could not connect to host
 sanasalud.org: could not connect to host
-sanatfilan.com: did not receive HSTS header
+sanatfilan.com: could not connect to host
 sandviks.com: did not receive HSTS header
 sanguoxiu.com: could not connect to host
 sanhei.ch: did not receive HSTS header
@@ -9626,7 +9593,7 @@ savvysuit.com: did not receive HSTS header
 sawamura-rental.com: did not receive HSTS header
 say-hanabi.com: could not connect to host
 sayhanabi.com: could not connect to host
-sazima.ru: did not receive HSTS header
+sazima.ru: could not connect to host
 sbobetfun.com: could not connect to host
 sbox-archives.com: could not connect to host
 sby.de: did not receive HSTS header
@@ -9643,6 +9610,7 @@ schnell-abnehmen.tips: did not receive HSTS header
 schnell-gold.com: could not connect to host
 scholl.io: could not connect to host
 schooltrends.co.uk: did not receive HSTS header
+schraugerrun.com: did not receive HSTS header
 schreiber-netzwerk.eu: did not receive HSTS header
 schreibnacht.de: did not receive HSTS header
 schrikdraad.net: did not receive HSTS header
@@ -9757,7 +9725,6 @@ semaf.at: max-age too low: 86400
 semantheme.fr: did not receive HSTS header
 semen3325.xyz: could not connect to host
 semenkovich.com: did not receive HSTS header
-semjonov.de: did not receive HSTS header
 semps-servers.de: could not connect to host
 sendash.com: could not connect to host
 sendmeback.de: did not receive HSTS header
@@ -9837,7 +9804,7 @@ shawnbsmith.me: did not receive HSTS header
 shawnh.net: could not connect to host
 shellsec.pw: did not receive HSTS header
 shep.co.il: did not receive HSTS header
-sheratan.web.id: could not connect to host
+sheratan.web.id: did not receive HSTS header
 shereallyheals.com: did not receive HSTS header
 shervik.ga: could not connect to host
 shg-pornographieabhaengigkeit.de: did not receive HSTS header
@@ -9905,7 +9872,7 @@ simfri.com: could not connect to host
 simnovo.net: did not receive HSTS header
 simobilklub.si: could not connect to host
 simod.org: could not connect to host
-simon-pokorny.com: did not receive HSTS header
+simon-pokorny.com: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsISiteSecurityService.processHeader]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: /builds/slave/m-cen-l64-periodicupdate-00000/getHSTSPreloadList.js :: processStsHeader :: line 116"  data: no]
 simon.butcher.name: max-age too low: 2629743
 simongong.net: did not receive HSTS header
 simonsaxon.com: did not receive HSTS header
@@ -9997,7 +9964,6 @@ smallshopit.com: did not receive HSTS header
 smart-mirror.de: did not receive HSTS header
 smart-ov.nl: could not connect to host
 smartbuyelectric.com: could not connect to host
-smartcleaningcenter.nl: did not receive HSTS header
 smartcoin.com.br: could not connect to host
 smartfon4you.ru: max-age too low: 0
 smarthomedna.com: did not receive HSTS header
@@ -10121,6 +10087,7 @@ speculor.net: could not connect to host
 spedition-transport-umzug.de: did not receive HSTS header
 speed-mailer.com: could not connect to host
 speedcounter.net: did not receive HSTS header
+speeds.vip: did not receive HSTS header
 speedway.com.pl: did not receive HSTS header
 speedy.lt: max-age too low: 0
 speedyprep.com: did not receive HSTS header
@@ -10194,7 +10161,6 @@ stargatepartners.com: did not receive HSTS header
 starmusic.ga: could not connect to host
 startuponcloud.com: max-age too low: 2678400
 stash.ai: did not receive HSTS header
-stassi.ch: did not receive HSTS header
 state-sponsored-actors.net: could not connect to host
 statementinsertsforless.com: did not receive HSTS header
 stateofexception.io: could not connect to host
@@ -10230,7 +10196,8 @@ stillblackhat.id: could not connect to host
 stinkytrashhound.com: could not connect to host
 stirlingpoon.net: could not connect to host
 stirlingpoon.xyz: could not connect to host
-stitthappens.com: did not receive HSTS header
+stitthappens.com: could not connect to host
+stjohnsc.com: did not receive HSTS header
 stkbn.com: could not connect to host
 stkeverneparishcouncil.org.uk: did not receive HSTS header
 stl.news: did not receive HSTS header
@@ -10447,7 +10414,6 @@ tavoittaja.fi: did not receive HSTS header
 tavopica.lt: did not receive HSTS header
 taxaudit.com: did not receive HSTS header
 taxbench.com: could not connect to host
-taxi-24std.de: did not receive HSTS header
 taxsnaps.co.nz: did not receive HSTS header
 tazj.in: did not receive HSTS header
 tazz.in: could not connect to host
@@ -10697,6 +10663,7 @@ tickreport.com: did not receive HSTS header
 ticktock.today: did not receive HSTS header
 tictactux.de: could not connect to host
 tidmore.us: could not connect to host
+tie-online.org: did not receive HSTS header
 tiendschuurstraat.nl: could not connect to host
 tiensnet.com: could not connect to host
 tierrarp.com: could not connect to host
@@ -10706,7 +10673,7 @@ tikutiku.pl: could not connect to host
 tildebot.com: could not connect to host
 tilient.eu: [Exception... "Component returned failure code: 0x80004005 (NS_ERROR_FAILURE) [nsISiteSecurityService.processHeader]"  nsresult: "0x80004005 (NS_ERROR_FAILURE)"  location: "JS frame :: /builds/slave/m-cen-l64-periodicupdate-00000/getHSTSPreloadList.js :: processStsHeader :: line 116"  data: no]
 tilikum.io: did not receive HSTS header
-tilkah.com.au: did not receive HSTS header
+tilkah.com.au: could not connect to host
 tillcraft.com: could not connect to host
 timbeilby.com: could not connect to host
 timbuktutimber.com: did not receive HSTS header
@@ -10745,6 +10712,7 @@ tjeckien.guide: could not connect to host
 tkappertjedemetamorfose.nl: could not connect to host
 tkarstens.de: did not receive HSTS header
 tkonstantopoulos.tk: could not connect to host
+tlach.cz: did not receive HSTS header
 tlcdn.net: could not connect to host
 tlo.hosting: could not connect to host
 tlo.link: could not connect to host
@@ -10844,7 +10812,7 @@ tpms4u.at: did not receive HSTS header
 tppdebate.org: did not receive HSTS header
 tracetracker.com: did not receive HSTS header
 tracker-gps.ch: could not connect to host
-trackingstream.com: did not receive HSTS header
+trackingstream.com: could not connect to host
 trackmeet.io: did not receive HSTS header
 tracktivity.com.au: could not connect to host
 trade-smart.ru: could not connect to host
@@ -11004,6 +10972,7 @@ ugisgutless.com: could not connect to host
 ugo.ninja: could not connect to host
 ugosadventures.com: could not connect to host
 uhm.io: did not receive HSTS header
+uitslagensoftware.nl: did not receive HSTS header
 ukas.com: did not receive HSTS header
 ukdropshipment.co.uk: did not receive HSTS header
 ukdropshipment.com: did not receive HSTS header
@@ -11112,7 +11081,6 @@ usercare.com: did not receive HSTS header
 userify.com: max-age too low: 0
 uslab.io: could not connect to host
 usr.nz: did not receive HSTS header
-ustr.gov: did not receive HSTS header
 utilitronium-shockwave.com: could not connect to host
 utleieplassen.no: could not connect to host
 utopiagalaxy.space: could not connect to host
@@ -11131,7 +11099,7 @@ uyym.com: could not connect to host
 uzmandroid.com: could not connect to host
 uzmandroid.net: could not connect to host
 uzmandroid.top: could not connect to host
-v-desk.ga: could not connect to host
+v-desk.ga: did not receive HSTS header
 v0rtex.xyz: could not connect to host
 v0tti.com: could not connect to host
 v12.co.uk: did not receive HSTS header
@@ -11262,6 +11230,7 @@ vincentkooijman.at: did not receive HSTS header
 vincentkooijman.nl: could not connect to host
 vinciconps4.it: could not connect to host
 viniferawineclub.com: did not receive HSTS header
+vinogradovka.com: did not receive HSTS header
 vinsetchampagne.fr: did not receive HSTS header
 vintageheartcoffee.com: max-age too low: 0
 vio.no: did not receive HSTS header
@@ -11272,7 +11241,7 @@ viplentes.com.br: did not receive HSTS header
 vipmusic.ga: could not connect to host
 viral8.jp: could not connect to host
 virginiacrimeanalysisnetwork.org: did not receive HSTS header
-virtualstrongbox.ca: could not connect to host
+virtualstrongbox.ca: did not receive HSTS header
 visanhigia.com: could not connect to host
 viserproject.com: did not receive HSTS header
 vision-painting.com: did not receive HSTS header
@@ -11289,7 +11258,6 @@ vitsoft.by: did not receive HSTS header
 vitta.me: did not receive HSTS header
 viva-french.com: did not receive HSTS header
 vivasports.com.br: could not connect to host
-vivianmaier.cn: did not receive HSTS header
 vivocloud.com: could not connect to host
 vivremoinscher.fr: did not receive HSTS header
 vizeat.com: did not receive HSTS header
@@ -11301,9 +11269,7 @@ voicesuk.co.uk: did not receive HSTS header
 voidserv.net: could not connect to host
 volbyzive.cz: did not receive HSTS header
 volcrado.com: did not receive HSTS header
-voliere-info.nl: did not receive HSTS header
 volkden.com: could not connect to host
-volkerwesselswave.nl: did not receive HSTS header
 voltotc.com: did not receive HSTS header
 vonavy-cukor.sk: could not connect to host
 vonavycukor.sk: could not connect to host
@@ -11376,6 +11342,7 @@ wapt.fr: did not receive HSTS header
 warandpeace.xyz: could not connect to host
 wardsegers.be: did not receive HSTS header
 warehost.de: did not receive HSTS header
+warekit.io: did not receive HSTS header
 warhistoryonline.com: did not receive HSTS header
 warped.com: did not receive HSTS header
 warrencreative.com: did not receive HSTS header
@@ -11451,6 +11418,8 @@ weddingibiza.nl: could not connect to host
 wedotrains.club: did not receive HSTS header
 weekly.fyi: could not connect to host
 wegenaer.nl: could not connect to host
+weicn.org: did not receive HSTS header
+weightreviews.com: did not receive HSTS header
 weirdesigns.com: did not receive HSTS header
 weiyuz.com: max-age too low: 6585555
 welkers.org: could not connect to host
@@ -11505,6 +11474,7 @@ wholesomeharvestbread.com: max-age too low: 86400
 whoshotya.de: did not receive HSTS header
 whysuck.com: could not connect to host
 wibruje.pl: did not receive HSTS header
+wideinfo.org: did not receive HSTS header
 widenews.org: did not receive HSTS header
 wienholding.at: max-age too low: 0
 wieninternational.at: did not receive HSTS header
@@ -11577,6 +11547,8 @@ woodworkertip.com: did not receive HSTS header
 woording.com: could not connect to host
 wootton95.com: could not connect to host
 wooviet.com: could not connect to host
+worcesterdance.org: did not receive HSTS header
+wordbits.net: did not receive HSTS header
 work-and-jockel.de: did not receive HSTS header
 workfone.io: did not receive HSTS header
 workingclassmedia.com: did not receive HSTS header
@@ -11694,6 +11666,7 @@ ximage.me: did not receive HSTS header
 ximens.me: could not connect to host
 xinbiji.cn: could not connect to host
 xinghuokeji.xin: could not connect to host
+xingiahanvisa.net: did not receive HSTS header
 xisa.it: could not connect to host
 xivpn.com: could not connect to host
 xiyu.moe: did not receive HSTS header
@@ -11940,6 +11913,7 @@ zohar.link: could not connect to host
 zollihood.ch: did not receive HSTS header
 zolotoy-standart.com.ua: did not receive HSTS header
 zomiac.pp.ua: could not connect to host
+zonadebolsa.es: did not receive HSTS header
 zoneminder.com: did not receive HSTS header
 zoners.si: did not receive HSTS header
 zonky.io: could not connect to host
diff --git a/security/manager/ssl/nsSTSPreloadList.inc b/security/manager/ssl/nsSTSPreloadList.inc
index 87653350dfa7..2ef1f3b8c915 100644
--- a/security/manager/ssl/nsSTSPreloadList.inc
+++ b/security/manager/ssl/nsSTSPreloadList.inc
@@ -8,7 +8,7 @@
 /*****************************************************************************/
 
 #include <stdint.h>
-const PRTime gPreloadListExpirationTime = INT64_C(1531684123172000);
+const PRTime gPreloadListExpirationTime = INT64_C(1531770672720000);
 %%
 0-1.party, 1
 0.me.uk, 1
@@ -178,6 +178,8 @@ const PRTime gPreloadListExpirationTime = INT64_C(1531684123172000);
 1359826938.rsc.cdn77.org, 1
 135vv.com, 1
 13826145000.com, 1
+1391kj.com, 1
+1395kj.com, 1
 1396.net, 1
 13th-dover.uk, 1
 1453914078.rsc.cdn77.org, 1
@@ -228,6 +230,7 @@ const PRTime gPreloadListExpirationTime = INT64_C(1531684123172000);
 19hundert84.de, 1
 1a-diamantscheiben.de, 1
 1a-vermessung.at, 1
+1a-werkstattgeraete.de, 1
 1aim.com, 1
 1cover.co.nz, 1
 1cover.com.au, 1
@@ -881,7 +884,6 @@ accudraftpaintbooths.com, 1
 accuritconsulting.com, 1
 accuritpresence.com, 1
 accwing.com, 1
-aceadvisory.biz, 1
 aceanswering.com, 1
 acecerts.co.uk, 1
 acecolleges.edu.au, 1
@@ -1246,7 +1248,6 @@ agiley.se, 1
 agilob.net, 1
 aging.gov, 1
 agingstop.net, 1
-agonswim.com, 0
 agoodmind.com, 1
 agoravm.tk, 1
 agoravox.fr, 1
@@ -2098,6 +2099,7 @@ annuaire-photographe.fr, 0
 anohana.org, 1
 anojan.com, 1
 anon-next.de, 1
+anonboards.com, 1
 anoncom.net, 1
 anoneko.com, 1
 anongoth.pl, 1
@@ -2247,7 +2249,6 @@ apk.li, 1
 apk4fun.com, 1
 apkoyunlar.club, 1
 apkriver.com, 1
-apl2bits.net, 1
 aplikaceproandroid.cz, 1
 aplis-online.de, 0
 aplpackaging.co.uk, 1
@@ -2323,7 +2324,6 @@ apptoutou.com, 1
 appuals.com, 1
 appui-de-fenetre.fr, 1
 appveyor.com, 1
-appzoojoo.be, 1
 aprefix.com, 1
 apretatuercas.es, 1
 aprovpn.com, 1
@@ -2419,7 +2419,7 @@ arenns.com, 1
 arent.kz, 1
 arenzanaphotography.com, 1
 areqgaming.com, 1
-ares-trading.de, 0
+ares-trading.de, 1
 arethsu.se, 1
 arfad.ch, 1
 arg.zone, 1
@@ -2511,6 +2511,7 @@ arsk1.com, 1
 art-et-culture.ch, 1
 artansoft.com, 1
 artboja.com, 1
+artbytik.ru, 1
 artdeco-photo.com, 1
 artea.ga, 1
 arteaga.co.uk, 1
@@ -2890,7 +2891,6 @@ auto-anleitung.de, 1
 auto-motor-i-sport.pl, 1
 auto-plus.tn, 1
 autoauctionsohio.com, 1
-autoauctionsvirginia.com, 1
 autobedrijfschalkoort.nl, 1
 autoclean-plus.ch, 1
 autocmall.com, 1
@@ -4029,6 +4029,7 @@ biboumail.fr, 1
 bibuch.com, 1
 bicecontracting.com, 1
 bicha.net, 1
+bichines.es, 1
 bichonfrise.com.br, 1
 bichonmaltes.com.br, 1
 bicranial.io, 1
@@ -4304,6 +4305,7 @@ bituptick.com, 1
 bitvegas.com, 1
 bitvest.io, 1
 bitwolk.nl, 1
+bitwrought.net, 1
 bitxel.com.co, 1
 bityes.org, 1
 biurokarier.edu.pl, 1
@@ -5223,7 +5225,6 @@ bubhub.io, 1
 buch-angucken.de, 1
 buchverlag-scholz.de, 1
 buck.com, 1
-buckmulligans.com, 1
 buckypaper.com, 1
 budaev-shop.ru, 1
 buddhismus.net, 1
@@ -5439,7 +5440,6 @@ byronwade.com, 1
 byrtz.de, 1
 bysb.net, 1
 byte-time.com, 1
-byte128.com, 1
 bytearts.net, 1
 bytebucket.org, 1
 bytecode.no, 1
@@ -5488,7 +5488,6 @@ c4539.com, 1
 c4k3.net, 1
 c7dn.com, 1
 ca-key.de, 1
-ca-terminal-multiservices.fr, 1
 ca.gparent.org, 1
 ca.search.yahoo.com, 0
 ca5.de, 1
@@ -5932,6 +5931,7 @@ cave-reynard.ch, 1
 cavevinsdefrance.fr, 1
 cavzodiaco.com.br, 1
 caylercapital.com, 1
+cayounglab.co.jp, 1
 cazaviajes.es, 1
 cazes.info, 1
 cb-crochet.com, 1
@@ -6106,6 +6106,7 @@ cfan.space, 1
 cfh.com, 1
 cfneia.org, 1
 cfno.org, 1
+cfo.gov, 1
 cfpa-formation.fr, 1
 cfsh.tk, 1
 cftcarouge.com, 1
@@ -6617,7 +6618,7 @@ cirugiasplasticas.com.mx, 1
 cirujanooral.com, 1
 cirurgicagervasio.com.br, 1
 cirurgicalucena.com.br, 1
-ciscodude.net, 1
+ciscodude.net, 0
 cisoaid.com, 1
 ciss.ltd, 1
 cisy.me, 1
@@ -6846,7 +6847,6 @@ clownish.co.il, 1
 cloxy.com, 1
 clr3.com, 1
 clsimage.com, 1
-clsimplex.com, 1
 clsoft.ch, 1
 clu-in.org, 1
 club-duomo.com, 1
@@ -7320,9 +7320,11 @@ constructive.men, 1
 consul.io, 1
 consultcelerity.com, 1
 consultingroupitaly.com, 1
+consultorcr.net, 1
 consultpetkov.com, 1
 consumer.gov, 1
 consumeractionlawgroup.com, 1
+consumerfiles.com, 1
 consumersentinel.gov, 1
 consumidor.gov, 1
 consuwijzer.nl, 1
@@ -7402,7 +7404,6 @@ copycrafter.net, 1
 copypoison.com, 1
 copyright-watch.org, 1
 copytrack.com, 1
-corbax.com, 1
 corbi.net.au, 1
 corbinhesse.com, 1
 cordeydesign.ch, 1
@@ -7466,7 +7467,6 @@ cosirex.com, 1
 coslinker.com, 1
 cosmechic.fr, 1
 cosmeticappraisal.com, 1
-cosmeticasimple.com, 1
 cosmeticos-naturales.com, 1
 cosmeticosdelivery.com.br, 1
 cosmeticosnet.com.br, 1
@@ -7580,6 +7580,7 @@ craigsimpson.scot, 1
 craigwfox.com, 1
 cralarm.de, 1
 crandall.io, 1
+cranems.com.ua, 1
 cranesafe.com, 1
 cranforddental.com, 1
 crapouill.es, 1
@@ -7774,7 +7775,6 @@ cryptoparty.at, 1
 cryptoparty.dk, 1
 cryptopartynewcastle.org, 1
 cryptopartyutah.org, 1
-cryptophobia.nl, 0
 cryptorival.com, 1
 cryptoseb.pw, 1
 cryptoshot.pw, 1
@@ -7813,7 +7813,7 @@ csmainframe.com, 1
 csokolade.hu, 1
 csp.ch, 1
 cspeti.hu, 1
-cspvalidator.org, 0
+cspvalidator.org, 1
 csru.net, 1
 css.direct, 1
 css.net, 1
@@ -8410,7 +8410,7 @@ dawoud.org, 1
 dawson-floridavilla.co.uk, 1
 day-peak.com, 1
 daylightpirates.org, 1
-dayman.net, 0
+dayman.net, 1
 days.one, 1
 daysoftheyear.com, 1
 db-sanity.com, 1
@@ -8878,7 +8878,6 @@ devzero.io, 1
 dewaard.de, 1
 dewalch.net, 1
 dewapress.com, 1
-dewebwerf.nl, 1
 dewinter.com, 1
 dexalo.de, 1
 dezeregio.nl, 1
@@ -9440,7 +9439,7 @@ domytermpaper.com, 1
 domythesis.net, 1
 domyzitrka.cz, 1
 donabeneko.jp, 1
-donateaday.net, 0
+donateaday.net, 1
 donfelino.tk, 0
 dongkexue.com, 1
 dongxuwang.com, 1
@@ -9678,6 +9677,7 @@ drjenafernandez.com, 1
 drjoe.ca, 1
 drjuanitacollier.com, 1
 drkhsh.at, 1
+drkmtrx.xyz, 1
 drlangsdon.com, 1
 drmayakato.com, 1
 drmcdaniel.com, 1
@@ -9849,6 +9849,7 @@ dustygroove.com, 1
 dustyspokesbnb.ca, 1
 dutch.desi, 1
 dutch1.nl, 1
+dutchessuganda.com, 1
 dutchrank.nl, 1
 dutchwanderers.nl, 1
 dutchweballiance.nl, 1
@@ -9978,6 +9979,7 @@ eames-clayton.us, 1
 eapestudioweb.com, 1
 earl.org.uk, 1
 earlyyearshub.com, 1
+earmarks.gov, 1
 earn.com, 1
 earth-people.org, 1
 earthsystemprediction.gov, 1
@@ -11982,13 +11984,13 @@ filhin.es, 1
 filhodohomem.com, 1
 filhomes.ph, 1
 fili.org, 1
+filidorwiese.nl, 1
 filingsmadeeasy.com, 1
 filip-prochazka.com, 1
 filippo.io, 1
 filipsebesta.com, 1
 filleritemsindia.com, 1
 fillitupchallenge.eu, 1
-fillmysuitca.se, 1
 fillo.sk, 1
 film-tutorial.com, 1
 film.photography, 1
@@ -13037,7 +13039,6 @@ gamblersgaming.eu, 1
 game-files.net, 0
 game-gentle.com, 1
 game7.de, 1
-gamebits.net, 1
 gamebrott.com, 1
 gamecard-shop.nl, 1
 gamecdn.com, 1
@@ -13618,6 +13619,7 @@ glenshere.com, 1
 glidingshop.cz, 1
 glidingshop.de, 1
 glidingshop.eu, 1
+glittersjabloon.nl, 1
 glloq.org, 1
 glob-coin.com, 1
 global-adult-webcams.com, 1
@@ -13661,6 +13663,7 @@ glueckskindter.de, 1
 glutenfreelife.co.nz, 1
 glyph.ws, 1
 glyxins.com, 1
+gm-assicurazioni.it, 1
 gm.search.yahoo.com, 0
 gmail.com, 0
 gmantra.org, 1
@@ -13816,7 +13819,6 @@ gorognyelv.hu, 1
 gorschenin.com, 1
 gosccs.com, 1
 gosciencegirls.com, 1
-gosharewood.com, 1
 goshawkdb.io, 1
 goshin-group.co.jp, 1
 gospelfollower.com, 1
@@ -13913,6 +13915,7 @@ grandcastles.co.uk, 1
 grandchamproofing.com, 1
 grandchene.ch, 1
 grande.coffee, 1
+grandefratellonews.com, 1
 grandeto.com, 1
 grandjunctionbrewing.com, 1
 grandmasfridge.org, 1
@@ -14298,6 +14301,7 @@ hachre.de, 1
 hack.club, 1
 hack.cz, 1
 hackademix.net, 1
+hackanders.com, 1
 hackattack.com, 1
 hackbarth.guru, 1
 hackbeil.name, 1
@@ -15684,7 +15688,7 @@ icsadviseurs.nl, 1
 icsfinomornasco.gov.it, 1
 icsfinomornasco.it, 1
 ict-concept.nl, 0
-ict-crew.nl, 0
+ict-crew.nl, 1
 ict-radar.com, 1
 ict-radar.nl, 1
 ictcareer.ch, 1
@@ -16429,6 +16433,7 @@ invisibles.ch, 1
 invisionita.com, 1
 invisiverse.com, 1
 invitescene.com, 1
+invitethemhome.com, 1
 invkao.com, 1
 invoiced.com, 1
 invoicefinance.com, 1
@@ -16486,7 +16491,6 @@ iplog.info, 1
 ipmonitoring.hu, 1
 ipmotion.ca, 1
 ipnetworking.net, 1
-ipo-times.com, 1
 ipokabu.net, 1
 ipomue.com, 0
 ipop.gr, 1
@@ -16512,7 +16516,6 @@ ir1s.com, 1
 iranianholiday.com, 1
 irayo.net, 1
 irc-results.com, 1
-ircmett.de, 1
 iready.ro, 1
 ireef.tv, 1
 irenekauer.com, 1
@@ -16691,6 +16694,7 @@ itchimes.com, 1
 itchy.nl, 1
 itchybrainscentral.com, 1
 itcko.sk, 1
+itdashboard.gov, 1
 itds-consulting.com, 1
 itds-consulting.cz, 1
 itds-consulting.eu, 1
@@ -16706,7 +16710,6 @@ itfh.eu, 1
 itfix.cz, 1
 itforge.nl, 1
 ithenrik.com, 1
-itilo.de, 1
 itiomassagem.com.br, 1
 itis.gov, 1
 itis4u.ch, 1
@@ -16916,7 +16919,7 @@ jamesheald.com, 1
 jameshemmings.co.uk, 1
 jameshost.net, 1
 jameshunt.us, 0
-jamesj.me, 1
+jamesj.me, 0
 jamesknd.uk, 0
 jamesmarsh.net, 1
 jamesmcdonald.com, 0
@@ -17158,6 +17161,7 @@ jet-stream.fr, 1
 jetapi.org, 1
 jetbbs.com, 1
 jetbrains.pw, 1
+jetflex.de, 1
 jetkittens.co.uk, 1
 jetmirshatri.com, 1
 jetsetboyz.net, 1
@@ -17224,7 +17228,6 @@ jino-jossy.appspot.com, 1
 jinshuju.net, 1
 jintaiyang123.org, 1
 jiogo.com, 1
-jiosongs.com, 1
 jirav.com, 1
 jiripudil.cz, 1
 jiveiaktivno.bg, 1
@@ -17565,7 +17568,6 @@ jugendsuenden.info, 1
 jugh.de, 1
 juhakoho.com, 1
 juice.codes, 1
-juiced.gs, 1
 juku-info.top, 1
 juku-wing.jp, 1
 jule-spil.dk, 1
@@ -18076,7 +18078,6 @@ ketosecology.co.uk, 1
 kettner.com, 1
 ketty-voyance.com, 1
 kevinapease.com, 1
-kevinbowers.me, 1
 kevincox.ca, 0
 kevindekoninck.com, 0
 kevinfoley.cc, 1
@@ -18305,6 +18306,7 @@ kiwipayments.com, 1
 kiwiplace.com, 1
 kj-prince.com, 1
 kj1396.net, 1
+kj1397.com, 1
 kjaer.io, 1
 kjarni.cc, 1
 kjarrval.is, 1
@@ -18839,7 +18841,6 @@ la-cave-a-nodo.fr, 1
 la-compagnie-des-elfes.fr, 1
 la-ganiere.com, 1
 la-maison.ch, 1
-la-maison.eu, 1
 la-petite-entreprise.com, 1
 la-tourmaline.ch, 1
 laassari.me, 1
@@ -18907,7 +18908,6 @@ lagerauftrag.info, 1
 lagit.in, 1
 laglab.org, 0
 laguiadelvaron.com, 1
-laguinguette.fr, 1
 lahora.com.ec, 1
 lain.at, 1
 laindonleisure.co.uk, 1
@@ -19357,7 +19357,6 @@ leowkahman.com, 1
 lep.gov, 1
 lepenetapeti.com, 1
 lepiquillo.fr, 1
-leponton-lorient.fr, 1
 leprado.com, 1
 lepsos.com, 1
 lereporter.ma, 1
@@ -19713,7 +19712,6 @@ lionlyrics.com, 1
 lionsdeal.com, 1
 lipartydepot.com, 1
 lipex.com, 1
-lipo.lol, 1
 lipoabaltimore.org, 1
 liqd.net, 1
 liquid.cz, 1
@@ -20251,7 +20249,6 @@ lunidea.ch, 1
 lunidea.com, 1
 lunight.ml, 1
 lunis.net, 1
-lunix.io, 1
 lunorian.is, 1
 luoe.me, 1
 luoh.cc, 1
@@ -20813,7 +20810,6 @@ marlonschultz.de, 1
 marlosoft.net, 1
 marmolesromero.com, 1
 marmotte.love, 1
-maroc-bivouac.com, 1
 marocemploi.co, 1
 marocmail.ma, 1
 marotero.com, 1
@@ -20856,7 +20852,6 @@ maru-life.com, 1
 maruhoi.com, 1
 marustat.ru, 1
 marvelmoviemarathon.com, 1
-marvinkeller.de, 1
 marxist.party, 1
 marxmyths.org, 1
 maryeclark.com, 1
@@ -20978,7 +20973,7 @@ matthiasott.com, 1
 matthiasschwab.de, 1
 matthiasweiler.de, 0
 matthieuschlosser.fr, 1
-matthijssen.info, 0
+matthijssen.info, 1
 mattia98.org, 1
 mattiascibien.net, 1
 mattisam.com, 1
@@ -21005,6 +21000,7 @@ mawidabp.com, 1
 mawidaca.com, 1
 max-moeglich.de, 1
 max-went.pl, 1
+max.gov, 1
 maxbruckner.de, 1
 maxbruckner.org, 1
 maxbytes.nl, 0
@@ -21218,7 +21214,6 @@ medicinia.com.br, 1
 medicinskavranje.edu.rs, 1
 medicocompetente.it, 1
 medicoresponde.com.br, 1
-medifab.online, 1
 medifi.com, 1
 medigap-quote.net, 1
 medinside.ch, 1
@@ -21640,6 +21635,7 @@ mike2k.de, 1
 mikebelanger.ca, 1
 mikeblog.site, 1
 mikecb.org, 1
+mikedugan.org, 1
 mikegarnett.co.uk, 1
 mikegerwitz.com, 1
 mikehamburg.com, 1
@@ -22054,7 +22050,6 @@ molti.hu, 1
 molunerfinn.com, 1
 molwick.com, 1
 momentumdash.com, 1
-momfulfilled.com, 1
 momirfarooq.com, 1
 momozeit.de, 1
 momstableonline.com, 1
@@ -22233,7 +22228,6 @@ motorbiketourhanoi.com, 1
 motorpointarenacardiff.co.uk, 1
 motorring.ru, 1
 motorsplus.com, 0
-motorsportdiesel.com, 1
 motoryachtclub-radolfzell.de, 1
 motosikletevi.com, 1
 motostorie.blog, 0
@@ -22292,6 +22286,7 @@ mpetroff.net, 1
 mpg-universal.com, 1
 mpg.ovh, 1
 mpi-sa.fr, 1
+mpintaamalabanna.it, 1
 mplanetphl.fr, 1
 mplant.io, 1
 mplicka.cz, 1
@@ -23013,7 +23008,6 @@ navstevnik.sk, 1
 navycs.com, 1
 nawir.de, 1
 nawroth.info, 1
-nay.moe, 1
 nayahe.ru, 1
 nayanaas.com, 1
 nazevfirmy.cz, 1
@@ -24348,6 +24342,7 @@ onlinelegalmarketing.com, 1
 onlinelegalmedia.com, 1
 onlinelighting.com.au, 1
 onlinemarketingtraining.co.uk, 1
+onlinepokerspelen.be, 1
 onlinerollout.de, 1
 onlinestoreninjas.com, 1
 onlineth.com, 0
@@ -24935,7 +24930,6 @@ pardnoy.com, 1
 parentheseardenne.be, 1
 parentinterview.com, 1
 parentsintouch.co.uk, 1
-parfum-baza.ru, 1
 pariga.co.uk, 1
 paris-store.com, 1
 parisderriere.fr, 1
@@ -25003,7 +24997,6 @@ pascal-bourhis.com, 1
 pascal-bourhis.net, 1
 pascal-kannchen.de, 1
 pascal-wittmann.de, 1
-pascaline-jouis.fr, 1
 pascalleguern.com, 1
 pascalmathis.com, 1
 pascalmathis.me, 1
@@ -25148,6 +25141,7 @@ paylike.io, 1
 payloc.io, 1
 payme.uz, 1
 payment-network.com, 1
+paymentaccuracy.gov, 1
 payments.google.com, 1
 paymerang.com, 1
 paymill.com, 1
@@ -25730,7 +25724,6 @@ pixelrain.info, 1
 pixelsquared.us, 1
 pixelurbia.com, 1
 pixelution.at, 1
-pixiv.cat, 1
 pixiv.moe, 1
 pixivimg.me, 1
 pixlfox.com, 0
@@ -26675,7 +26668,6 @@ psychoco.net, 1
 psychotherapie-kp.de, 1
 psydix.org, 1
 psyk.yt, 1
-psylab.cc, 1
 psylab.re, 1
 psylab.vip, 1
 psynapse.net.au, 1
@@ -28268,6 +28260,7 @@ rulu.tv, 1
 rulutv.com, 1
 rumlager.de, 1
 rummel-platz.de, 1
+rumplesinflatables.co.uk, 1
 rumtaste.com, 1
 rumtaste.de, 1
 run-forrest.run, 1
@@ -28333,7 +28326,7 @@ ryanbritton.com, 1
 ryancarter.co.uk, 1
 ryanhowell.io, 0
 ryankearney.com, 0
-ryanmcdonough.co.uk, 1
+ryanmcdonough.co.uk, 0
 ryansmithphotography.com, 1
 ryazan-region.ru, 1
 rybox.info, 1
@@ -28785,7 +28778,7 @@ schlabbi.com, 0
 schlachter.ca, 1
 schlafguru.com, 1
 schlagenhauf.info, 1
-schlagma.de, 1
+schlagma.de, 0
 schlarp.com, 1
 schlechtewitze.com, 1
 schlossereieder.at, 1
@@ -28831,7 +28824,6 @@ schrauger.info, 1
 schrauger.net, 1
 schrauger.org, 1
 schrauger.run, 1
-schraugerrun.com, 1
 schreibers.ca, 1
 schreinerei-jahreis.de, 1
 schreinerei-wortmann.de, 1
@@ -29217,6 +29209,7 @@ sementes.gratis, 1
 semianalog.com, 1
 seminariruum.ee, 1
 semiocast.com, 1
+semjonov.de, 1
 semmlers.com, 1
 semox.de, 1
 semps-2fa.de, 1
@@ -29749,7 +29742,7 @@ silentkernel.fr, 0
 silentmode.com, 1
 silentundo.org, 1
 silerfamily.net, 1
-siliconchip.me, 0
+siliconchip.me, 1
 silkebaekken.no, 1
 sillisalaatti.fi, 1
 sillysnapz.co.uk, 1
@@ -30214,6 +30207,7 @@ smartandcom.ch, 1
 smartandhappychild.ro, 1
 smartbiz.vn, 1
 smartcheck.gov, 1
+smartcleaningcenter.nl, 1
 smartcpa.ca, 1
 smarterskies.gov, 1
 smartest-trading.com, 1
@@ -30679,7 +30673,6 @@ speechndraw.com, 1
 speeddate.it, 0
 speedof.me, 1
 speedracer.ca, 1
-speeds.vip, 1
 speedsportofhull.co.uk, 1
 speedtailors.com, 1
 speedtest-russia.com, 1
@@ -31012,6 +31005,7 @@ startuppeople.co.uk, 1
 startupum.ru, 1
 starwatches.eu, 1
 starwins.co.uk, 1
+stassi.ch, 1
 stastka.ch, 1
 stat.ink, 1
 state-of-body-and-mind.com, 1
@@ -31200,7 +31194,6 @@ stitchfiddle.com, 1
 stivesbouncycastlehire.co.uk, 1
 stjohnin.com, 1
 stjohnmiami.org, 1
-stjohnsc.com, 1
 stlu.de, 1
 stlucasmuseum.org, 1
 stlukesbrandon.org, 1
@@ -31965,6 +31958,7 @@ taunhanh.us, 1
 tavolaquadrada.com.br, 1
 tavsys.net, 1
 taxaroo.com, 1
+taxi-24std.de, 1
 taxi-chamonix.fr, 1
 taxi-collectif.ch, 1
 taxi-puck.pl, 1
@@ -32127,7 +32121,7 @@ techshift.eu, 1
 techshift.nl, 1
 techshift.se, 1
 techtalks.no, 1
-techtuts.info, 0
+techtuts.info, 1
 techunit.org, 1
 techvalue.gr, 1
 techviewforum.com, 1
@@ -32845,7 +32839,6 @@ ticketsvergleichen.de, 1
 tickit.ca, 1
 tid.jp, 1
 tidycustoms.net, 1
-tie-online.org, 1
 tielectric.ch, 1
 tiendafetichista.com, 1
 tiendavertigo.com, 1
@@ -33000,7 +32993,6 @@ tkn.tokyo, 1
 tkts.cl, 1
 tkusano.jp, 1
 tkw01536.de, 1
-tlach.cz, 1
 tlca.org, 1
 tlcnet.info, 1
 tlehseasyads.com, 1
@@ -33939,7 +33931,7 @@ u2fsecuritykeys.com, 1
 u4mh-dev-accesscontroller.azurewebsites.net, 1
 u4mh-dev-portal.azurewebsites.net, 1
 u5b.de, 0
-u5r.nl, 0
+u5r.nl, 1
 ua.search.yahoo.com, 0
 uae-company-service.com, 1
 uahs.org.uk, 1
@@ -34007,7 +33999,6 @@ uiberlay.cz, 1
 uicchy.com, 1
 uiop.link, 1
 uitgeverij-deviant.nl, 1
-uitslagensoftware.nl, 1
 ujob.com.cn, 1
 uk.dating, 1
 uk.search.yahoo.com, 0
@@ -34324,6 +34315,7 @@ uspsoig.gov, 1
 ussm.gov, 1
 ussuka.com, 1
 ust.space, 1
+ustr.gov, 0
 usualbeings.com, 1
 uswitch.com, 1
 ut-addicted.com, 1
@@ -34809,7 +34801,6 @@ vinicius.sl, 1
 vinilosdecorativos.net, 1
 vinner.com.au, 1
 vinnie.gq, 1
-vinogradovka.com, 1
 vinolli.de, 1
 vinovum.net, 1
 vintagebandfestival.org, 1
@@ -34909,6 +34900,7 @@ vivamusic.es, 1
 vivanosports.com.br, 1
 vivatv.com.tw, 1
 vivendi.de, 1
+vivianmaier.cn, 1
 vivid-academy.com, 1
 vividinflatables.co.uk, 1
 vividlumen.com, 1
@@ -34990,9 +34982,11 @@ volcain.io, 1
 volcanconcretos.com, 1
 volga.us, 1
 volgavibes.ru, 0
+voliere-info.nl, 0
 volker-gropp.de, 1
 volkergropp.de, 1
 volkerwesselstransfer.nl, 1
+volkerwesselswave.nl, 1
 volkswurst.de, 1
 vollans.id.au, 1
 voloevents.com, 1
@@ -35020,7 +35014,7 @@ vorodevops.com, 1
 vos-fleurs.ch, 1
 vos-fleurs.com, 1
 vosgym.jp, 1
-voshod.org, 0
+voshod.org, 1
 vosjesweb.nl, 1
 vosky.fr, 1
 vosn.de, 1
@@ -35224,7 +35218,6 @@ waonui.io, 1
 warcraftjournal.org, 1
 wardow.com, 1
 warebouncycastles.co.uk, 1
-warekit.io, 1
 warekon.com, 1
 warekon.dk, 1
 warenits.at, 1
@@ -35513,12 +35506,10 @@ wegotcookies.com, 1
 wegvielfalt.de, 1
 wehostdnn.com, 1
 weibomiaopai.com, 1
-weicn.org, 1
 weideheuvel.org, 1
 weidmannfibertechnology.com, 1
 weien.org, 1
 weigelia.nl, 1
-weightreviews.com, 1
 weiji.ga, 1
 weiler.xyz, 0
 weils.net, 1
@@ -35777,7 +35768,6 @@ wickrath.net, 1
 widdleguy.com, 1
 wideboxmacau.com, 0
 widegab.com, 1
-wideinfo.org, 1
 widemann.de, 1
 widememory.com, 1
 widmer.bz, 1
@@ -36063,10 +36053,8 @@ wootware.co.za, 1
 worcade.net, 1
 worcesterbouncycastlehire.co.uk, 1
 worcesterbouncycastles.co.uk, 1
-worcesterdance.org, 1
 worcesterfestival.co.uk, 1
 word-grabber.com, 1
-wordbits.net, 1
 wordcounter.net, 1
 wordher.com, 1
 wordlessecho.com, 1
@@ -36462,7 +36450,6 @@ xin-in.com, 1
 xin-in.net, 1
 xing-in.net, 1
 xing.ml, 1
-xingiahanvisa.net, 1
 xiqi.us, 1
 xirion.net, 1
 xiyu.it, 0
@@ -37341,7 +37328,6 @@ zokster.net, 1
 zolokar.xyz, 1
 zombiesecured.com, 1
 zomerschoen.nl, 1
-zonadebolsa.es, 1
 zone-produkte.de, 0
 zone39.com, 1
 zonecb.com, 1

From 1373cc1dac4510c47fcba9f2c817c380a4bf0e29 Mon Sep 17 00:00:00 2001
From: ffxbld <none@none>
Date: Mon, 12 Mar 2018 12:54:30 -0700
Subject: [PATCH 47/50] No bug, Automated HPKP preload list update from host
 bld-linux64-spot-302 - a=hpkp-update

---
 security/manager/ssl/StaticHPKPins.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/manager/ssl/StaticHPKPins.h b/security/manager/ssl/StaticHPKPins.h
index 3497fa1e3a0b..9b78976b1a80 100644
--- a/security/manager/ssl/StaticHPKPins.h
+++ b/security/manager/ssl/StaticHPKPins.h
@@ -1163,4 +1163,4 @@ static const TransportSecurityPreload kPublicKeyPinningPreloadList[] = {
 
 static const int32_t kUnknownId = -1;
 
-static const PRTime kPreloadPKPinsExpirationTime = INT64_C(1529264935824000);
+static const PRTime kPreloadPKPinsExpirationTime = INT64_C(1529351485588000);

From 120af4f0d40e6408666ee923b91ad3f25bd5c9f7 Mon Sep 17 00:00:00 2001
From: Margareta Eliza Balazs <ebalazs@mozilla.com>
Date: Tue, 13 Mar 2018 01:07:25 +0200
Subject: [PATCH 48/50] Backed out changeset af023ff0275b (bug 1438912) for
 merge conflicts

---
 devtools/client/memory/components/Census.js   |  1 -
 .../client/memory/components/DominatorTree.js |  1 -
 .../client/memory/components/Individuals.js   |  1 -
 .../components/jit-optimizations.js           |  1 -
 .../performance/components/waterfall-tree.js  |  1 -
 .../shared/components/VirtualizedTree.js      | 10 +----
 .../test/mochitest/test_tree_06.html          | 41 +++----------------
 7 files changed, 7 insertions(+), 49 deletions(-)

diff --git a/devtools/client/memory/components/Census.js b/devtools/client/memory/components/Census.js
index 11dc27bb7d29..1525c6f764a9 100644
--- a/devtools/client/memory/components/Census.js
+++ b/devtools/client/memory/components/Census.js
@@ -49,7 +49,6 @@ class Census extends Component {
 
     return Tree({
       autoExpandDepth: 0,
-      preventNavigationOnArrowRight: false,
       focused: census.focused,
       getParent: node => {
         const parent = parentMap[node.id];
diff --git a/devtools/client/memory/components/DominatorTree.js b/devtools/client/memory/components/DominatorTree.js
index d83f0cf03394..12c9dc8b37e7 100644
--- a/devtools/client/memory/components/DominatorTree.js
+++ b/devtools/client/memory/components/DominatorTree.js
@@ -134,7 +134,6 @@ class DominatorTree extends Component {
     return Tree({
       key: "dominator-tree-tree",
       autoExpandDepth: DOMINATOR_TREE_AUTO_EXPAND_DEPTH,
-      preventNavigationOnArrowRight: false,
       focused: dominatorTree.focused,
       getParent: node =>
         node instanceof DominatorTreeLazyChildren
diff --git a/devtools/client/memory/components/Individuals.js b/devtools/client/memory/components/Individuals.js
index e22affc3c705..c9ee79fd5fa9 100644
--- a/devtools/client/memory/components/Individuals.js
+++ b/devtools/client/memory/components/Individuals.js
@@ -35,7 +35,6 @@ class Individuals extends Component {
     return Tree({
       key: "individuals-tree",
       autoExpandDepth: 0,
-      preventNavigationOnArrowRight: false,
       focused: individuals.focused,
       getParent: node => null,
       getChildren: node => [],
diff --git a/devtools/client/performance/components/jit-optimizations.js b/devtools/client/performance/components/jit-optimizations.js
index d3a49710caa5..109123d9fede 100644
--- a/devtools/client/performance/components/jit-optimizations.js
+++ b/devtools/client/performance/components/jit-optimizations.js
@@ -189,7 +189,6 @@ class JITOptimizations extends Component {
 
     return Tree({
       autoExpandDepth,
-      preventNavigationOnArrowRight: false,
       getParent: node => {
         let site = getSite(node.id);
         let parent;
diff --git a/devtools/client/performance/components/waterfall-tree.js b/devtools/client/performance/components/waterfall-tree.js
index 6fd66006ba7f..c8eda9f69e57 100644
--- a/devtools/client/performance/components/waterfall-tree.js
+++ b/devtools/client/performance/components/waterfall-tree.js
@@ -163,7 +163,6 @@ class WaterfallTree extends Component {
 
   render() {
     return Tree({
-      preventNavigationOnArrowRight: false,
       getRoots: this._getRoots,
       getParent: this._getParent,
       getChildren: this._getChildren,
diff --git a/devtools/client/shared/components/VirtualizedTree.js b/devtools/client/shared/components/VirtualizedTree.js
index bded3e958297..d2eb0f66af2d 100644
--- a/devtools/client/shared/components/VirtualizedTree.js
+++ b/devtools/client/shared/components/VirtualizedTree.js
@@ -198,10 +198,6 @@ class Tree extends Component {
       // Handle when item is activated with a keyboard (using Space or Enter)
       onActivate: PropTypes.func,
 
-      // Indicates if pressing ArrowRight key should only expand expandable node
-      // or if the selection should also move to the next node.
-      preventNavigationOnArrowRight: PropTypes.bool,
-
       // The depth to which we should automatically expand new items.
       autoExpandDepth: PropTypes.number,
 
@@ -232,7 +228,6 @@ class Tree extends Component {
   static get defaultProps() {
     return {
       autoExpandDepth: AUTO_EXPAND_DEPTH,
-      preventNavigationOnArrowRight: true,
     };
   }
 
@@ -507,10 +502,9 @@ class Tree extends Component {
         break;
 
       case "ArrowRight":
-        if (this.props.getChildren(this.props.focused).length &&
-            !this.props.isExpanded(this.props.focused)) {
+        if (!this.props.isExpanded(this.props.focused)) {
           this._onExpand(this.props.focused);
-        } else if (!this.props.preventNavigationOnArrowRight) {
+        } else {
           this._focusNextNode();
         }
         break;
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_06.html b/devtools/client/shared/components/test/mochitest/test_tree_06.html
index f6790675d148..ad1b342f31e8 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_06.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_06.html
@@ -16,17 +16,12 @@ Test keyboard navigation with the Tree component.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-
-"use strict";
-
 window.onload = async function () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
-    const { Simulate } =
-      browserRequire("devtools/client/shared/vendor/react-dom-test-utils");
-    const Tree =
-      createFactory(browserRequire("devtools/client/shared/components/VirtualizedTree"));
+    const { Simulate } = browserRequire("devtools/client/shared/vendor/react-dom-test-utils");
+    const Tree = createFactory(browserRequire("devtools/client/shared/components/VirtualizedTree"));
 
     function renderTree(props) {
       const treeProps = Object.assign({},
@@ -180,8 +175,7 @@ window.onload = async function () {
       "M:false",
       "-N:false",
       "--O:true",
-    ], "After the DOWN, O should still be focused " +
-       "and we shouldn't have overflowed past it.");
+    ], "After the DOWN, O should still be focused and we shouldn't have overflowed past it.");
 
     // LEFT --------------------------------------------------------------------
 
@@ -252,30 +246,7 @@ window.onload = async function () {
       "--O:false",
     ], "After the RIGHT, E's children should be expanded again.");
 
-    info("Right on already expanded node.");
-    Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowRight" });
-    await forceRender(tree);
-
-    isRenderedTree(document.body.textContent, [
-      "A:false",
-      "-B:false",
-      "--E:true",
-      "---K:false",
-      "---L:false",
-      "--F:false",
-      "--G:false",
-      "-C:false",
-      "--H:false",
-      "--I:false",
-      "-D:false",
-      "--J:false",
-      "M:false",
-      "-N:false",
-      "--O:false",
-    ], "After the RIGHT on already expanded node, E should remain focused.");
-
-    info("Right when preventNavigationOnArrowRight is unset to go to next item.");
-    renderTree({ focused: "E", preventNavigationOnArrowRight: false });
+    info("Right to go to next item.");
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowRight" });
     await forceRender(tree);
 
@@ -304,8 +275,6 @@ window.onload = async function () {
       { key: "ArrowDown", metaKey: true },
       { key: "ArrowDown", shiftKey: true },
     ];
-    await forceRender(tree);
-
     for (let key of keysWithModifier) {
       Simulate.keyDown(document.querySelector(".tree"), key);
       await forceRender(tree);
@@ -328,7 +297,7 @@ window.onload = async function () {
         "--O:false",
       ], "After DOWN + (alt|ctrl|meta|shift), K should remain focused.");
     }
-  } catch (e) {
+  } catch(e) {
     ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
   } finally {
     SimpleTest.finish();

From 65347670dfcc929aa6c61012af5aaea9ee82e376 Mon Sep 17 00:00:00 2001
From: Margareta Eliza Balazs <ebalazs@mozilla.com>
Date: Tue, 13 Mar 2018 01:07:54 +0200
Subject: [PATCH 49/50] Backed out 3 changesets (bug 1440321) for merge
 conflicts

Backed out changeset 746fce6799db (bug 1440321)
Backed out changeset f3baa6a3bedc (bug 1440321)
Backed out changeset ee2c71862489 (bug 1440321)
---
 .../client/aboutdebugging/modules/worker.js   |  16 +--
 .../test/browser_addons_debug_bootstrapped.js |  18 +--
 .../test/browser_addons_debug_info.js         |  52 ++++----
 .../test/browser_addons_debug_webextension.js |  10 +-
 ...ser_addons_debug_webextension_inspector.js |  10 +-
 .../browser_addons_debug_webextension_nobg.js |  10 +-
 ...browser_addons_debug_webextension_popup.js |  14 +--
 .../browser_addons_debugging_initial_state.js |  18 +--
 .../test/browser_addons_install.js            |  40 +++---
 .../test/browser_addons_reload.js             |  56 ++++-----
 .../test/browser_addons_remove.js             |  40 +++---
 .../test/browser_addons_toggle_debug.js       |  14 +--
 .../test/browser_page_not_found.js            |  18 +--
 .../test/browser_service_workers.js           |  16 +--
 .../browser_service_workers_fetch_flag.js     |  22 ++--
 ...r_service_workers_multi_content_process.js |  26 ++--
 .../browser_service_workers_not_compatible.js |  24 ++--
 .../test/browser_service_workers_push.js      |  26 ++--
 .../browser_service_workers_push_service.js   |  24 ++--
 .../test/browser_service_workers_start.js     |  28 ++---
 .../test/browser_service_workers_status.js    |  22 ++--
 .../test/browser_service_workers_timeout.js   |  30 ++---
 .../browser_service_workers_unregister.js     |  20 +--
 .../aboutdebugging/test/browser_tabs.js       |  24 ++--
 devtools/client/aboutdebugging/test/head.js   |  64 +++++-----
 .../client/canvasdebugger/canvasdebugger.js   |   1 +
 .../client/canvasdebugger/snapshotslist.js    |  46 +++----
 .../test/browser_canvas-actor-test-01.js      |   6 +-
 .../test/browser_canvas-actor-test-02.js      |  16 +--
 .../test/browser_canvas-actor-test-03.js      |  14 +--
 .../test/browser_canvas-actor-test-04.js      |  14 +--
 .../test/browser_canvas-actor-test-05.js      |  14 +--
 .../test/browser_canvas-actor-test-06.js      |  22 ++--
 .../test/browser_canvas-actor-test-07.js      |  32 ++---
 .../test/browser_canvas-actor-test-08.js      |  14 +--
 .../test/browser_canvas-actor-test-09.js      |  14 +--
 .../test/browser_canvas-actor-test-10.js      |  46 +++----
 .../test/browser_canvas-actor-test-11.js      |  32 ++---
 .../test/browser_canvas-actor-test-12.js      |  14 +--
 .../browser_canvas-frontend-call-highlight.js |  10 +-
 .../test/browser_canvas-frontend-call-list.js |  10 +-
 .../browser_canvas-frontend-call-search.js    |  14 +--
 .../browser_canvas-frontend-call-stack-01.js  |  18 +--
 .../browser_canvas-frontend-call-stack-02.js  |  18 +--
 .../browser_canvas-frontend-call-stack-03.js  |  12 +-
 .../test/browser_canvas-frontend-clear.js     |  14 +--
 ...browser_canvas-frontend-img-screenshots.js |  10 +-
 ...owser_canvas-frontend-img-thumbnails-01.js |  10 +-
 ...owser_canvas-frontend-img-thumbnails-02.js |  16 +--
 .../test/browser_canvas-frontend-open.js      |   6 +-
 .../test/browser_canvas-frontend-record-01.js |  12 +-
 .../test/browser_canvas-frontend-record-02.js |  14 +--
 .../test/browser_canvas-frontend-record-03.js |  10 +-
 .../test/browser_canvas-frontend-record-04.js |  12 +-
 .../test/browser_canvas-frontend-reload-01.js |  10 +-
 .../test/browser_canvas-frontend-reload-02.js |  14 +--
 .../test/browser_canvas-frontend-slider-01.js |  10 +-
 .../test/browser_canvas-frontend-slider-02.js |  32 ++---
 ...wser_canvas-frontend-snapshot-select-01.js |  18 +--
 ...wser_canvas-frontend-snapshot-select-02.js |  10 +-
 .../test/browser_canvas-frontend-stepping.js  |  10 +-
 .../test/browser_canvas-frontend-stop-01.js   |  12 +-
 .../test/browser_canvas-frontend-stop-02.js   |  12 +-
 .../test/browser_canvas-frontend-stop-03.js   |  12 +-
 .../test/browser_profiling-canvas.js          |  14 +--
 .../test/browser_profiling-webgl.js           |  26 ++--
 devtools/client/canvasdebugger/test/head.js   |  34 +++--
 devtools/client/commandline/test/head.js      |   1 -
 .../debugger/new/test/mochitest/head.js       |   1 -
 .../client/debugger/test/mochitest/head.js    |   1 -
 devtools/client/dom/dom-panel.js              |  11 +-
 devtools/client/dom/test/browser_dom_array.js |   6 +-
 devtools/client/dom/test/browser_dom_basic.js |   6 +-
 .../client/dom/test/browser_dom_refresh.js    |   8 +-
 devtools/client/dom/test/head.js              |   6 +-
 devtools/client/framework/connect/connect.js  |  19 +--
 devtools/client/framework/devtools.js         |  29 ++---
 devtools/client/framework/sidebar.js          |  13 +-
 .../framework/test/browser_browser_toolbox.js |   2 +-
 .../test/browser_browser_toolbox_debugger.js  |  13 +-
 .../framework/test/browser_devtools_api.js    |  10 +-
 ...browser_ignore_toolbox_network_requests.js |  10 +-
 .../framework/test/browser_keybindings_02.js  |  14 +--
 .../framework/test/browser_keybindings_03.js  |  16 +--
 .../client/framework/test/browser_menu_api.js |  32 ++---
 .../framework/test/browser_source_map-01.js   |  16 +--
 .../test/browser_source_map-absolute.js       |  12 +-
 .../test/browser_source_map-cross-domain.js   |   6 +-
 .../framework/test/browser_source_map-init.js |   6 +-
 .../test/browser_source_map-inline.js         |  14 +--
 .../test/browser_source_map-no-race.js        |   6 +-
 .../test/browser_source_map-reload.js         |  18 +--
 .../framework/test/browser_target_from_url.js |  40 +++---
 .../framework/test/browser_target_support.js  |  18 +--
 .../test/browser_toolbox_getpanelwhenready.js |  18 +--
 .../test/browser_toolbox_highlight.js         |  40 +++---
 .../framework/test/browser_toolbox_hosts.js   |  62 ++++-----
 .../test/browser_toolbox_hosts_size.js        |  24 ++--
 .../test/browser_toolbox_hosts_telemetry.js   |  26 ++--
 .../browser_toolbox_keyboard_navigation.js    |   4 +-
 .../test/browser_toolbox_minimize.js          |  48 +++----
 .../framework/test/browser_toolbox_options.js |  74 +++++------
 ...rowser_toolbox_options_disable_cache-01.js |  14 +--
 ...rowser_toolbox_options_disable_cache-02.js |  26 ++--
 .../browser_toolbox_options_disable_js.js     |  42 +++----
 .../framework/test/browser_toolbox_races.js   |  10 +-
 .../framework/test/browser_toolbox_ready.js   |  10 +-
 .../test/browser_toolbox_remoteness_change.js |  18 +--
 .../test/browser_toolbox_select_event.js      |  78 ++++++------
 ...owser_toolbox_selected_tool_unavailable.js |  12 +-
 .../browser_toolbox_selectionchanged_event.js |  16 +--
 .../browser_toolbox_sidebar_existing_tabs.js  |   8 +-
 .../browser_toolbox_sidebar_overflow_menu.js  |  10 +-
 .../test/browser_toolbox_split_console.js     |  30 ++---
 .../browser_toolbox_tabsswitch_shortcuts.js   |  22 ++--
 .../framework/test/browser_toolbox_target.js  |  12 +-
 .../browser_toolbox_theme_registration.js     |  26 ++--
 .../framework/test/browser_toolbox_toggle.js  |  38 +++---
 .../test/browser_toolbox_tool_ready.js        |  16 +--
 .../browser_toolbox_tool_remote_reopen.js     |  18 +--
 .../test/browser_toolbox_toolbar_overflow.js  |  24 ++--
 .../test/browser_toolbox_view_source_01.js    |  12 +-
 .../test/browser_toolbox_view_source_02.js    |  16 +--
 .../test/browser_toolbox_view_source_03.js    |  10 +-
 .../test/browser_toolbox_view_source_04.js    |  14 +--
 ...owser_toolbox_window_title_frame_select.js |  36 +++---
 devtools/client/framework/test/head.js        |   4 +-
 .../framework/test/helper_disable_cache.js    |  32 ++---
 .../test/test_browser_toolbox_debugger.js     |  18 +--
 .../framework/toolbox-highlighter-utils.js    | 107 ++++++++--------
 .../client/framework/toolbox-host-manager.js  |  13 +-
 devtools/client/framework/toolbox-init.js     |  15 +--
 devtools/client/framework/toolbox-options.js  |  21 ++--
 devtools/client/framework/toolbox.js          | 109 ++++++++--------
 devtools/client/inspector/test/shared-head.js |   4 +-
 .../jsonview/test/browser_json_refresh.js     |  10 +-
 .../test/browser_jsonview_bug_1380828.js      |  16 +--
 .../test/browser_jsonview_content_type.js     |   6 +-
 .../test/browser_jsonview_copy_headers.js     |  12 +-
 .../test/browser_jsonview_copy_json.js        |  10 +-
 .../test/browser_jsonview_copy_rawdata.js     |  16 +--
 .../test/browser_jsonview_csp_json.js         |   6 +-
 .../test/browser_jsonview_empty_object.js     |  18 +--
 .../test/browser_jsonview_encoding.js         |   8 +-
 .../jsonview/test/browser_jsonview_filter.js  |  12 +-
 .../test/browser_jsonview_ignore_charset.js   |   8 +-
 .../test/browser_jsonview_invalid_json.js     |   8 +-
 .../test/browser_jsonview_manifest.js         |   6 +-
 .../jsonview/test/browser_jsonview_nul.js     |   8 +-
 .../test/browser_jsonview_object-type.js      |  12 +-
 .../test/browser_jsonview_save_json.js        |  38 +++---
 .../jsonview/test/browser_jsonview_slash.js   |   6 +-
 .../jsonview/test/browser_jsonview_theme.js   |  12 +-
 .../test/browser_jsonview_valid_json.js       |  24 ++--
 devtools/client/memory/actions/allocations.js |   6 +-
 .../client/memory/actions/census-display.js   |   4 +-
 devtools/client/memory/actions/diffing.js     |  10 +-
 devtools/client/memory/actions/io.js          |  22 ++--
 .../client/memory/actions/label-display.js    |   4 +-
 devtools/client/memory/actions/refresh.js     |  12 +-
 devtools/client/memory/actions/snapshot.js    |  83 ++++++------
 devtools/client/memory/actions/task-cache.js  |   8 +-
 .../client/memory/actions/tree-map-display.js |   4 +-
 devtools/client/memory/actions/view.js        |   8 +-
 devtools/client/memory/initializer.js         |   9 +-
 devtools/client/memory/panel.js               |  15 +--
 ...rowser_memory_allocationStackDisplay_01.js |   8 +-
 .../browser/browser_memory_clear_snapshots.js |   6 +-
 .../test/browser/browser_memory_diff_01.js    |  14 +--
 .../browser/browser_memory_displays_01.js     |   8 +-
 .../browser_memory_dominator_trees_01.js      |  12 +-
 .../browser_memory_dominator_trees_02.js      |   8 +-
 .../test/browser/browser_memory_filter_01.js  |  12 +-
 .../browser/browser_memory_individuals_01.js  |   8 +-
 .../browser_memory_keyboard-snapshot-list.js  |  20 +--
 .../test/browser/browser_memory_keyboard.js   |  24 ++--
 .../browser_memory_no_allocation_stacks.js    |   6 +-
 .../browser/browser_memory_no_auto_expand.js  |   4 +-
 .../browser/browser_memory_percents_01.js     |   4 +-
 .../browser_memory_refresh_does_not_leak.js   |  14 +--
 .../test/browser/browser_memory_simple_01.js  |   8 +-
 ...ser_memory_transferHeapSnapshot_e10s_01.js |   6 +-
 .../browser/browser_memory_tree_map-01.js     |   2 +-
 .../browser/browser_memory_tree_map-02.js     |   2 +-
 devtools/client/memory/test/browser/head.js   |  28 ++---
 devtools/client/memory/test/chrome/head.js    |   1 +
 .../test/chrome/test_CensusTreeItem_01.html   |  12 +-
 .../chrome/test_DominatorTreeItem_01.html     |   6 +-
 .../test/chrome/test_DominatorTree_01.html    |   6 +-
 .../test/chrome/test_DominatorTree_02.html    |   6 +-
 .../test/chrome/test_DominatorTree_03.html    |   8 +-
 .../memory/test/chrome/test_Heap_01.html      |   6 +-
 .../memory/test/chrome/test_Heap_02.html      |  12 +-
 .../memory/test/chrome/test_Heap_03.html      |  10 +-
 .../memory/test/chrome/test_Heap_04.html      |  10 +-
 .../memory/test/chrome/test_Heap_05.html      |  12 +-
 .../memory/test/chrome/test_List_01.html      |   6 +-
 .../test/chrome/test_ShortestPaths_01.html    |   6 +-
 .../test/chrome/test_ShortestPaths_02.html    |   6 +-
 .../test/chrome/test_SnapshotListItem_01.html |   8 +-
 .../memory/test/chrome/test_Toolbar_01.html   |   8 +-
 .../memory/test/chrome/test_TreeMap_01.html   |   6 +-
 devtools/client/memory/test/unit/head.js      |  25 ++--
 .../unit/test_action-clear-snapshots_01.js    |  10 +-
 .../unit/test_action-clear-snapshots_02.js    |  12 +-
 .../unit/test_action-clear-snapshots_03.js    |  14 +--
 .../unit/test_action-clear-snapshots_04.js    |  12 +-
 .../unit/test_action-clear-snapshots_05.js    |  10 +-
 .../unit/test_action-clear-snapshots_06.js    |  12 +-
 .../test/unit/test_action-export-snapshot.js  |  14 +--
 .../memory/test/unit/test_action-filter-02.js |  16 +--
 .../memory/test/unit/test_action-filter-03.js |  14 +--
 .../test_action-import-snapshot-and-census.js |  12 +-
 ...t_action-import-snapshot-dominator-tree.js |   8 +-
 .../test/unit/test_action-select-snapshot.js  |   8 +-
 .../test_action-set-display-and-refresh-01.js |  28 ++---
 .../test_action-set-display-and-refresh-02.js |   6 +-
 .../test/unit/test_action-set-display.js      |   6 +-
 .../test/unit/test_action-take-census.js      |  14 +--
 .../test_action-take-snapshot-and-census.js   |   6 +-
 .../test/unit/test_action-take-snapshot.js    |   6 +-
 ...t_action-toggle-inverted-and-refresh-01.js |  16 +--
 ...t_action-toggle-inverted-and-refresh-02.js |  14 +--
 ...est_action-toggle-recording-allocations.js |  14 +--
 .../test/unit/test_action_diffing_01.js       |   6 +-
 .../test/unit/test_action_diffing_02.js       |   8 +-
 .../test/unit/test_action_diffing_03.js       |   8 +-
 .../test/unit/test_action_diffing_04.js       |  18 +--
 .../test/unit/test_action_diffing_05.js       |  24 ++--
 .../test/unit/test_dominator_trees_01.js      |  14 +--
 .../test/unit/test_dominator_trees_02.js      |  14 +--
 .../test/unit/test_dominator_trees_03.js      |  12 +-
 .../test/unit/test_dominator_trees_04.js      |  14 +--
 .../test/unit/test_dominator_trees_05.js      |  12 +-
 .../test/unit/test_dominator_trees_06.js      |  10 +-
 .../test/unit/test_dominator_trees_07.js      |  10 +-
 .../test/unit/test_dominator_trees_08.js      |  14 +--
 .../test/unit/test_dominator_trees_09.js      |  12 +-
 .../test/unit/test_dominator_trees_10.js      |  12 +-
 .../memory/test/unit/test_individuals_01.js   |  10 +-
 .../memory/test/unit/test_individuals_02.js   |  10 +-
 .../memory/test/unit/test_individuals_03.js   |  14 +--
 .../memory/test/unit/test_individuals_04.js   |  10 +-
 .../memory/test/unit/test_individuals_05.js   |  10 +-
 .../memory/test/unit/test_individuals_06.js   |  10 +-
 .../memory/test/unit/test_pop_view_01.js      |  12 +-
 .../unit/test_utils-get-snapshot-totals.js    |  12 +-
 .../test/browser_net_view-source-debugger.js  |   3 +-
 .../performance/components/test/head.js       |   1 +
 .../test/test_jit_optimizations_01.html       |   6 +-
 .../performance/modules/widgets/graphs.js     |  53 ++++----
 devtools/client/performance/panel.js          |  15 +--
 .../performance/performance-controller.js     |  69 +++++-----
 .../client/performance/performance-view.js    |  26 ++--
 .../test/browser_aaa-run-first-leaktest.js    |   6 +-
 .../test/browser_perf-button-states.js        |  22 ++--
 .../browser_perf-calltree-js-categories.js    |  16 +--
 .../test/browser_perf-calltree-js-columns.js  |  16 +--
 .../test/browser_perf-calltree-js-events.js   |  14 +--
 .../browser_perf-calltree-memory-columns.js   |  14 +--
 .../test/browser_perf-console-record-01.js    |  16 +--
 .../test/browser_perf-console-record-02.js    |  24 ++--
 .../test/browser_perf-console-record-03.js    |  22 ++--
 .../test/browser_perf-console-record-04.js    |  18 +--
 .../test/browser_perf-console-record-05.js    |  26 ++--
 .../test/browser_perf-console-record-06.js    |  28 ++---
 .../test/browser_perf-console-record-07.js    |  36 +++---
 .../test/browser_perf-console-record-08.js    |  50 ++++----
 .../test/browser_perf-console-record-09.js    |  24 ++--
 .../test/browser_perf-details-01-toggle.js    |  16 +--
 .../browser_perf-details-02-utility-fun.js    |  22 ++--
 ...ser_perf-details-03-without-allocations.js |  36 +++---
 ...browser_perf-details-04-toolbar-buttons.js |  22 ++--
 .../browser_perf-details-05-preserve-view.js  |  24 ++--
 ...r_perf-details-06-rerender-on-selection.js |  30 ++---
 .../browser_perf-details-07-bleed-events.js   |  26 ++--
 ...rowser_perf-details-render-00-waterfall.js |  14 +--
 ...wser_perf-details-render-01-js-calltree.js |  18 +--
 ...er_perf-details-render-02-js-flamegraph.js |  18 +--
 ..._perf-details-render-03-memory-calltree.js |  18 +--
 ...erf-details-render-04-memory-flamegraph.js |  18 +--
 .../performance/test/browser_perf-docload.js  |  14 +--
 .../performance/test/browser_perf-gc-snap.js  |  36 +++---
 .../test/browser_perf-highlighted.js          |  20 +--
 .../test/browser_perf-loading-01.js           |  14 +--
 .../test/browser_perf-loading-02.js           |  24 ++--
 .../test/browser_perf-marker-details.js       |  12 +-
 .../browser_perf-options-01-toggle-throw.js   |   8 +-
 ...rowser_perf-options-02-toggle-throw-alt.js |  12 +-
 .../browser_perf-options-03-toggle-meta.js    |   6 +-
 ...rowser_perf-options-enable-framerate-01.js |  14 +--
 ...rowser_perf-options-enable-framerate-02.js |  14 +--
 .../browser_perf-options-enable-memory-01.js  |  14 +--
 .../browser_perf-options-enable-memory-02.js  |  14 +--
 ..._perf-options-flatten-tree-recursion-01.js |  18 +--
 ..._perf-options-flatten-tree-recursion-02.js |  18 +--
 ...rowser_perf-options-invert-call-tree-01.js |  18 +--
 ...rowser_perf-options-invert-call-tree-02.js |  18 +--
 ...wser_perf-options-invert-flame-graph-01.js |  18 +--
 ...wser_perf-options-invert-flame-graph-02.js |  18 +--
 ...wser_perf-options-propagate-allocations.js |  12 +-
 ...browser_perf-options-propagate-profiler.js |  12 +-
 ...rowser_perf-options-show-idle-blocks-01.js |  18 +--
 ...rowser_perf-options-show-idle-blocks-02.js |  18 +--
 ...ser_perf-options-show-jit-optimizations.js |  44 +++----
 ...wser_perf-options-show-platform-data-01.js |  18 +--
 ...wser_perf-options-show-platform-data-02.js |  18 +--
 .../test/browser_perf-overview-render-01.js   |  12 +-
 .../test/browser_perf-overview-render-02.js   |  12 +-
 .../test/browser_perf-overview-render-03.js   |  16 +--
 .../test/browser_perf-overview-render-04.js   |  20 +--
 .../browser_perf-overview-selection-01.js     |  16 +--
 .../browser_perf-overview-selection-02.js     |  14 +--
 .../browser_perf-overview-selection-03.js     |  16 +--
 .../browser_perf-overview-time-interval.js    |  12 +-
 .../test/browser_perf-private-browsing.js     |  48 +++----
 .../test/browser_perf-range-changed-render.js |  30 ++---
 .../test/browser_perf-recording-notices-01.js |  10 +-
 .../test/browser_perf-recording-notices-02.js |  18 +--
 .../test/browser_perf-recording-notices-03.js |  40 +++---
 .../test/browser_perf-recording-notices-04.js |  18 +--
 .../test/browser_perf-recording-notices-05.js |   8 +-
 .../browser_perf-recording-selected-01.js     |  16 +--
 .../browser_perf-recording-selected-02.js     |  18 +--
 .../browser_perf-recording-selected-03.js     |  16 +--
 .../browser_perf-recording-selected-04.js     |  26 ++--
 .../test/browser_perf-recordings-clear-01.js  |  16 +--
 .../test/browser_perf-recordings-clear-02.js  |  20 +--
 .../test/browser_perf-recordings-io-01.js     |  28 ++---
 .../test/browser_perf-recordings-io-02.js     |  10 +-
 .../test/browser_perf-recordings-io-03.js     |  12 +-
 .../test/browser_perf-recordings-io-04.js     |  18 +--
 .../test/browser_perf-recordings-io-05.js     |  24 ++--
 .../test/browser_perf-recordings-io-06.js     |  16 +--
 .../performance/test/browser_perf-refresh.js  |  14 +--
 .../performance/test/browser_perf-states.js   |  14 +--
 .../test/browser_perf-telemetry-01.js         |  14 +--
 .../test/browser_perf-telemetry-02.js         |  18 +--
 .../test/browser_perf-telemetry-03.js         |  18 +--
 .../test/browser_perf-telemetry-04.js         |  16 +--
 .../test/browser_perf-theme-toggle.js         |  22 ++--
 .../test/browser_perf-tree-abstract-01.js     |  14 +--
 .../test/browser_perf-tree-abstract-02.js     |   4 +-
 .../test/browser_perf-tree-abstract-03.js     |   4 +-
 .../test/browser_perf-tree-abstract-04.js     |   6 +-
 .../test/browser_perf-tree-abstract-05.js     |   4 +-
 .../test/browser_perf-tree-view-06.js         |   6 +-
 .../test/browser_perf-tree-view-11.js         |  18 +--
 .../test/browser_perf-ui-recording.js         |  16 +--
 .../test/browser_timeline-filters-01.js       |  24 ++--
 .../test/browser_timeline-filters-02.js       |  16 +--
 .../browser_timeline-waterfall-background.js  |  12 +-
 .../browser_timeline-waterfall-generic.js     |  14 +--
 .../browser_timeline-waterfall-rerender.js    |  18 +--
 .../browser_timeline-waterfall-sidebar.js     |  12 +-
 .../browser_timeline-waterfall-workers.js     |  12 +-
 .../performance/test/helpers/panel-utils.js   |  58 ++++-----
 .../test/helpers/profiler-mm-utils.js         |  13 +-
 .../performance/test/helpers/tab-utils.js     |   4 +-
 .../performance/test/helpers/wait-utils.js    |   7 +-
 .../views/details-abstract-subview.js         |   6 +-
 .../views/details-js-flamegraph.js            |  12 +-
 .../views/details-memory-flamegraph.js        |  12 +-
 devtools/client/performance/views/details.js  |  30 ++---
 devtools/client/performance/views/overview.js |  46 +++----
 .../client/performance/views/recordings.js    |   4 +-
 devtools/client/performance/views/toolbar.js  |   6 +-
 .../test/browser_scratchpad_autocomplete.js   |  11 +-
 .../test/browser_scratchpad_close_toolbox.js  |  11 +-
 .../test/browser_scratchpad_contexts.js       |  30 ++---
 ...wser_scratchpad_disable_view_menu_items.js |  15 +--
 .../test/browser_scratchpad_execute_print.js  |  26 ++--
 .../browser_scratchpad_inspect_primitives.js  |  15 +--
 devtools/client/scratchpad/test/head.js       |  10 +-
 devtools/client/shadereditor/shadereditor.js  |  22 ++--
 .../test/browser_se_aaa_run_first_leaktest.js |   6 +-
 .../shadereditor/test/browser_se_bfcache.js   |  30 ++---
 .../test/browser_se_editors-contents.js       |  12 +-
 .../test/browser_se_editors-error-gutter.js   |  28 ++---
 .../test/browser_se_editors-error-tooltip.js  |  14 +--
 .../test/browser_se_editors-lazy-init.js      |  16 +--
 .../shadereditor/test/browser_se_first-run.js |  10 +-
 .../test/browser_se_navigation.js             |  16 +--
 .../test/browser_se_programs-blackbox-01.js   |  92 +++++++-------
 .../test/browser_se_programs-blackbox-02.js   |  32 ++---
 .../test/browser_se_programs-cache.js         |  24 ++--
 .../test/browser_se_programs-highlight-01.js  |  60 ++++-----
 .../test/browser_se_programs-highlight-02.js  |  24 ++--
 .../test/browser_se_programs-list.js          |  22 ++--
 .../test/browser_se_shaders-edit-01.js        |  34 ++---
 .../test/browser_se_shaders-edit-02.js        |  28 ++---
 .../test/browser_se_shaders-edit-03.js        |  38 +++---
 .../test/browser_webgl-actor-test-01.js       |   6 +-
 .../test/browser_webgl-actor-test-02.js       |   8 +-
 .../test/browser_webgl-actor-test-03.js       |  12 +-
 .../test/browser_webgl-actor-test-04.js       |  12 +-
 .../test/browser_webgl-actor-test-05.js       |  16 +--
 .../test/browser_webgl-actor-test-06.js       |  62 ++++-----
 .../test/browser_webgl-actor-test-07.js       |  46 +++----
 .../test/browser_webgl-actor-test-08.js       |  28 ++---
 .../test/browser_webgl-actor-test-09.js       |  44 +++----
 .../test/browser_webgl-actor-test-10.js       |  32 ++---
 .../test/browser_webgl-actor-test-11.js       |  12 +-
 .../test/browser_webgl-actor-test-12.js       |  16 +--
 .../test/browser_webgl-actor-test-13.js       |  64 +++++-----
 .../test/browser_webgl-actor-test-14.js       |  40 +++---
 .../test/browser_webgl-actor-test-15.js       | 118 +++++++++---------
 .../test/browser_webgl-actor-test-16.js       | 102 +++++++--------
 .../test/browser_webgl-actor-test-17.js       |  46 +++----
 .../test/browser_webgl-actor-test-18.js       |  14 +--
 devtools/client/shadereditor/test/head.js     |  34 +++--
 .../browser/browser_notification_box_basic.js |   4 +-
 .../shared/components/test/mochitest/head.js  |   1 +
 .../test/mochitest/test_HSplitBox_01.html     |   4 +-
 .../test/mochitest/test_frame_01.html         |  46 +++----
 .../test/mochitest/test_frame_02.html         |   4 +-
 .../mochitest/test_notification_box_01.html   |   4 +-
 .../mochitest/test_notification_box_02.html   |   4 +-
 .../mochitest/test_notification_box_03.html   |   4 +-
 .../test/mochitest/test_sidebar_toggle.html   |   6 +-
 .../test_stack-trace-source-maps.html         |   4 +-
 .../test/mochitest/test_stack-trace.html      |   4 +-
 .../mochitest/test_tabs_accessibility.html    |  10 +-
 .../test/mochitest/test_tabs_menu.html        |  14 +--
 .../test/mochitest/test_tree_01.html          |   6 +-
 .../test/mochitest/test_tree_02.html          |   6 +-
 .../test/mochitest/test_tree_03.html          |   4 +-
 .../test/mochitest/test_tree_04.html          |  12 +-
 .../test/mochitest/test_tree_06.html          |  26 ++--
 .../test/mochitest/test_tree_07.html          |   8 +-
 .../test/mochitest/test_tree_08.html          |   6 +-
 .../test/mochitest/test_tree_09.html          |   8 +-
 .../test/mochitest/test_tree_10.html          |   4 +-
 .../test/mochitest/test_tree_11.html          |   8 +-
 devtools/client/shared/developer-toolbar.js   |  23 ++--
 devtools/client/shared/doorhanger.js          |   9 +-
 .../test/test_middleware-task-01.js           |  12 +-
 .../test/test_middleware-task-02.js           |  14 +--
 .../test/test_middleware-task-03.js           |   4 +-
 .../client/shared/test/browser_css_angle.js   |   6 +-
 .../client/shared/test/browser_css_color.js   |   6 +-
 .../shared/test/browser_cubic-bezier-01.js    |   4 +-
 .../shared/test/browser_cubic-bezier-02.js    |  38 +++---
 .../shared/test/browser_cubic-bezier-03.js    |  18 +--
 .../shared/test/browser_cubic-bezier-04.js    |   4 +-
 .../shared/test/browser_cubic-bezier-05.js    |   4 +-
 .../shared/test/browser_cubic-bezier-06.js    |  16 +--
 .../shared/test/browser_cubic-bezier-07.js    |  18 +--
 .../client/shared/test/browser_devices.js     |   8 +-
 .../shared/test/browser_filter-editor-01.js   |   4 +-
 .../shared/test/browser_filter-editor-02.js   |   4 +-
 .../shared/test/browser_filter-editor-03.js   |   4 +-
 .../shared/test/browser_filter-editor-04.js   |   4 +-
 .../shared/test/browser_filter-editor-05.js   |   4 +-
 .../shared/test/browser_filter-editor-06.js   |   4 +-
 .../shared/test/browser_filter-editor-07.js   |   4 +-
 .../shared/test/browser_filter-editor-08.js   |   4 +-
 .../shared/test/browser_filter-editor-09.js   |   4 +-
 .../shared/test/browser_filter-editor-10.js   |   4 +-
 .../shared/test/browser_filter-presets-01.js  |  24 ++--
 .../shared/test/browser_filter-presets-02.js  |  12 +-
 .../shared/test/browser_filter-presets-03.js  |  12 +-
 .../shared/test/browser_flame-graph-01.js     |  14 +--
 .../shared/test/browser_flame-graph-02.js     |  14 +--
 .../shared/test/browser_flame-graph-03a.js    |  14 +--
 .../shared/test/browser_flame-graph-03b.js    |  14 +--
 .../shared/test/browser_flame-graph-03c.js    |  14 +--
 .../shared/test/browser_flame-graph-04.js     |  14 +--
 .../shared/test/browser_flame-graph-05.js     |  24 ++--
 .../test/browser_flame-graph-utils-01.js      |   8 +-
 .../test/browser_flame-graph-utils-02.js      |   8 +-
 .../test/browser_flame-graph-utils-03.js      |   8 +-
 .../test/browser_flame-graph-utils-04.js      |   8 +-
 .../test/browser_flame-graph-utils-05.js      |   8 +-
 .../test/browser_flame-graph-utils-06.js      |   8 +-
 .../client/shared/test/browser_graphs-01.js   |  14 +--
 .../client/shared/test/browser_graphs-02.js   |  14 +--
 .../client/shared/test/browser_graphs-03.js   |  26 ++--
 .../client/shared/test/browser_graphs-04.js   |  14 +--
 .../client/shared/test/browser_graphs-05.js   |  14 +--
 .../client/shared/test/browser_graphs-06.js   |  14 +--
 .../client/shared/test/browser_graphs-07a.js  |  18 +--
 .../client/shared/test/browser_graphs-07b.js  |  14 +--
 .../client/shared/test/browser_graphs-07c.js  |  14 +--
 .../client/shared/test/browser_graphs-07d.js  |  14 +--
 .../client/shared/test/browser_graphs-07e.js  |  14 +--
 .../client/shared/test/browser_graphs-08.js   |  14 +--
 .../client/shared/test/browser_graphs-09a.js  |  18 +--
 .../client/shared/test/browser_graphs-09b.js  |  18 +--
 .../client/shared/test/browser_graphs-09c.js  |  18 +--
 .../client/shared/test/browser_graphs-09d.js  |  18 +--
 .../client/shared/test/browser_graphs-09e.js  |  22 ++--
 .../client/shared/test/browser_graphs-09f.js  |  26 ++--
 .../client/shared/test/browser_graphs-10a.js  |  22 ++--
 .../client/shared/test/browser_graphs-10b.js  |  22 ++--
 .../client/shared/test/browser_graphs-10c.js  |  22 ++--
 .../client/shared/test/browser_graphs-11a.js  |  14 +--
 .../client/shared/test/browser_graphs-11b.js  |  32 ++---
 .../client/shared/test/browser_graphs-12.js   |  18 +--
 .../client/shared/test/browser_graphs-13.js   |  14 +--
 .../client/shared/test/browser_graphs-14.js   |  18 +--
 .../client/shared/test/browser_graphs-15.js   |  18 +--
 .../client/shared/test/browser_graphs-16.js   |  14 +--
 .../shared/test/browser_html_tooltip-01.js    |  20 +--
 .../shared/test/browser_html_tooltip-02.js    |  64 +++++-----
 .../shared/test/browser_html_tooltip-03.js    |  58 ++++-----
 .../shared/test/browser_html_tooltip-04.js    |  40 +++---
 .../shared/test/browser_html_tooltip-05.js    |  40 +++---
 .../test/browser_html_tooltip_arrow-01.js     |  18 +--
 .../test/browser_html_tooltip_arrow-02.js     |  16 +--
 .../browser_html_tooltip_consecutive-show.js  |   6 +-
 .../shared/test/browser_html_tooltip_hover.js |  20 +--
 .../test/browser_html_tooltip_offset.js       |  16 +--
 .../shared/test/browser_html_tooltip_rtl.js   |  24 ++--
 .../browser_html_tooltip_variable-height.js   |  18 +--
 .../test/browser_html_tooltip_width-auto.js   |  16 +--
 .../test/browser_html_tooltip_xul-wrapper.js  |  14 +--
 .../shared/test/browser_inplace-editor-01.js  |  18 +--
 .../shared/test/browser_inplace-editor-02.js  |  10 +-
 .../browser_inplace-editor_autocomplete_01.js |  14 +--
 .../browser_inplace-editor_autocomplete_02.js |  14 +--
 ...nplace-editor_autocomplete_css_variable.js |  14 +--
 ...wser_inplace-editor_autocomplete_offset.js |  14 +--
 .../test/browser_inplace-editor_maxwidth.js   |  12 +-
 .../shared/test/browser_key_shortcuts.js      | 106 ++++++++--------
 .../shared/test/browser_layoutHelpers.js      |   4 +-
 .../shared/test/browser_options-view-01.js    |  24 ++--
 .../shared/test/browser_outputparser.js       |  12 +-
 devtools/client/shared/test/browser_poller.js |  28 ++---
 .../client/shared/test/browser_spectrum.js    |  14 +--
 .../shared/test/browser_tableWidget_basic.js  |   6 +-
 ...rowser_tableWidget_keyboard_interaction.js |  38 +++---
 .../browser_tableWidget_mouse_interaction.js  |  42 +++----
 .../browser_telemetry_button_eyedropper.js    |  14 +--
 .../browser_telemetry_button_paintflashing.js |  22 ++--
 .../browser_telemetry_button_responsive.js    |  22 ++--
 .../browser_telemetry_button_scratchpad.js    |  18 +--
 .../shared/test/browser_telemetry_sidebar.js  |  12 +-
 .../shared/test/browser_telemetry_toolbox.js  |   6 +-
 ...er_telemetry_toolboxtabs_canvasdebugger.js |   6 +-
 ...browser_telemetry_toolboxtabs_inspector.js |   6 +-
 ...rowser_telemetry_toolboxtabs_jsdebugger.js |   6 +-
 ...rowser_telemetry_toolboxtabs_jsprofiler.js |   6 +-
 ...rowser_telemetry_toolboxtabs_netmonitor.js |   6 +-
 .../browser_telemetry_toolboxtabs_options.js  |   6 +-
 ...wser_telemetry_toolboxtabs_shadereditor.js |   6 +-
 .../browser_telemetry_toolboxtabs_storage.js  |   6 +-
 ...owser_telemetry_toolboxtabs_styleeditor.js |   6 +-
 ...er_telemetry_toolboxtabs_webaudioeditor.js |   6 +-
 ...rowser_telemetry_toolboxtabs_webconsole.js |   6 +-
 .../shared/test/browser_templater_basic.js    |   8 +-
 .../shared/test/browser_theme_switching.js    |   6 +-
 .../shared/test/browser_toolbar_basic.js      |  16 +--
 .../shared/test/browser_toolbar_tooltip.js    |  26 ++--
 .../shared/test/browser_treeWidget_basic.js   |   6 +-
 .../browser_treeWidget_mouse_interaction.js   |  16 +--
 .../client/shared/test/frame-script-utils.js  |   7 +-
 devtools/client/shared/test/head.js           |  26 ++--
 .../client/shared/test/helper_html_tooltip.js |   8 +-
 .../shared/test/helper_inplace_editor.js      |  12 +-
 devtools/client/shared/test/shared-head.js    |  61 ++++-----
 .../client/shared/test/test-actor-registry.js |  35 +++---
 devtools/client/shared/test/test-actor.js     | 101 +++++++--------
 devtools/client/shared/view-source.js         |  34 ++---
 devtools/client/shared/widgets/ColorWidget.js |   7 +-
 devtools/client/shared/widgets/FlameGraph.js  |  13 +-
 devtools/client/shared/widgets/Graphs.js      |  21 ++--
 .../client/shared/widgets/LineGraphWidget.js  |   7 +-
 .../client/shared/widgets/VariablesView.jsm   |  15 +--
 .../shared/widgets/tooltip/HTMLTooltip.js     |  13 +-
 .../shared/widgets/tooltip/TooltipToggle.js   |   8 +-
 .../browser_editor_autocomplete_events.js     |  44 +++----
 .../test/browser_editor_find_again.js         |  24 ++--
 .../test/browser_editor_script_injection.js   |   8 +-
 .../storage/test/browser_storage_basic.js     |  12 +-
 .../browser_storage_basic_usercontextid_1.js  |  12 +-
 .../browser_storage_basic_usercontextid_2.js  |  12 +-
 .../browser_storage_basic_with_fragment.js    |  12 +-
 .../test/browser_storage_cache_delete.js      |  14 +--
 .../test/browser_storage_cache_error.js       |   8 +-
 .../test/browser_storage_cookies_add.js       |  16 +--
 .../browser_storage_cookies_delete_all.js     |  28 ++---
 .../test/browser_storage_cookies_domain.js    |   8 +-
 .../browser_storage_cookies_domain_port.js    |   8 +-
 .../test/browser_storage_cookies_edit.js      |  20 +--
 .../browser_storage_cookies_edit_keyboard.js  |  22 ++--
 .../test/browser_storage_cookies_samesite.js  |   8 +-
 .../browser_storage_cookies_tab_navigation.js |   8 +-
 .../storage/test/browser_storage_delete.js    |  12 +-
 .../test/browser_storage_delete_all.js        |  16 +--
 .../test/browser_storage_delete_tree.js       |  16 +--
 .../browser_storage_delete_usercontextid.js   |  24 ++--
 .../browser_storage_dom_cache_disabled.js     |   8 +-
 ...browser_storage_dynamic_updates_cookies.js |  60 ++++-----
 ...er_storage_dynamic_updates_localStorage.js |  28 ++---
 ..._storage_dynamic_updates_sessionStorage.js |  34 ++---
 .../browser_storage_empty_objectstores.js     |  12 +-
 .../test/browser_storage_indexeddb_delete.js  |  16 +--
 ...rowser_storage_indexeddb_delete_blocked.js |  24 ++--
 ...owser_storage_indexeddb_duplicate_names.js |   8 +-
 .../test/browser_storage_localstorage_add.js  |  16 +--
 .../test/browser_storage_localstorage_edit.js |  20 +--
 .../browser_storage_localstorage_error.js     |   8 +-
 .../storage/test/browser_storage_overflow.js  |  16 +--
 .../storage/test/browser_storage_search.js    |   8 +-
 .../browser_storage_search_keyboard_trap.js   |  10 +-
 .../browser_storage_sessionstorage_add.js     |  16 +--
 .../browser_storage_sessionstorage_edit.js    |  20 +--
 .../storage/test/browser_storage_sidebar.js   |  10 +-
 .../test/browser_storage_sidebar_toggle.js    |  10 +-
 .../test/browser_storage_sidebar_update.js    |  14 +--
 .../storage/test/browser_storage_values.js    |  12 +-
 devtools/client/storage/test/head.js          |  76 +++++------
 .../storage/test/storage-complex-values.html  |  22 ++--
 .../test/storage-empty-objectstores.html      |  16 +--
 .../test/storage-idb-delete-blocked.html      |  14 +--
 .../storage-indexeddb-duplicate-names.html    |  14 +--
 .../test/storage-listings-usercontextid.html  |  18 +--
 .../test/storage-listings-with-fragment.html  |  20 +--
 .../client/storage/test/storage-listings.html |  20 +--
 .../storage-secured-iframe-usercontextid.html |  24 ++--
 .../storage/test/storage-secured-iframe.html  |  26 ++--
 devtools/client/styleeditor/StyleEditorUI.jsm |  55 ++++----
 .../client/styleeditor/StyleSheetEditor.jsm   |   9 +-
 .../client/styleeditor/styleeditor-panel.js   |  11 +-
 .../browser_styleeditor_add_stylesheet.js     |   8 +-
 ...owser_styleeditor_autocomplete-disabled.js |   6 +-
 .../test/browser_styleeditor_autocomplete.js  |  16 +--
 .../test/browser_styleeditor_bom.js           |   6 +-
 .../browser_styleeditor_bug_740541_iframes.js |   4 +-
 ...ser_styleeditor_bug_851132_middle_click.js |  16 +--
 .../test/browser_styleeditor_bug_870339.js    |   6 +-
 .../test/browser_styleeditor_cmd_edit.js      |  16 +--
 .../test/browser_styleeditor_enabled.js       |  18 +--
 ...owser_styleeditor_fetch-from-netmonitor.js |  16 +--
 .../test/browser_styleeditor_filesave.js      |  14 +--
 .../browser_styleeditor_highlight-selector.js |   6 +-
 .../test/browser_styleeditor_import.js        |   6 +-
 .../test/browser_styleeditor_import_rule.js   |   4 +-
 .../test/browser_styleeditor_init.js          |   4 +-
 ...owser_styleeditor_inline_friendly_names.js |  16 +--
 .../test/browser_styleeditor_loading.js       |   4 +-
 ...ser_styleeditor_loading_with_containers.js |  10 +-
 .../test/browser_styleeditor_media_sidebar.js |  26 ++--
 ...browser_styleeditor_media_sidebar_links.js |  30 ++---
 ...er_styleeditor_media_sidebar_sourcemaps.js |   6 +-
 .../browser_styleeditor_missing_stylesheet.js |   4 +-
 .../test/browser_styleeditor_navigate.js      |  10 +-
 .../test/browser_styleeditor_new.js           |  16 +--
 .../test/browser_styleeditor_nostyle.js       |   4 +-
 .../test/browser_styleeditor_opentab.js       |  12 +-
 .../test/browser_styleeditor_pretty.js        |   8 +-
 ...browser_styleeditor_private_perwindowpb.js |  14 +--
 .../test/browser_styleeditor_reload.js        |  10 +-
 .../test/browser_styleeditor_scroll.js        |  22 ++--
 .../browser_styleeditor_selectstylesheet.js   |   6 +-
 .../browser_styleeditor_sourcemap_large.js    |   6 +-
 .../browser_styleeditor_sourcemap_watching.js |  30 ++---
 .../test/browser_styleeditor_sourcemaps.js    |  18 +--
 .../browser_styleeditor_sourcemaps_inline.js  |  14 +--
 .../test/browser_styleeditor_sv_keynav.js     |   8 +-
 .../test/browser_styleeditor_sv_resize.js     |   8 +-
 .../test/browser_styleeditor_sync.js          |  30 ++---
 .../browser_styleeditor_syncAddProperty.js    |  16 +--
 .../test/browser_styleeditor_syncAddRule.js   |  14 +--
 .../browser_styleeditor_syncAlreadyOpen.js    |  20 +--
 .../browser_styleeditor_syncEditSelector.js   |  16 +--
 .../browser_styleeditor_syncIntoRuleView.js   |  16 +--
 .../browser_styleeditor_transition_rule.js    |  12 +-
 .../test/browser_styleeditor_xul.js           |   6 +-
 devtools/client/styleeditor/test/head.js      |  36 +++---
 devtools/client/webaudioeditor/controller.js  |  44 +++----
 devtools/client/webaudioeditor/includes.js    |   1 +
 ...er_audionode-actor-add-automation-event.js |  30 ++---
 .../test/browser_audionode-actor-bypass.js    |  22 ++--
 .../browser_audionode-actor-bypassable.js     |   8 +-
 ..._audionode-actor-connectnode-disconnect.js |  12 +-
 .../browser_audionode-actor-connectparam.js   |  12 +-
 ..._audionode-actor-get-automation-data-01.js |  26 ++--
 ..._audionode-actor-get-automation-data-02.js |  20 +--
 ..._audionode-actor-get-automation-data-03.js |  20 +--
 ...browser_audionode-actor-get-param-flags.js |  12 +-
 .../browser_audionode-actor-get-params-01.js  |  14 +--
 .../browser_audionode-actor-get-params-02.js  |  14 +--
 .../browser_audionode-actor-get-set-param.js  |  26 ++--
 .../test/browser_audionode-actor-source.js    |   8 +-
 .../test/browser_audionode-actor-type.js      |   8 +-
 .../test/browser_callwatcher-01.js            |   8 +-
 .../test/browser_callwatcher-02.js            |  12 +-
 .../test/browser_wa_automation-view-01.js     |  14 +--
 .../test/browser_wa_automation-view-02.js     |  12 +-
 .../test/browser_wa_controller-01.js          |   8 +-
 .../test/browser_wa_destroy-node-01.js        |  12 +-
 .../test/browser_wa_first-run.js              |  10 +-
 .../test/browser_wa_graph-click.js            |  18 +--
 .../test/browser_wa_graph-markers.js          |   8 +-
 .../test/browser_wa_graph-render-01.js        |  10 +-
 .../test/browser_wa_graph-render-02.js        |   8 +-
 .../test/browser_wa_graph-render-03.js        |  12 +-
 .../test/browser_wa_graph-render-04.js        |   8 +-
 .../test/browser_wa_graph-render-05.js        |  12 +-
 .../test/browser_wa_graph-render-06.js        |   8 +-
 .../test/browser_wa_graph-selected.js         |  12 +-
 .../test/browser_wa_graph-zoom.js             |  10 +-
 .../test/browser_wa_inspector-bypass-01.js    |  26 ++--
 .../test/browser_wa_inspector-toggle.js       |  16 +--
 .../test/browser_wa_inspector-width.js        |  16 +--
 .../test/browser_wa_inspector.js              |  12 +-
 .../test/browser_wa_navigate.js               |  10 +-
 .../browser_wa_properties-view-edit-01.js     |  30 ++---
 .../browser_wa_properties-view-edit-02.js     |  14 +--
 .../browser_wa_properties-view-media-nodes.js |  16 +--
 ...owser_wa_properties-view-params-objects.js |  12 +-
 .../test/browser_wa_properties-view-params.js |  14 +--
 .../test/browser_wa_properties-view.js        |  12 +-
 .../test/browser_wa_reset-01.js               |  14 +--
 .../test/browser_wa_reset-02.js               |  10 +-
 .../test/browser_wa_reset-03.js               |  14 +--
 .../test/browser_wa_reset-04.js               |  14 +--
 ...browser_webaudio-actor-automation-event.js |   8 +-
 .../browser_webaudio-actor-connect-param.js   |   8 +-
 .../browser_webaudio-actor-destroy-node.js    |  10 +-
 .../test/browser_webaudio-actor-simple.js     |   8 +-
 devtools/client/webaudioeditor/test/head.js   |  20 +--
 .../client/webaudioeditor/views/automation.js |  14 +--
 .../client/webaudioeditor/views/inspector.js  |   4 +-
 .../client/webaudioeditor/views/properties.js |  12 +-
 devtools/client/webconsole/console-output.js  |  33 ++---
 .../net/test/mochitest/browser_net_basic.js   |   6 +-
 .../net/test/mochitest/browser_net_cookies.js |   8 +-
 .../net/test/mochitest/browser_net_headers.js |  10 +-
 .../net/test/mochitest/browser_net_params.js  |  16 +--
 .../net/test/mochitest/browser_net_post.js    |  24 ++--
 .../test/mochitest/browser_net_response.js    |  24 ++--
 .../webconsole/net/test/mochitest/head.js     |  28 ++---
 .../new-console-output/test/chrome/head.js    |   2 +
 ...wser_webconsole_check_stubs_console_api.js |   6 +-
 ...wser_webconsole_check_stubs_css_message.js |   6 +-
 ...ebconsole_check_stubs_evaluation_result.js |   6 +-
 ...er_webconsole_check_stubs_network_event.js |   6 +-
 ...owser_webconsole_check_stubs_page_error.js |   6 +-
 ...ser_webconsole_update_stubs_console_api.js |   6 +-
 ...ser_webconsole_update_stubs_css_message.js |   6 +-
 ...bconsole_update_stubs_evaluation_result.js |   6 +-
 ...r_webconsole_update_stubs_network_event.js |   6 +-
 ...wser_webconsole_update_stubs_page_error.js |   6 +-
 .../test/fixtures/stub-generators/head.js     |  48 +++----
 .../mochitest/browser_console_clear_method.js |  14 +--
 ...ser_console_webconsole_private_browsing.js |   2 +-
 .../browser_webconsole_closure_inspection.js  |   2 +-
 .../browser_webconsole_console_table.js       |   8 +-
 .../mochitest/browser_webconsole_file_uri.js  |  10 +-
 .../test/mochitest/browser_webconsole_init.js |   8 +-
 ...nsole_input_field_focus_on_panel_select.js |  10 +-
 ...ser_webconsole_location_scratchpad_link.js |  14 +--
 .../mochitest/browser_webconsole_loglimit.js  |   4 +-
 .../browser_webconsole_longstring_expand.js   |  14 +--
 .../browser_webconsole_longstring_hang.js     |  10 +-
 .../browser_webconsole_message_categories.js  |   2 +-
 ...nspector_while_debugging_and_inspecting.js |   2 +-
 .../browser_webconsole_optimized_out_vars.js  |   2 +-
 ...ole_stacktrace_location_scratchpad_link.js |  14 +--
 devtools/client/webide/content/webide.js      |  45 +++----
 devtools/client/webide/modules/app-manager.js |  45 +++----
 .../client/webide/modules/app-validator.js    |   9 +-
 .../client/webide/modules/project-list.js     |  19 +--
 .../client/webide/modules/runtime-list.js     |   1 +
 devtools/client/webide/modules/tab-store.js   |   7 +-
 devtools/client/webide/test/browser_tabs.js   |  38 +++---
 .../client/webide/test/device_front_shared.js |  18 +--
 devtools/client/webide/test/head.js           |  15 +--
 devtools/client/webide/test/test_addons.html  |  12 +-
 .../webide/test/test_autoconnect_runtime.html |  26 ++--
 .../webide/test/test_autoselect_project.html  |  34 ++---
 devtools/client/webide/test/test_basic.html   |  12 +-
 .../webide/test/test_device_preferences.html  |  20 +--
 .../webide/test/test_device_runtime.html      |  16 +--
 .../webide/test/test_duplicate_import.html    |  38 +++---
 .../webide/test/test_fullscreenToolbox.html   |  16 +--
 devtools/client/webide/test/test_import.html  |  30 ++---
 .../webide/test/test_manifestUpdate.html      |  32 ++---
 devtools/client/webide/test/test_newapp.html  |  12 +-
 devtools/client/webide/test/test_runtime.html |  44 +++----
 devtools/client/webide/test/test_toolbox.html |  30 ++---
 devtools/client/webide/test/test_zoom.html    |  12 +-
 785 files changed, 6722 insertions(+), 6681 deletions(-)

diff --git a/devtools/client/aboutdebugging/modules/worker.js b/devtools/client/aboutdebugging/modules/worker.js
index a04ca397deb7..1623088c638f 100644
--- a/devtools/client/aboutdebugging/modules/worker.js
+++ b/devtools/client/aboutdebugging/modules/worker.js
@@ -4,6 +4,8 @@
 
 "use strict";
 
+const { Task } = require("devtools/shared/task");
+
 loader.lazyRequireGetter(this, "gDevTools",
   "devtools/client/framework/devtools", true);
 loader.lazyRequireGetter(this, "TargetFactory",
@@ -40,28 +42,28 @@ exports.debugWorker = function (client, workerActor) {
  *         - {Array} workers
  *           Array of WorkerActor forms
  */
-exports.getWorkerForms = async function (client) {
+exports.getWorkerForms = Task.async(function* (client) {
   let registrations = [];
   let workers = [];
 
   try {
     // List service worker registrations
     ({ registrations } =
-      await client.mainRoot.listServiceWorkerRegistrations());
+      yield client.mainRoot.listServiceWorkerRegistrations());
 
     // List workers from the Parent process
-    ({ workers } = await client.mainRoot.listWorkers());
+    ({ workers } = yield client.mainRoot.listWorkers());
 
     // And then from the Child processes
-    let { processes } = await client.mainRoot.listProcesses();
+    let { processes } = yield client.mainRoot.listProcesses();
     for (let process of processes) {
       // Ignore parent process
       if (process.parent) {
         continue;
       }
-      let { form } = await client.getProcess(process.id);
+      let { form } = yield client.getProcess(process.id);
       let processActor = form.actor;
-      let response = await client.request({
+      let response = yield client.request({
         to: processActor,
         type: "listWorkers"
       });
@@ -72,4 +74,4 @@ exports.getWorkerForms = async function (client) {
   }
 
   return { registrations, workers };
-};
+});
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_bootstrapped.js b/devtools/client/aboutdebugging/test/browser_addons_debug_bootstrapped.js
index 51552f7de260..688d286c1892 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_bootstrapped.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_bootstrapped.js
@@ -15,8 +15,8 @@ const ADDON_NAME = "test-devtools";
 
 const { BrowserToolboxProcess } = ChromeUtils.import("resource://devtools/client/framework/ToolboxProcess.jsm", {});
 
-add_task(async function () {
-  await new Promise(resolve => {
+add_task(function* () {
+  yield new Promise(resolve => {
     let options = {"set": [
       // Force enabling of addons debugging
       ["devtools.chrome.enabled", true],
@@ -29,9 +29,9 @@ add_task(async function () {
     SpecialPowers.pushPrefEnv(options, resolve);
   });
 
-  let { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
-  await installAddon({
+  let { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: ADDON_NAME,
@@ -77,12 +77,12 @@ add_task(async function () {
 
   debugBtn.click();
 
-  await onCustomMessage;
+  yield onCustomMessage;
   ok(true, "Received the notification message from the bootstrap.js function");
 
-  await onToolboxClose;
+  yield onToolboxClose;
   ok(true, "Addon toolbox closed");
 
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
-  await closeAboutDebugging(tab);
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_info.js b/devtools/client/aboutdebugging/test/browser_addons_debug_info.js
index fc4e1394710c..a96c3debb3b2 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_info.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_info.js
@@ -10,13 +10,13 @@ function testFilePath(container, expectedFilePath) {
   is(filePath.previousElementSibling.textContent, "Location", "file path has label");
 }
 
-add_task(async function testLegacyAddon() {
+add_task(function* testLegacyAddon() {
   let addonId = "test-devtools@mozilla.org";
   let addonName = "test-devtools";
-  let { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+  let { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
-  await installAddon({
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: addonName,
@@ -25,18 +25,18 @@ add_task(async function testLegacyAddon() {
   let container = document.querySelector(`[data-addon-id="${addonId}"]`);
   testFilePath(container, "browser/devtools/client/aboutdebugging/test/addons/unpacked/");
 
-  await uninstallAddon({document, id: addonId, name: addonName});
+  yield uninstallAddon({document, id: addonId, name: addonName});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function testWebExtension() {
+add_task(function* testWebExtension() {
   let addonId = "test-devtools-webextension-nobg@mozilla.org";
   let addonName = "test-devtools-webextension-nobg";
-  let { tab, document } = await openAboutDebugging("addons");
+  let { tab, document } = yield openAboutDebugging("addons");
 
-  await waitForInitialAddonList(document);
-  await installAddon({
+  yield waitForInitialAddonList(document);
+  yield installAddon({
     document,
     path: "addons/test-devtools-webextension-nobg/manifest.json",
     name: addonName,
@@ -55,17 +55,17 @@ add_task(async function testWebExtension() {
   let manifestURL = container.querySelector(".manifest-url");
   ok(manifestURL.href.startsWith("moz-extension://"), "href for manifestURL exists");
 
-  await uninstallAddon({document, id: addonId, name: addonName});
+  yield uninstallAddon({document, id: addonId, name: addonName});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function testTemporaryWebExtension() {
+add_task(function* testTemporaryWebExtension() {
   let addonName = "test-devtools-webextension-noid";
-  let { tab, document } = await openAboutDebugging("addons");
+  let { tab, document } = yield openAboutDebugging("addons");
 
-  await waitForInitialAddonList(document);
-  await installAddon({
+  yield waitForInitialAddonList(document);
+  yield installAddon({
     document,
     path: "addons/test-devtools-webextension-noid/manifest.json",
     name: addonName,
@@ -83,18 +83,18 @@ add_task(async function testTemporaryWebExtension() {
   let temporaryID = container.querySelector(".temporary-id-url");
   ok(temporaryID, "Temporary ID message does appear");
 
-  await uninstallAddon({document, id: addonId, name: addonName});
+  yield uninstallAddon({document, id: addonId, name: addonName});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function testUnknownManifestProperty() {
+add_task(function* testUnknownManifestProperty() {
   let addonId = "test-devtools-webextension-unknown-prop@mozilla.org";
   let addonName = "test-devtools-webextension-unknown-prop";
-  let { tab, document } = await openAboutDebugging("addons");
+  let { tab, document } = yield openAboutDebugging("addons");
 
-  await waitForInitialAddonList(document);
-  await installAddon({
+  yield waitForInitialAddonList(document);
+  yield installAddon({
     document,
     path: "addons/test-devtools-webextension-unknown-prop/manifest.json",
     name: addonName,
@@ -102,10 +102,10 @@ add_task(async function testUnknownManifestProperty() {
   });
 
   info("Wait until the addon appears in about:debugging");
-  let container = await waitUntilAddonContainer(addonName, document);
+  let container = yield waitUntilAddonContainer(addonName, document);
 
   info("Wait until the installation message appears for the new addon");
-  await waitUntilElement(".addon-target-messages", container);
+  yield waitUntilElement(".addon-target-messages", container);
 
   let messages = container.querySelectorAll(".addon-target-message");
   ok(messages.length === 1, "there is one message");
@@ -114,7 +114,7 @@ add_task(async function testUnknownManifestProperty() {
   ok(messages[0].classList.contains("addon-target-warning-message"),
      "the message is a warning");
 
-  await uninstallAddon({document, id: addonId, name: addonName});
+  yield uninstallAddon({document, id: addonId, name: addonName});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension.js b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension.js
index 43bbf9d2d6ae..7d412ef01cf6 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension.js
@@ -24,10 +24,10 @@ const {
  * - when the debug button is clicked on a webextension, the opened toolbox
  *   has a working webconsole with the background page as default target;
  */
-add_task(async function testWebExtensionsToolboxWebConsole() {
+add_task(function* testWebExtensionsToolboxWebConsole() {
   let {
     tab, document, debugBtn,
-  } = await setupTestAboutDebuggingWebExtension(ADDON_NAME, ADDON_MANIFEST_PATH);
+  } = yield setupTestAboutDebuggingWebExtension(ADDON_NAME, ADDON_MANIFEST_PATH);
 
   // Be careful, this JS function is going to be executed in the addon toolbox,
   // which lives in another process. So do not try to use any scope variable!
@@ -73,9 +73,9 @@ add_task(async function testWebExtensionsToolboxWebConsole() {
 
   debugBtn.click();
 
-  await onToolboxClose;
+  yield onToolboxClose;
   ok(true, "Addon toolbox closed");
 
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
-  await closeAboutDebugging(tab);
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_inspector.js b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_inspector.js
index b5ae77d425a9..b1b07a8310fa 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_inspector.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_inspector.js
@@ -23,10 +23,10 @@ const {
  * - the webextension developer toolbox has a working Inspector panel, with the
  *   background page as default target;
  */
-add_task(async function testWebExtensionsToolboxInspector() {
+add_task(function* testWebExtensionsToolboxInspector() {
   let {
     tab, document, debugBtn,
-  } = await setupTestAboutDebuggingWebExtension(ADDON_NAME, ADDON_PATH);
+  } = yield setupTestAboutDebuggingWebExtension(ADDON_NAME, ADDON_PATH);
 
   // Be careful, this JS function is going to be executed in the addon toolbox,
   // which lives in another process. So do not try to use any scope variable!
@@ -78,10 +78,10 @@ add_task(async function testWebExtensionsToolboxInspector() {
 
   let onToolboxClose = BrowserToolboxProcess.once("close");
   debugBtn.click();
-  await onToolboxClose;
+  yield onToolboxClose;
 
   ok(true, "Addon toolbox closed");
 
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
-  await closeAboutDebugging(tab);
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_nobg.js b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_nobg.js
index 5564d4f551be..50b4fceb99a9 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_nobg.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_nobg.js
@@ -25,10 +25,10 @@ const {
  *   the expected message, which warns the user that the current page is not a real
  *   webextension context);
  */
-add_task(async function testWebExtensionsToolboxNoBackgroundPage() {
+add_task(function* testWebExtensionsToolboxNoBackgroundPage() {
   let {
     tab, document, debugBtn,
-  } = await setupTestAboutDebuggingWebExtension(ADDON_NOBG_NAME, ADDON_NOBG_PATH);
+  } = yield setupTestAboutDebuggingWebExtension(ADDON_NOBG_NAME, ADDON_NOBG_PATH);
 
   // Be careful, this JS function is going to be executed in the addon toolbox,
   // which lives in another process. So do not try to use any scope variable!
@@ -80,10 +80,10 @@ add_task(async function testWebExtensionsToolboxNoBackgroundPage() {
 
   let onToolboxClose = BrowserToolboxProcess.once("close");
   debugBtn.click();
-  await onToolboxClose;
+  yield onToolboxClose;
 
   ok(true, "Addon toolbox closed");
 
-  await uninstallAddon({document, id: ADDON_NOBG_ID, name: ADDON_NOBG_NAME});
-  await closeAboutDebugging(tab);
+  yield uninstallAddon({document, id: ADDON_NOBG_ID, name: ADDON_NOBG_NAME});
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js
index 673a0202f921..38dc1f4150c1 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debug_webextension_popup.js
@@ -41,7 +41,7 @@ function makeWidgetId(id) {
   return id.replace(/[^a-z0-9_-]/g, "_");
 }
 
-add_task(async function testWebExtensionsToolboxSwitchToPopup() {
+add_task(function* testWebExtensionsToolboxSwitchToPopup() {
   let onReadyForOpenPopup;
   let onPopupCustomMessage;
 
@@ -78,7 +78,7 @@ add_task(async function testWebExtensionsToolboxSwitchToPopup() {
 
   let {
     tab, document, debugBtn,
-  } = await setupTestAboutDebuggingWebExtension(ADDON_NAME, ADDON_MANIFEST_PATH);
+  } = yield setupTestAboutDebuggingWebExtension(ADDON_NAME, ADDON_MANIFEST_PATH);
 
   // Be careful, this JS function is going to be executed in the addon toolbox,
   // which lives in another process. So do not try to use any scope variable!
@@ -165,7 +165,7 @@ add_task(async function testWebExtensionsToolboxSwitchToPopup() {
 
   debugBtn.click();
 
-  await onReadyForOpenPopup;
+  yield onReadyForOpenPopup;
 
   let browserActionId = makeWidgetId(ADDON_ID) + "-browser-action";
   let browserActionEl = window.document.getElementById(browserActionId);
@@ -174,16 +174,16 @@ add_task(async function testWebExtensionsToolboxSwitchToPopup() {
   browserActionEl.click();
   info("Clicked on the browserAction button");
 
-  let args = await onPopupCustomMessage;
+  let args = yield onPopupCustomMessage;
   ok(true, "Received console message from the popup page function as expected");
   is(args[0], "popupPageFunctionCalled", "Got the expected console message");
   is(args[1] && args[1].name, ADDON_NAME,
      "Got the expected manifest from WebExtension API");
 
-  await onToolboxClose;
+  yield onToolboxClose;
 
   ok(true, "Addon toolbox closed");
 
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
-  await closeAboutDebugging(tab);
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_debugging_initial_state.js b/devtools/client/aboutdebugging/test/browser_addons_debugging_initial_state.js
index c39659fe3cd3..8a63d00612c6 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_debugging_initial_state.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_debugging_initial_state.js
@@ -30,15 +30,15 @@ const TEST_DATA = [
   }
 ];
 
-add_task(async function () {
+add_task(function* () {
   for (let testData of TEST_DATA) {
-    await testCheckboxState(testData);
+    yield testCheckboxState(testData);
   }
 });
 
-async function testCheckboxState(testData) {
+function* testCheckboxState(testData) {
   info("Set preferences as defined by the current test data.");
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     let options = {"set": [
       ["devtools.chrome.enabled", testData.chromeEnabled],
       ["devtools.debugger.remote-enabled", testData.debuggerRemoteEnable],
@@ -46,11 +46,11 @@ async function testCheckboxState(testData) {
     SpecialPowers.pushPrefEnv(options, resolve);
   });
 
-  let { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+  let { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   info("Install a test addon.");
-  await installAddon({
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: ADDON_NAME,
@@ -67,7 +67,7 @@ async function testCheckboxState(testData) {
     "Debug buttons should be in the expected state");
 
   info("Uninstall test addon installed earlier.");
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 }
diff --git a/devtools/client/aboutdebugging/test/browser_addons_install.js b/devtools/client/aboutdebugging/test/browser_addons_install.js
index 9e26e43db8fe..5ab740dd42f0 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_install.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_install.js
@@ -34,26 +34,26 @@ function promiseWriteWebManifestForExtension(manifest, dir) {
     dir.path, manifest.applications.gecko.id, files, true);
 }
 
-add_task(async function testLegacyInstallSuccess() {
-  let { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+add_task(function* testLegacyInstallSuccess() {
+  let { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   // Install this add-on, and verify that it appears in the about:debugging UI
-  await installAddon({
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: ADDON_NAME,
   });
 
   // Install the add-on, and verify that it disappears in the about:debugging UI
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function testWebextensionInstallError() {
-  let { tab, document, window } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+add_task(function* testWebextensionInstallError() {
+  let { tab, document, window } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   // Trigger the file picker by clicking on the button
   mockFilePicker(window, getSupportsFile("addons/bad/manifest.json").file);
@@ -61,14 +61,14 @@ add_task(async function testWebextensionInstallError() {
 
   info("wait for the install error to appear");
   let top = document.querySelector(".addons-top");
-  await waitUntilElement(".addons-install-error", top);
+  yield waitUntilElement(".addons-install-error", top);
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function testWebextensionInstallErrorRetry() {
-  let { tab, document, window } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+add_task(function* testWebextensionInstallErrorRetry() {
+  let { tab, document, window } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   let tempdir = AddonTestUtils.tempDir.clone();
   let addonId = "invalid-addon-install-retry@mozilla.org";
@@ -85,7 +85,7 @@ add_task(async function testWebextensionInstallErrorRetry() {
     content_scripts: { matches: "http://*/", js: "foo.js" },
   };
 
-  await promiseWriteWebManifestForExtension(manifest, tempdir);
+  yield promiseWriteWebManifestForExtension(manifest, tempdir);
 
   // Mock the file picker to select a test addon.
   let manifestFile = tempdir.clone();
@@ -97,7 +97,7 @@ add_task(async function testWebextensionInstallErrorRetry() {
 
   info("wait for the install error to appear");
   let top = document.querySelector(".addons-top");
-  await waitUntilElement(".addons-install-error", top);
+  yield waitUntilElement(".addons-install-error", top);
 
   let retryButton = document.querySelector("button.addons-install-retry");
   is(retryButton.textContent, "Retry", "Retry button has a good label");
@@ -108,7 +108,7 @@ add_task(async function testWebextensionInstallErrorRetry() {
     matches: ["http://*/"],
     js: ["foo.js"],
   }];
-  await promiseWriteWebManifestForExtension(manifest, tempdir);
+  yield promiseWriteWebManifestForExtension(manifest, tempdir);
 
   let addonEl = document.querySelector(`[data-addon-id="${addonId}"]`);
   // Verify this add-on isn't installed yet.
@@ -118,11 +118,11 @@ add_task(async function testWebextensionInstallErrorRetry() {
   retryButton.click();
 
   info("Wait for the add-on to be shown");
-  await waitUntilElement(`[data-addon-id="${addonId}"]`, document);
+  yield waitUntilElement(`[data-addon-id="${addonId}"]`, document);
   info("Addon is installed");
 
   // Install the add-on, and verify that it disappears in the about:debugging UI
-  await uninstallAddon({document, id: addonId, name: addonName});
+  yield uninstallAddon({document, id: addonId, name: addonName});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_reload.js b/devtools/client/aboutdebugging/test/browser_addons_reload.js
index a2de070c41c0..dab21f6df787 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_reload.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_reload.js
@@ -60,11 +60,11 @@ class TempWebExt {
   }
 }
 
-add_task(async function reloadButtonReloadsAddon() {
-  const { tab, document, window } = await openAboutDebugging("addons");
+add_task(function* reloadButtonReloadsAddon() {
+  const { tab, document, window } = yield openAboutDebugging("addons");
   const { AboutDebugging } = window;
-  await waitForInitialAddonList(document);
-  await installAddon({
+  yield waitForInitialAddonList(document);
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: ADDON_NAME,
@@ -84,21 +84,21 @@ add_task(async function reloadButtonReloadsAddon() {
 
   let reloaded = once(AboutDebugging, "addon-reload");
   reloadButton.click();
-  await reloaded;
+  yield reloaded;
 
-  const [reloadedAddon] = await onInstalled;
+  const [reloadedAddon] = yield onInstalled;
   is(reloadedAddon.name, ADDON_NAME,
      "Add-on was reloaded: " + reloadedAddon.name);
 
-  await onBootstrapInstallCalled;
-  await tearDownAddon(reloadedAddon);
-  await closeAboutDebugging(tab);
+  yield onBootstrapInstallCalled;
+  yield tearDownAddon(reloadedAddon);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function reloadButtonRefreshesMetadata() {
-  const { tab, document, window } = await openAboutDebugging("addons");
+add_task(function* reloadButtonRefreshesMetadata() {
+  const { tab, document, window } = yield openAboutDebugging("addons");
   const { AboutDebugging } = window;
-  await waitForInitialAddonList(document);
+  yield waitForInitialAddonList(document);
 
   const manifestBase = {
     "manifest_version": 2,
@@ -115,13 +115,13 @@ add_task(async function reloadButtonRefreshesMetadata() {
   tempExt.writeManifest(manifestBase);
 
   const onInstalled = promiseAddonEvent("onInstalled");
-  await AddonManager.installTemporaryAddon(tempExt.sourceDir);
+  yield AddonManager.installTemporaryAddon(tempExt.sourceDir);
 
   info("Wait until addon onInstalled event is received");
-  await onInstalled;
+  yield onInstalled;
 
   info("Wait until addon appears in about:debugging#addons");
-  await waitUntilAddonContainer("Temporary web extension", document);
+  yield waitUntilAddonContainer("Temporary web extension", document);
 
   const newName = "Temporary web extension (updated)";
   tempExt.writeManifest(Object.assign({}, manifestBase, {name: newName}));
@@ -131,34 +131,34 @@ add_task(async function reloadButtonRefreshesMetadata() {
   const reloadButton = getReloadButton(document, manifestBase.name);
   let reloaded = once(AboutDebugging, "addon-reload");
   reloadButton.click();
-  await reloaded;
+  yield reloaded;
 
   info("Wait until addon onInstalled event is received again");
-  const [reloadedAddon] = await onReInstall;
+  const [reloadedAddon] = yield onReInstall;
 
   info("Wait until addon name is updated in about:debugging#addons");
-  await waitUntilAddonContainer(newName, document);
+  yield waitUntilAddonContainer(newName, document);
 
-  await tearDownAddon(reloadedAddon);
+  yield tearDownAddon(reloadedAddon);
   tempExt.remove();
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function onlyTempInstalledAddonsCanBeReloaded() {
-  const { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
-  await installAddonWithManager(getSupportsFile("addons/bug1273184.xpi").file);
+add_task(function* onlyTempInstalledAddonsCanBeReloaded() {
+  const { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
+  yield installAddonWithManager(getSupportsFile("addons/bug1273184.xpi").file);
 
   info("Wait until addon appears in about:debugging#addons");
-  await waitUntilAddonContainer(PACKAGED_ADDON_NAME, document);
+  yield waitUntilAddonContainer(PACKAGED_ADDON_NAME, document);
 
   info("Retrieved the installed addon from the addon manager");
-  const addon = await getAddonByID(PACKAGED_ADDON_ID);
+  const addon = yield getAddonByID(PACKAGED_ADDON_ID);
   is(addon.name, PACKAGED_ADDON_NAME, "Addon name is correct");
 
   const reloadButton = getReloadButton(document, addon.name);
   ok(!reloadButton, "There should not be a reload button");
 
-  await tearDownAddon(addon);
-  await closeAboutDebugging(tab);
+  yield tearDownAddon(addon);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_remove.js b/devtools/client/aboutdebugging/test/browser_addons_remove.js
index 5c45acccc56d..c0e096a19720 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_remove.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_remove.js
@@ -12,15 +12,15 @@ function getRemoveButton(document, id) {
   return document.querySelector(`[data-addon-id="${id}"] .uninstall-button`);
 }
 
-add_task(async function removeLegacyExtension() {
+add_task(function* removeLegacyExtension() {
   const addonID = "test-devtools@mozilla.org";
   const addonName = "test-devtools";
 
-  const { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+  const { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   // Install this add-on, and verify that it appears in the about:debugging UI
-  await installAddon({
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: addonName,
@@ -30,22 +30,22 @@ add_task(async function removeLegacyExtension() {
 
   info("Click on the remove button and wait until the addon container is removed");
   getRemoveButton(document, addonID).click();
-  await waitUntil(() => !getTargetEl(document, addonID), 100);
+  yield waitUntil(() => !getTargetEl(document, addonID), 100);
 
   info("add-on is not shown");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function removeWebextension() {
+add_task(function* removeWebextension() {
   const addonID = "test-devtools-webextension@mozilla.org";
   const addonName = "test-devtools-webextension";
 
-  const { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+  const { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   // Install this add-on, and verify that it appears in the about:debugging UI
-  await installAddon({
+  yield installAddon({
     document,
     path: "addons/test-devtools-webextension/manifest.json",
     name: addonName,
@@ -56,26 +56,26 @@ add_task(async function removeWebextension() {
 
   info("Click on the remove button and wait until the addon container is removed");
   getRemoveButton(document, addonID).click();
-  await waitUntil(() => !getTargetEl(document, addonID), 100);
+  yield waitUntil(() => !getTargetEl(document, addonID), 100);
 
   info("add-on is not shown");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function onlyTempInstalledAddonsCanBeRemoved() {
-  const { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+add_task(function* onlyTempInstalledAddonsCanBeRemoved() {
+  const { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
-  await installAddonWithManager(getSupportsFile("addons/bug1273184.xpi").file);
-  const addon = await getAddonByID("bug1273184@tests");
+  yield installAddonWithManager(getSupportsFile("addons/bug1273184.xpi").file);
+  const addon = yield getAddonByID("bug1273184@tests");
 
   info("Wait until addon appears in about:debugging#addons");
-  await waitUntilAddonContainer(PACKAGED_ADDON_NAME, document);
+  yield waitUntilAddonContainer(PACKAGED_ADDON_NAME, document);
 
   const removeButton = getRemoveButton(document, addon.id);
   ok(!removeButton, "remove button is not shown");
 
-  await tearDownAddon(addon);
-  await closeAboutDebugging(tab);
+  yield tearDownAddon(addon);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_addons_toggle_debug.js b/devtools/client/aboutdebugging/test/browser_addons_toggle_debug.js
index cdba839d5b27..946adb354d64 100644
--- a/devtools/client/aboutdebugging/test/browser_addons_toggle_debug.js
+++ b/devtools/client/aboutdebugging/test/browser_addons_toggle_debug.js
@@ -9,9 +9,9 @@
 const ADDON_ID = "test-devtools@mozilla.org";
 const ADDON_NAME = "test-devtools";
 
-add_task(async function () {
+add_task(function* () {
   info("Turn off addon debugging.");
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     let options = {"set": [
       ["devtools.chrome.enabled", false],
       ["devtools.debugger.remote-enabled", false],
@@ -19,11 +19,11 @@ add_task(async function () {
     SpecialPowers.pushPrefEnv(options, resolve);
   });
 
-  let { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+  let { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
   info("Install a test addon.");
-  await installAddon({
+  yield installAddon({
     document,
     path: "addons/unpacked/install.rdf",
     name: ADDON_NAME,
@@ -51,9 +51,9 @@ add_task(async function () {
   info("All debug buttons are disabled again.");
 
   info("Uninstall addon installed earlier.");
-  await uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
+  yield uninstallAddon({document, id: ADDON_ID, name: ADDON_NAME});
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
 function getDebugButtons(document) {
diff --git a/devtools/client/aboutdebugging/test/browser_page_not_found.js b/devtools/client/aboutdebugging/test/browser_page_not_found.js
index e4307079521d..2a126c53d91a 100644
--- a/devtools/client/aboutdebugging/test/browser_page_not_found.js
+++ b/devtools/client/aboutdebugging/test/browser_page_not_found.js
@@ -6,36 +6,36 @@
 // error page.
 // Every url navigating including #invalid-hash should be kept in history and
 // navigate back as expected.
-add_task(async function () {
-  let { tab, document } = await openAboutDebugging("invalid-hash");
+add_task(function* () {
+  let { tab, document } = yield openAboutDebugging("invalid-hash");
   let element = document.querySelector(".header-name");
   is(element.textContent, "Page not found", "Show error page");
 
   info("Opening addons-panel panel");
   document.querySelector("[aria-controls='addons-panel']").click();
-  await waitUntilElement("#addons-panel", document);
+  yield waitUntilElement("#addons-panel", document);
 
-  await waitForInitialAddonList(document);
+  yield waitForInitialAddonList(document);
   element = document.querySelector(".header-name");
   is(element.textContent, "Add-ons", "Show Addons");
 
   info("Opening about:debugging#invalid-hash");
   window.openUILinkIn("about:debugging#invalid-hash", "current");
-  await waitUntilElement(".error-page", document);
+  yield waitUntilElement(".error-page", document);
 
   element = document.querySelector(".header-name");
   is(element.textContent, "Page not found", "Show error page");
 
   gBrowser.goBack();
-  await waitUntilElement("#addons-panel", document);
-  await waitForInitialAddonList(document);
+  yield waitUntilElement("#addons-panel", document);
+  yield waitForInitialAddonList(document);
   element = document.querySelector(".header-name");
   is(element.textContent, "Add-ons", "Show Addons");
 
   gBrowser.goBack();
-  await waitUntilElement(".error-page", document);
+  yield waitUntilElement(".error-page", document);
   element = document.querySelector(".header-name");
   is(element.textContent, "Page not found", "Show error page");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers.js b/devtools/client/aboutdebugging/test/browser_service_workers.js
index a0191d53dfed..ff084063e632 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers.js
@@ -8,16 +8,16 @@
 const SERVICE_WORKER = URL_ROOT + "service-workers/empty-sw.js";
 const TAB_URL = URL_ROOT + "service-workers/empty-sw.html";
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   let serviceWorkersElement = getServiceWorkerList(document);
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     // Check that the service worker appears in the UI
     let names = [...document.querySelectorAll("#service-workers .target-name")];
     names = names.map(element => element.textContent);
@@ -26,7 +26,7 @@ add_task(async function () {
   info("The service worker url appears in the list");
 
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
@@ -38,6 +38,6 @@ add_task(async function () {
   ok(!names.includes(SERVICE_WORKER),
     "The service worker url is no longer in the list: " + names);
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_fetch_flag.js b/devtools/client/aboutdebugging/test/browser_service_workers_fetch_flag.js
index 8df310d872be..c1bb720c4e3c 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_fetch_flag.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_fetch_flag.js
@@ -8,16 +8,16 @@
 const EMPTY_SW_TAB_URL = URL_ROOT + "service-workers/empty-sw.html";
 const FETCH_SW_TAB_URL = URL_ROOT + "service-workers/fetch-sw.html";
 
-async function testBody(url, expecting) {
-  await enableServiceWorkerDebugging();
-  let { tab, document } = await openAboutDebugging("workers");
+function* testBody(url, expecting) {
+  yield enableServiceWorkerDebugging();
+  let { tab, document } = yield openAboutDebugging("workers");
 
-  let swTab = await addTab(url);
+  let swTab = yield addTab(url);
 
   let serviceWorkersElement = getServiceWorkerList(document);
 
   info("Wait for fetch flag.");
-  await waitUntil(() => {
+  yield waitUntil(() => {
     let fetchFlags =
       [...document.querySelectorAll("#service-workers .service-worker-fetch-flag")];
     fetchFlags = fetchFlags.map(element => element.textContent);
@@ -27,7 +27,7 @@ async function testBody(url, expecting) {
   info("Found correct fetch flag.");
 
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
@@ -38,11 +38,11 @@ async function testBody(url, expecting) {
   names = names.map(element => element.textContent);
   ok(names.length == 0, "All service workers were removed from the list.");
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 }
 
-add_task(async function () {
-  await testBody(FETCH_SW_TAB_URL, "Listening for fetch events.");
-  await testBody(EMPTY_SW_TAB_URL, "Not listening for fetch events.");
+add_task(function* () {
+  yield testBody(FETCH_SW_TAB_URL, "Listening for fetch events.");
+  yield testBody(EMPTY_SW_TAB_URL, "Not listening for fetch events.");
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_multi_content_process.js b/devtools/client/aboutdebugging/test/browser_service_workers_multi_content_process.js
index 123a385cf138..0bb2421ae44e 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_multi_content_process.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_multi_content_process.js
@@ -10,12 +10,12 @@
 const SERVICE_WORKER = URL_ROOT + "service-workers/empty-sw.js";
 const TAB_URL = URL_ROOT + "service-workers/empty-sw.html";
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
   info("Force two content processes");
-  await pushPref("dom.ipc.processCount", 2);
+  yield pushPref("dom.ipc.processCount", 2);
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
   let warningSection = document.querySelector(".service-worker-multi-process");
   let img = warningSection.querySelector(".warning");
@@ -23,12 +23,12 @@ add_task(async function () {
 
   let serviceWorkersElement = getServiceWorkerList(document);
 
-  let swTab = await addTab(TAB_URL, { background: true });
+  let swTab = yield addTab(TAB_URL, { background: true });
 
   info("Wait for service worker to appear in the list");
   // Check that the service worker appears in the UI
   let serviceWorkerContainer =
-    await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+    yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
   info("Check that service worker buttons are disabled.");
   let debugButton = getDebugButton(serviceWorkerContainer);
@@ -39,8 +39,8 @@ add_task(async function () {
     let hasWarning = document.querySelector(".service-worker-multi-process");
     return !hasWarning && !debugButton.disabled;
   }, 100);
-  await pushPref("dom.ipc.processCount", 1);
-  await onWarningCleared;
+  yield pushPref("dom.ipc.processCount", 1);
+  yield onWarningCleared;
   ok(!debugButton.disabled, "Debug button is enabled.");
 
   info("Update the preference back to 2");
@@ -48,8 +48,8 @@ add_task(async function () {
     let hasWarning = document.querySelector(".service-worker-multi-process");
     return hasWarning && getDebugButton(serviceWorkerContainer).disabled;
   }, 100);
-  await pushPref("dom.ipc.processCount", 2);
-  await onWarningRestored;
+  yield pushPref("dom.ipc.processCount", 2);
+  yield onWarningRestored;
 
   // Update the reference to the debugButton, as the previous DOM element might have been
   // deleted.
@@ -58,14 +58,14 @@ add_task(async function () {
 
   info("Unregister service worker");
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
   }
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
 
 function getDebugButton(serviceWorkerContainer) {
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_not_compatible.js b/devtools/client/aboutdebugging/test/browser_service_workers_not_compatible.js
index 820228c6d445..6221230b556e 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_not_compatible.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_not_compatible.js
@@ -11,8 +11,8 @@
 
 var imgClass = ".service-worker-disabled .warning";
 
-add_task(async function () {
-  await new Promise(done => {
+add_task(function* () {
+  yield new Promise(done => {
     info("disable service workers");
     let options = {"set": [
       ["dom.serviceWorkers.enabled", false],
@@ -20,16 +20,16 @@ add_task(async function () {
     SpecialPowers.pushPrefEnv(options, done);
   });
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
   // Check that the warning img appears in the UI
   let img = document.querySelector(imgClass);
   ok(img, "warning message is rendered");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function () {
-  await new Promise(done => {
+add_task(function* () {
+  yield new Promise(done => {
     info("set private browsing mode as default");
     let options = {"set": [
       ["browser.privatebrowsing.autostart", true],
@@ -37,24 +37,24 @@ add_task(async function () {
     SpecialPowers.pushPrefEnv(options, done);
   });
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
   // Check that the warning img appears in the UI
   let img = document.querySelector(imgClass);
   ok(img, "warning message is rendered");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Opening a new private window");
   let win = OpenBrowserWindow({private: true});
-  await waitForDelayedStartupFinished(win);
+  yield waitForDelayedStartupFinished(win);
 
-  let { tab, document } = await openAboutDebugging("workers", win);
+  let { tab, document } = yield openAboutDebugging("workers", win);
   // Check that the warning img appears in the UI
   let img = document.querySelector(imgClass);
   ok(img, "warning message is rendered");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
   win.close();
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_push.js b/devtools/client/aboutdebugging/test/browser_service_workers_push.js
index d917f1363108..087e0c535263 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_push.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_push.js
@@ -14,19 +14,19 @@
 const SERVICE_WORKER = URL_ROOT + "service-workers/push-sw.js";
 const TAB_URL = URL_ROOT + "service-workers/push-sw.html";
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
-  let { tab, document } = await openAboutDebugging("workers");
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
+  let { tab, document } = yield openAboutDebugging("workers");
 
   // Listen for mutations in the service-workers list.
   let serviceWorkersElement = getServiceWorkerList(document);
 
   // Open a tab that registers a push service worker.
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   info("Make the test page notify us when the service worker sends a message.");
 
-  await ContentTask.spawn(swTab.linkedBrowser, {}, function () {
+  yield ContentTask.spawn(swTab.linkedBrowser, {}, function () {
     let win = content.wrappedJSObject;
     win.navigator.serviceWorker.addEventListener("message", function (event) {
       sendAsyncMessage(event.data);
@@ -37,14 +37,14 @@ add_task(async function () {
   let onClaimed = onTabMessage(swTab, "sw-claimed");
 
   info("Wait until the service worker appears in the UI");
-  await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+  yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
   info("Ensure that the registration resolved before trying to interact with " +
     "the service worker.");
-  await waitForServiceWorkerRegistered(swTab);
+  yield waitForServiceWorkerRegistered(swTab);
   ok(true, "Service worker registration resolved");
 
-  await waitForServiceWorkerActivation(SERVICE_WORKER, document);
+  yield waitForServiceWorkerActivation(SERVICE_WORKER, document);
 
   // Retrieve the Push button for the worker.
   let names = [...document.querySelectorAll("#service-workers .target-name")];
@@ -57,26 +57,26 @@ add_task(async function () {
   ok(pushBtn, "Found its push button");
 
   info("Wait for the service worker to claim the test window before proceeding.");
-  await onClaimed;
+  yield onClaimed;
 
   info("Click on the Push button and wait for the service worker to receive " +
     "a push notification");
   let onPushNotification = onTabMessage(swTab, "sw-pushed");
 
   pushBtn.click();
-  await onPushNotification;
+  yield onPushNotification;
   ok(true, "Service worker received a push notification");
 
   // Finally, unregister the service worker itself.
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
   }
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
 
 /**
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_push_service.js b/devtools/client/aboutdebugging/test/browser_service_workers_push_service.js
index 9939d1e7b52b..f29236130bde 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_push_service.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_push_service.js
@@ -16,11 +16,11 @@ const FAKE_ENDPOINT = "https://fake/endpoint";
 const PushService = Cc["@mozilla.org/push/Service;1"]
   .getService(Ci.nsIPushService).wrappedJSObject;
 
-add_task(async function () {
+add_task(function* () {
   info("Turn on workers via mochitest http.");
-  await enableServiceWorkerDebugging();
+  yield enableServiceWorkerDebugging();
   // Enable the push service.
-  await pushPref("dom.push.connection.enabled", true);
+  yield pushPref("dom.push.connection.enabled", true);
 
   info("Mock the push service");
   PushService.service = {
@@ -52,18 +52,18 @@ add_task(async function () {
     },
   };
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
   // Listen for mutations in the service-workers list.
   let serviceWorkersElement = document.getElementById("service-workers");
 
   // Open a tab that registers a push service worker.
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   info("Wait until the service worker appears in about:debugging");
-  await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+  yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
-  await waitForServiceWorkerActivation(SERVICE_WORKER, document);
+  yield waitForServiceWorkerActivation(SERVICE_WORKER, document);
 
   // Wait for the service worker details to update.
   let names = [...document.querySelectorAll("#service-workers .target-name")];
@@ -74,7 +74,7 @@ add_task(async function () {
 
   // Retrieve the push subscription endpoint URL, and verify it looks good.
   info("Wait for the push URL");
-  let pushURL = await waitUntilElement(".service-worker-push-url", targetContainer);
+  let pushURL = yield waitUntilElement(".service-worker-push-url", targetContainer);
 
   info("Found the push service URL in the service worker details");
   is(pushURL.textContent, FAKE_ENDPOINT, "The push service URL looks correct");
@@ -87,12 +87,12 @@ add_task(async function () {
 
   // Wait for the service worker details to update again
   info("Wait until the push URL is removed from the UI");
-  await waitUntil(() => !targetContainer.querySelector(".service-worker-push-url"), 100);
+  yield waitUntil(() => !targetContainer.querySelector(".service-worker-push-url"), 100);
   info("The push service URL should be removed");
 
   // Finally, unregister the service worker itself.
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
@@ -101,6 +101,6 @@ add_task(async function () {
   info("Unmock the push service");
   PushService.service = null;
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_start.js b/devtools/client/aboutdebugging/test/browser_service_workers_start.js
index 12f342e929ae..1dda465dff7a 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_start.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_start.js
@@ -14,29 +14,29 @@ const TAB_URL = URL_ROOT + "service-workers/empty-sw.html";
 
 const SW_TIMEOUT = 1000;
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
-  await pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
-  await pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
+  yield pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
+  yield pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
   // Listen for mutations in the service-workers list.
   let serviceWorkersElement = getServiceWorkerList(document);
 
   // Open a tab that registers an empty service worker.
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   // Wait for the service-workers list to update.
   info("Wait until the service worker appears in about:debugging");
-  await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+  yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
   info("Ensure that the registration resolved before trying to interact with " +
     "the service worker.");
-  await waitForServiceWorkerRegistered(swTab);
+  yield waitForServiceWorkerRegistered(swTab);
   ok(true, "Service worker registration resolved");
 
-  await waitForServiceWorkerActivation(SERVICE_WORKER, document);
+  yield waitForServiceWorkerActivation(SERVICE_WORKER, document);
 
   // Retrieve the Target element corresponding to the service worker.
   let names = [...document.querySelectorAll("#service-workers .target-name")];
@@ -49,7 +49,7 @@ add_task(async function () {
   // already stopped and the start button is visible. Wait until the service worker is
   // stopped.
   info("Wait until the start button is visible");
-  await waitUntilElement(".start-button", targetElement);
+  yield waitUntilElement(".start-button", targetElement);
 
   // We should now have a Start button but no Debug button.
   let startBtn = targetElement.querySelector(".start-button");
@@ -60,7 +60,7 @@ add_task(async function () {
   startBtn.click();
 
   info("Wait until the service worker starts and the debug button appears");
-  await waitUntilElement(".debug-button", targetElement);
+  yield waitUntilElement(".debug-button", targetElement);
   info("Found the debug button");
 
   // Check that we have a Debug button but not a Start button again.
@@ -68,12 +68,12 @@ add_task(async function () {
 
   // Finally, unregister the service worker itself.
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
   }
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_status.js b/devtools/client/aboutdebugging/test/browser_service_workers_status.js
index 3fe8e2aca4b8..e5912385a1ae 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_status.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_status.js
@@ -11,31 +11,31 @@ const SW_TIMEOUT = 2000;
 
 requestLongerTimeout(2);
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
-  await pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
-  await pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
+  yield pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
+  yield pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
   // Listen for mutations in the service-workers list.
   let serviceWorkersElement = getServiceWorkerList(document);
 
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   info("Wait until the service worker appears in about:debugging");
-  let container = await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+  let container = yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
   // We should ideally check that the service worker registration goes through the
   // "registering" and "running" steps, but it is difficult to workaround race conditions
   // for a test running on a wide variety of platforms. Due to intermittent failures, we
   // simply check that the registration transitions to "stopped".
   let status = container.querySelector(".target-status");
-  await waitUntil(() => status.textContent == "Stopped", 100);
+  yield waitUntil(() => status.textContent == "Stopped", 100);
   is(status.textContent, "Stopped", "Service worker is currently stopped");
 
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker unregistered");
   } catch (e) {
     ok(false, "Service worker not unregistered; " + e);
@@ -47,6 +47,6 @@ add_task(async function () {
   ok(!names.includes(SERVICE_WORKER),
     "The service worker url is no longer in the list: " + names);
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_timeout.js b/devtools/client/aboutdebugging/test/browser_service_workers_timeout.js
index d799f589d9dc..d2505f848ba9 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_timeout.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_timeout.js
@@ -11,22 +11,22 @@ const TAB_URL = URL_ROOT + "service-workers/empty-sw.html";
 
 const SW_TIMEOUT = 1000;
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
-  await pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
-  await pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
+  yield pushPref("dom.serviceWorkers.idle_timeout", SW_TIMEOUT);
+  yield pushPref("dom.serviceWorkers.idle_extended_timeout", SW_TIMEOUT);
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
   let serviceWorkersElement = getServiceWorkerList(document);
 
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   info("Wait until the service worker appears in about:debugging");
-  await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+  yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
   // Ensure that the registration resolved before trying to connect to the sw
-  await waitForServiceWorkerRegistered(swTab);
+  yield waitForServiceWorkerRegistered(swTab);
   ok(true, "Service worker registration resolved");
 
   // Retrieve the DEBUG button for the worker
@@ -45,12 +45,12 @@ add_task(async function () {
   });
   debugBtn.click();
 
-  let toolbox = await onToolboxReady;
+  let toolbox = yield onToolboxReady;
 
   // Wait for more than the regular timeout,
   // so that if the worker freezing doesn't work,
   // it will be destroyed and removed from the list
-  await new Promise(done => {
+  yield new Promise(done => {
     setTimeout(done, SW_TIMEOUT * 2);
   });
 
@@ -58,20 +58,20 @@ add_task(async function () {
   ok(targetElement.querySelector(".debug-button"),
     "The debug button is still there");
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   toolbox = null;
 
   // Now ensure that the worker is correctly destroyed
   // after we destroy the toolbox.
   // The DEBUG button should disappear once the worker is destroyed.
   info("Wait until the debug button disappears");
-  await waitUntil(() => {
+  yield waitUntil(() => {
     return !targetElement.querySelector(".debug-button");
   });
 
   // Finally, unregister the service worker itself.
   try {
-    await unregisterServiceWorker(swTab, serviceWorkersElement);
+    yield unregisterServiceWorker(swTab, serviceWorkersElement);
     ok(true, "Service worker registration unregistered");
   } catch (e) {
     ok(false, "SW not unregistered; " + e);
@@ -79,6 +79,6 @@ add_task(async function () {
 
   assertHasTarget(false, document, "service-workers", SERVICE_WORKER);
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_service_workers_unregister.js b/devtools/client/aboutdebugging/test/browser_service_workers_unregister.js
index 86d610aec4b1..276325c8ac5e 100644
--- a/devtools/client/aboutdebugging/test/browser_service_workers_unregister.js
+++ b/devtools/client/aboutdebugging/test/browser_service_workers_unregister.js
@@ -14,22 +14,22 @@ const SCOPE = URL_ROOT + "service-workers/";
 const SERVICE_WORKER = SCOPE + "empty-sw.js";
 const TAB_URL = SCOPE + "empty-sw.html";
 
-add_task(async function () {
-  await enableServiceWorkerDebugging();
+add_task(function* () {
+  yield enableServiceWorkerDebugging();
 
-  let { tab, document } = await openAboutDebugging("workers");
+  let { tab, document } = yield openAboutDebugging("workers");
 
   // Open a tab that registers an empty service worker.
-  let swTab = await addTab(TAB_URL);
+  let swTab = yield addTab(TAB_URL);
 
   info("Wait until the service worker appears in about:debugging");
-  await waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
+  yield waitUntilServiceWorkerContainer(SERVICE_WORKER, document);
 
-  await waitForServiceWorkerActivation(SERVICE_WORKER, document);
+  yield waitForServiceWorkerActivation(SERVICE_WORKER, document);
 
   info("Ensure that the registration resolved before trying to interact with " +
     "the service worker.");
-  await waitForServiceWorkerRegistered(swTab);
+  yield waitForServiceWorkerRegistered(swTab);
   ok(true, "Service worker registration resolved");
 
   let targets = document.querySelectorAll("#service-workers .target");
@@ -51,10 +51,10 @@ add_task(async function () {
   unregisterLink.click();
 
   info("Wait until the service worker disappears");
-  await waitUntil(() => {
+  yield waitUntil(() => {
     return !document.querySelector("#service-workers .target");
   });
 
-  await removeTab(swTab);
-  await closeAboutDebugging(tab);
+  yield removeTab(swTab);
+  yield closeAboutDebugging(tab);
 });
diff --git a/devtools/client/aboutdebugging/test/browser_tabs.js b/devtools/client/aboutdebugging/test/browser_tabs.js
index 8d9c2f0eb91f..5af4c20fe94c 100644
--- a/devtools/client/aboutdebugging/test/browser_tabs.js
+++ b/devtools/client/aboutdebugging/test/browser_tabs.js
@@ -5,12 +5,12 @@
 
 const TAB_URL = "data:text/html,<title>foo</title>";
 
-add_task(async function () {
-  let { tab, document } = await openAboutDebugging("tabs");
+add_task(function* () {
+  let { tab, document } = yield openAboutDebugging("tabs");
 
   // Wait for initial tabs list which may be empty
   let tabsElement = getTabList(document);
-  await waitUntilElement(".target-name", tabsElement);
+  yield waitUntilElement(".target-name", tabsElement);
 
   // Refresh tabsElement to get the .target-list element
   tabsElement = getTabList(document);
@@ -19,13 +19,13 @@ add_task(async function () {
   let initialTabCount = names.length;
 
   info("Open a new background tab");
-  let newTab = await addTab(TAB_URL, { background: true });
+  let newTab = yield addTab(TAB_URL, { background: true });
 
   info("Wait for the tab to appear in the list with the correct name");
-  let container = await waitUntilTabContainer("foo", document);
+  let container = yield waitUntilTabContainer("foo", document);
 
   info("Wait until the title to update");
-  await waitUntil(() => {
+  yield waitUntil(() => {
     return container.querySelector(".target-name").title === TAB_URL;
   }, 100);
 
@@ -33,7 +33,7 @@ add_task(async function () {
   ok(icon && icon.src, "Tab icon found and src attribute is not empty");
 
   info("Check if the tab icon is a valid image");
-  await new Promise(r => {
+  yield new Promise(r => {
     let image = new Image();
     image.onload = () => {
       ok(true, "Favicon is not a broken image");
@@ -47,16 +47,16 @@ add_task(async function () {
   });
 
   // Finally, close the tab
-  await removeTab(newTab);
+  yield removeTab(newTab);
 
   info("Wait until the tab container is removed");
-  await waitUntil(() => !getTabContainer("foo", document), 100);
+  yield waitUntil(() => !getTabContainer("foo", document), 100);
 
   // Check that the tab disappeared from the UI
   names = [...tabsElement.querySelectorAll("#tabs .target-name")];
   is(names.length, initialTabCount, "The tab disappeared from the UI");
 
-  await closeAboutDebugging(tab);
+  yield closeAboutDebugging(tab);
 });
 
 function getTabContainer(name, document) {
@@ -69,8 +69,8 @@ function getTabContainer(name, document) {
   return null;
 }
 
-async function waitUntilTabContainer(name, document) {
-  await waitUntil(() => {
+function* waitUntilTabContainer(name, document) {
+  yield waitUntil(() => {
     return getTabContainer(name, document);
   });
   return getTabContainer(name, document);
diff --git a/devtools/client/aboutdebugging/test/head.js b/devtools/client/aboutdebugging/test/head.js
index 0e81405a10b5..1f3873f46ff9 100644
--- a/devtools/client/aboutdebugging/test/head.js
+++ b/devtools/client/aboutdebugging/test/head.js
@@ -20,20 +20,20 @@ registerCleanupFunction(() => {
   flags.testing = false;
 });
 
-async function openAboutDebugging(page, win) {
+function* openAboutDebugging(page, win) {
   info("opening about:debugging");
   let url = "about:debugging";
   if (page) {
     url += "#" + page;
   }
 
-  let tab = await addTab(url, { window: win });
+  let tab = yield addTab(url, { window: win });
   let browser = tab.linkedBrowser;
   let document = browser.contentDocument;
   let window = browser.contentWindow;
 
   info("Wait until the main about debugging container is available");
-  await waitUntilElement(".app", document);
+  yield waitUntilElement(".app", document);
 
   return { tab, document, window };
 }
@@ -135,8 +135,8 @@ function getServiceWorkerContainer(name, document) {
  *         #service-workers section container document
  * @return {Promise} promise that resolves the service worker container element.
  */
-async function waitUntilServiceWorkerContainer(name, document) {
-  await waitUntil(() => {
+function* waitUntilServiceWorkerContainer(name, document) {
+  yield waitUntil(() => {
     return getServiceWorkerContainer(name, document);
   }, 100);
   return getServiceWorkerContainer(name, document);
@@ -152,8 +152,8 @@ async function waitUntilServiceWorkerContainer(name, document) {
  *        Parent that should contain the element.
  * @return {Promise} promise that resolves the matched DOMNode.
  */
-async function waitUntilElement(selector, parent) {
-  await waitUntil(() => {
+function* waitUntilElement(selector, parent) {
+  yield waitUntil(() => {
     return parent.querySelector(selector);
   }, 100);
   return parent.querySelector(selector);
@@ -170,7 +170,7 @@ function getTabList(document) {
     document.querySelector("#tabs.targets");
 }
 
-async function installAddon({document, path, name, isWebExtension}) {
+function* installAddon({document, path, name, isWebExtension}) {
   // Mock the file picker to select a test addon
   let MockFilePicker = SpecialPowers.MockFilePicker;
   MockFilePicker.init(window);
@@ -203,16 +203,16 @@ async function installAddon({document, path, name, isWebExtension}) {
   // Trigger the file picker by clicking on the button
   document.getElementById("load-addon-from-file").click();
 
-  await onAddonInstalled;
+  yield onAddonInstalled;
   ok(true, "Addon installed and running its bootstrap.js file");
 
   info("Wait for the addon to appear in the UI");
-  await waitUntilAddonContainer(name, document);
+  yield waitUntilAddonContainer(name, document);
 }
 
-async function uninstallAddon({document, id, name}) {
+function* uninstallAddon({document, id, name}) {
   // Now uninstall this addon
-  await new Promise(done => {
+  yield new Promise(done => {
     AddonManager.getAddonByID(id, addon => {
       let listener = {
         onUninstalled: function (uninstalledAddon) {
@@ -230,7 +230,7 @@ async function uninstallAddon({document, id, name}) {
   });
 
   info("Wait until the addon is removed from about:debugging");
-  await waitUntil(() => !getAddonContainer(name, document), 100);
+  yield waitUntil(() => !getAddonContainer(name, document), 100);
 }
 
 function getAddonCount(document) {
@@ -260,8 +260,8 @@ function getAddonContainer(name, document) {
   return null;
 }
 
-async function waitUntilAddonContainer(name, document) {
-  await waitUntil(() => {
+function* waitUntilAddonContainer(name, document) {
+  yield waitUntil(() => {
     return getAddonContainer(name, document);
   });
   return getAddonContainer(name, document);
@@ -289,10 +289,10 @@ function assertHasTarget(expected, document, type, name) {
  * @return {Promise} Resolves when the service worker is registered.
  */
 function waitForServiceWorkerRegistered(tab) {
-  return ContentTask.spawn(tab.linkedBrowser, {}, async function () {
+  return ContentTask.spawn(tab.linkedBrowser, {}, function* () {
     // Retrieve the `sw` promise created in the html page.
     let { sw } = content.wrappedJSObject;
-    await sw;
+    yield sw;
   });
 }
 
@@ -305,7 +305,7 @@ function waitForServiceWorkerRegistered(tab) {
  * @param {Node} serviceWorkersElement
  * @return {Promise} Resolves when the service worker is unregistered.
  */
-async function unregisterServiceWorker(tab, serviceWorkersElement) {
+function* unregisterServiceWorker(tab, serviceWorkersElement) {
   // Get the initial count of service worker registrations.
   let registrations = serviceWorkersElement.querySelectorAll(".target-container");
   let registrationCount = registrations.length;
@@ -317,11 +317,11 @@ async function unregisterServiceWorker(tab, serviceWorkersElement) {
   }, 100);
 
   // Unregister the service worker from the content page
-  await ContentTask.spawn(tab.linkedBrowser, {}, async function () {
+  yield ContentTask.spawn(tab.linkedBrowser, {}, function* () {
     // Retrieve the `sw` promise created in the html page
     let { sw } = content.wrappedJSObject;
-    let registration = await sw;
-    await registration.unregister();
+    let registration = yield sw;
+    yield registration.unregister();
   });
 
   return isRemoved;
@@ -347,8 +347,8 @@ function waitForDelayedStartupFinished(win) {
 /**
  * open the about:debugging page and install an addon
  */
-async function setupTestAboutDebuggingWebExtension(name, path) {
-  await new Promise(resolve => {
+function* setupTestAboutDebuggingWebExtension(name, path) {
+  yield new Promise(resolve => {
     let options = {"set": [
       // Force enabling of addons debugging
       ["devtools.chrome.enabled", true],
@@ -361,10 +361,10 @@ async function setupTestAboutDebuggingWebExtension(name, path) {
     SpecialPowers.pushPrefEnv(options, resolve);
   });
 
-  let { tab, document } = await openAboutDebugging("addons");
-  await waitForInitialAddonList(document);
+  let { tab, document } = yield openAboutDebugging("addons");
+  yield waitForInitialAddonList(document);
 
-  await installAddon({
+  yield installAddon({
     document,
     path,
     name,
@@ -386,14 +386,14 @@ async function setupTestAboutDebuggingWebExtension(name, path) {
  * Wait for aboutdebugging to be notified about the activation of the service worker
  * corresponding to the provided service worker url.
  */
-async function waitForServiceWorkerActivation(swUrl, document) {
+function* waitForServiceWorkerActivation(swUrl, document) {
   let serviceWorkersElement = getServiceWorkerList(document);
   let names = serviceWorkersElement.querySelectorAll(".target-name");
   let name = [...names].filter(element => element.textContent === swUrl)[0];
 
   let targetElement = name.parentNode.parentNode;
   let targetStatus = targetElement.querySelector(".target-status");
-  await waitUntil(() => {
+  yield waitUntil(() => {
     return targetStatus.textContent !== "Registering";
   }, 100);
 }
@@ -401,7 +401,7 @@ async function waitForServiceWorkerActivation(swUrl, document) {
 /**
  * Set all preferences needed to enable service worker debugging and testing.
  */
-async function enableServiceWorkerDebugging() {
+function* enableServiceWorkerDebugging() {
   let options = { "set": [
     // Enable service workers.
     ["dom.serviceWorkers.enabled", true],
@@ -412,7 +412,7 @@ async function enableServiceWorkerDebugging() {
   ]};
 
   // Wait for dom.ipc.processCount to be updated before releasing processes.
-  await new Promise(done => {
+  yield new Promise(done => {
     SpecialPowers.pushPrefEnv(options, done);
   });
 
@@ -466,10 +466,10 @@ function getAddonByID(addonId) {
 /**
  * Uninstall an add-on.
  */
-async function tearDownAddon(addon) {
+function* tearDownAddon(addon) {
   const onUninstalled = promiseAddonEvent("onUninstalled");
   addon.uninstall();
-  const [uninstalledAddon] = await onUninstalled;
+  const [uninstalledAddon] = yield onUninstalled;
   is(uninstalledAddon.id, addon.id,
      `Add-on was uninstalled: ${uninstalledAddon.id}`);
 }
diff --git a/devtools/client/canvasdebugger/canvasdebugger.js b/devtools/client/canvasdebugger/canvasdebugger.js
index 05072aa35c39..5feb5bc050e0 100644
--- a/devtools/client/canvasdebugger/canvasdebugger.js
+++ b/devtools/client/canvasdebugger/canvasdebugger.js
@@ -25,6 +25,7 @@ const Promise = require("Promise");
 
 const CANVAS_ACTOR_RECORDING_ATTEMPT = flags.testing ? 500 : 5000;
 
+const { Task } = require("devtools/shared/task");
 
 ChromeUtils.defineModuleGetter(this, "FileUtils",
   "resource://gre/modules/FileUtils.jsm");
diff --git a/devtools/client/canvasdebugger/snapshotslist.js b/devtools/client/canvasdebugger/snapshotslist.js
index 70533495793a..557c3611ed84 100644
--- a/devtools/client/canvasdebugger/snapshotslist.js
+++ b/devtools/client/canvasdebugger/snapshotslist.js
@@ -179,33 +179,33 @@ var SnapshotsListView = extend(WidgetMethods, {
     $("#screenshot-container").hidden = true;
     $("#snapshot-filmstrip").hidden = true;
 
-    (async function () {
+    Task.spawn(function* () {
       // Wait for a few milliseconds between presenting the function calls,
       // screenshot and thumbnails, to allow each component being
       // sequentially drawn. This gives the illusion of snappiness.
 
-      await DevToolsUtils.waitForTime(SNAPSHOT_DATA_DISPLAY_DELAY);
+      yield DevToolsUtils.waitForTime(SNAPSHOT_DATA_DISPLAY_DELAY);
       CallsListView.showCalls(calls);
       $("#debugging-pane-contents").hidden = false;
       $("#waiting-notice").hidden = true;
 
-      await DevToolsUtils.waitForTime(SNAPSHOT_DATA_DISPLAY_DELAY);
+      yield DevToolsUtils.waitForTime(SNAPSHOT_DATA_DISPLAY_DELAY);
       CallsListView.showThumbnails(thumbnails);
       $("#snapshot-filmstrip").hidden = false;
 
-      await DevToolsUtils.waitForTime(SNAPSHOT_DATA_DISPLAY_DELAY);
+      yield DevToolsUtils.waitForTime(SNAPSHOT_DATA_DISPLAY_DELAY);
       CallsListView.showScreenshot(screenshot);
       $("#screenshot-container").hidden = false;
 
       window.emit(EVENTS.SNAPSHOT_RECORDING_SELECTED);
-    })();
+    });
   },
 
   /**
    * The click listener for the "clear" button in this container.
    */
   _onClearButtonClick: function () {
-    (async function () {
+    Task.spawn(function* () {
       SnapshotsListView.empty();
       CallsListView.empty();
 
@@ -213,7 +213,7 @@ var SnapshotsListView = extend(WidgetMethods, {
       $("#empty-notice").hidden = true;
       $("#waiting-notice").hidden = true;
 
-      if (await gFront.isInitialized()) {
+      if (yield gFront.isInitialized()) {
         $("#empty-notice").hidden = false;
       } else {
         $("#reload-notice").hidden = false;
@@ -224,7 +224,7 @@ var SnapshotsListView = extend(WidgetMethods, {
       $("#snapshot-filmstrip").hidden = true;
 
       window.emit(EVENTS.SNAPSHOTS_LIST_CLEARED);
-    })();
+    });
   },
 
   /**
@@ -270,7 +270,7 @@ var SnapshotsListView = extend(WidgetMethods, {
   /**
    * Begins recording an animation.
    */
-  async _recordAnimation() {
+  _recordAnimation: Task.async(function* () {
     if (this._recording) {
       return;
     }
@@ -279,7 +279,7 @@ var SnapshotsListView = extend(WidgetMethods, {
 
     setNamedTimeout("canvas-actor-recording", CANVAS_ACTOR_RECORDING_ATTEMPT, this._stopRecordingAnimation);
 
-    await DevToolsUtils.waitForTime(SNAPSHOT_START_RECORDING_DELAY);
+    yield DevToolsUtils.waitForTime(SNAPSHOT_START_RECORDING_DELAY);
     window.emit(EVENTS.SNAPSHOT_RECORDING_STARTED);
 
     gFront.recordAnimationFrame().then(snapshot => {
@@ -292,20 +292,20 @@ var SnapshotsListView = extend(WidgetMethods, {
 
     // Wait another delay before reenabling the button to stop the recording
     // if a recording is not found.
-    await DevToolsUtils.waitForTime(SNAPSHOT_START_RECORDING_DELAY);
+    yield DevToolsUtils.waitForTime(SNAPSHOT_START_RECORDING_DELAY);
     this._enableRecordButton();
-  },
+  }),
 
   /**
    * Stops recording animation. Called when a click on the stopwatch occurs during a recording,
    * or if a recording times out.
    */
-  async _stopRecordingAnimation() {
+  _stopRecordingAnimation: Task.async(function* () {
     clearNamedTimeout("canvas-actor-recording");
-    let actorCanStop = await gTarget.actorHasMethod("canvas", "stopRecordingAnimationFrame");
+    let actorCanStop = yield gTarget.actorHasMethod("canvas", "stopRecordingAnimationFrame");
 
     if (actorCanStop) {
-      await gFront.stopRecordingAnimationFrame();
+      yield gFront.stopRecordingAnimationFrame();
     }
     // If actor does not have the method to stop recording (Fx39+),
     // manually call the record failure method. This will call a connection failure
@@ -318,16 +318,16 @@ var SnapshotsListView = extend(WidgetMethods, {
     this._recording = false;
     $("#record-snapshot").removeAttribute("checked");
     this._enableRecordButton();
-  },
+  }),
 
   /**
    * Resolves from the front's recordAnimationFrame to setup the interface with the screenshots.
    */
-  async _onRecordSuccess(snapshotActor) {
+  _onRecordSuccess: Task.async(function* (snapshotActor) {
     // Clear bail-out case if frame found in CANVAS_ACTOR_RECORDING_ATTEMPT milliseconds
     clearNamedTimeout("canvas-actor-recording");
     let snapshotItem = this.getItemAtIndex(this.itemCount - 1);
-    let snapshotOverview = await snapshotActor.getOverview();
+    let snapshotOverview = yield snapshotActor.getOverview();
     this.customizeSnapshot(snapshotItem, snapshotActor, snapshotOverview);
 
     this._recording = false;
@@ -335,7 +335,7 @@ var SnapshotsListView = extend(WidgetMethods, {
 
     window.emit(EVENTS.SNAPSHOT_RECORDING_COMPLETED);
     window.emit(EVENTS.SNAPSHOT_RECORDING_FINISHED);
-  },
+  }),
 
   /**
    * Called as a reject from the front's recordAnimationFrame.
@@ -408,7 +408,7 @@ var SnapshotsListView = extend(WidgetMethods, {
 
     // Start serializing all the function call actors for the specified snapshot,
     // while the nsIFilePicker dialog is being opened. Snappy.
-    let serialized = (async function () {
+    let serialized = Task.spawn(function* () {
       let data = {
         fileType: CALLS_LIST_SERIALIZER_IDENTIFIER,
         version: CALLS_LIST_SERIALIZER_VERSION,
@@ -421,7 +421,7 @@ var SnapshotsListView = extend(WidgetMethods, {
       let screenshot = snapshotItem.attachment.screenshot;
 
       // Prepare all the function calls for serialization.
-      await DevToolsUtils.yieldingEach(functionCalls, (call, i) => {
+      yield DevToolsUtils.yieldingEach(functionCalls, (call, i) => {
         let { type, name, file, line, timestamp, argsPreview, callerPreview } = call;
         return call.getDetails().then(({ stack }) => {
           data.calls[i] = {
@@ -438,7 +438,7 @@ var SnapshotsListView = extend(WidgetMethods, {
       });
 
       // Prepare all the thumbnails for serialization.
-      await DevToolsUtils.yieldingEach(thumbnails, (thumbnail, i) => {
+      yield DevToolsUtils.yieldingEach(thumbnails, (thumbnail, i) => {
         let { index, width, height, flipped, pixels } = thumbnail;
         data.thumbnails.push({ index, width, height, flipped, pixels });
       });
@@ -453,7 +453,7 @@ var SnapshotsListView = extend(WidgetMethods, {
 
       converter.charset = "UTF-8";
       return converter.convertToInputStream(string);
-    })();
+    });
 
     // Open the nsIFilePicker and wait for the function call actors to finish
     // being serialized, in order to save the generated JSON data to disk.
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-01.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-01.js
index 384f447a4b3d..9b6ee4e4fc73 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-01.js
@@ -6,12 +6,12 @@
  * You can also use this initialization format as a template for other tests.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCallWatcherBackend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCallWatcherBackend(SIMPLE_CANVAS_URL);
 
   ok(target, "Should have a target available.");
   ok(front, "Should have a protocol front available.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-02.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-02.js
index 1fc488941356..eb8a8f5f7cc7 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-02.js
@@ -6,12 +6,12 @@
  * and that their stack is successfully retrieved.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCallWatcherBackend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCallWatcherBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({
+  yield front.setup({
     tracedGlobals: ["CanvasRenderingContext2D", "WebGLRenderingContext"],
     startRecording: true,
     performReload: true,
@@ -19,13 +19,13 @@ async function ifTestingSupported() {
   });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
   // Allow the content to execute some functions.
-  await waitForTick();
+  yield waitForTick();
 
-  let functionCalls = await front.pauseRecording();
+  let functionCalls = yield front.pauseRecording();
   ok(functionCalls,
     "An array of function call actors was sent after reloading.");
   ok(functionCalls.length > 0,
@@ -45,7 +45,7 @@ async function ifTestingSupported() {
   is(functionCalls[0].argsPreview, "0, 0, 128, 128",
     "The called function's args preview is correct.");
 
-  let details = await functionCalls[1].getDetails();
+  let details = yield functionCalls[1].getDetails();
   ok(details,
     "The first called function has some details available.");
 
@@ -73,6 +73,6 @@ async function ifTestingSupported() {
   is(details.stack[2].line, 33,
     "The called function's stack is correct (3.3).");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-03.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-03.js
index 3b4ac80c61ad..8a8a63780e5a 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-03.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-03.js
@@ -6,22 +6,22 @@
  * for a canvas context.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
+  let snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
 
-  let animationOverview = await snapshotActor.getOverview();
+  let animationOverview = yield snapshotActor.getOverview();
   ok(snapshotActor,
     "An animation overview could be retrieved after recording.");
 
@@ -70,6 +70,6 @@ async function ifTestingSupported() {
   is(functionCalls[7].callerPreview, "Object",
     "The last called function's caller preview is correct.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-04.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-04.js
index c8c8d3b01d1e..d3c7d7661940 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-04.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-04.js
@@ -6,22 +6,22 @@
  * the correct thumbnails.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
+  let snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
 
-  let animationOverview = await snapshotActor.getOverview();
+  let animationOverview = yield snapshotActor.getOverview();
   ok(animationOverview,
     "An animation overview could be retrieved after recording.");
 
@@ -75,7 +75,7 @@ async function ifTestingSupported() {
   is([].find.call(Uint32(thumbnails[3].pixels), e => e > 0), 4290822336,
     "The fourth thumbnail's pixels seem to not be completely transparent.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-05.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-05.js
index a162016ec0a4..e13dab9a4112 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-05.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-05.js
@@ -6,22 +6,22 @@
  * the correct "end result" screenshot.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
+  let snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
 
-  let animationOverview = await snapshotActor.getOverview();
+  let animationOverview = yield snapshotActor.getOverview();
   ok(snapshotActor,
     "An animation overview could be retrieved after recording.");
 
@@ -40,7 +40,7 @@ async function ifTestingSupported() {
   is([].find.call(Uint32(screenshot.pixels), e => e > 0), 4290822336,
     "The screenshot's pixels seem to not be completely transparent.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-06.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-06.js
index 96a9f7d1af18..511db6667864 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-06.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-06.js
@@ -5,19 +5,19 @@
  * Tests if screenshots for arbitrary draw calls are generated properly.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_CANVAS_TRANSPARENT_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_CANVAS_TRANSPARENT_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
-  let animationOverview = await snapshotActor.getOverview();
+  let snapshotActor = yield front.recordAnimationFrame();
+  let animationOverview = yield snapshotActor.getOverview();
 
   let functionCalls = animationOverview.calls;
   ok(functionCalls,
@@ -34,10 +34,10 @@ async function ifTestingSupported() {
   is(functionCalls[6].name, "fillRect",
     "The fourth called function's name is correct.");
 
-  let firstDrawCallScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[0]);
-  let secondDrawCallScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[2]);
-  let thirdDrawCallScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[4]);
-  let fourthDrawCallScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[6]);
+  let firstDrawCallScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[0]);
+  let secondDrawCallScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[2]);
+  let thirdDrawCallScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[4]);
+  let fourthDrawCallScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[6]);
 
   ok(firstDrawCallScreenshot,
     "The first draw call has a screenshot attached.");
@@ -90,7 +90,7 @@ async function ifTestingSupported() {
   isnot(thirdDrawCallScreenshot.pixels, fourthDrawCallScreenshot.pixels,
     "The screenshots taken on consecutive draw calls are different (3).");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-07.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-07.js
index 61fc775d3342..8e6c8c25abad 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-07.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-07.js
@@ -6,19 +6,19 @@
  * by deferring the the most recent previous draw-call.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
-  let animationOverview = await snapshotActor.getOverview();
+  let snapshotActor = yield front.recordAnimationFrame();
+  let animationOverview = yield snapshotActor.getOverview();
 
   let functionCalls = animationOverview.calls;
   ok(functionCalls,
@@ -26,9 +26,9 @@ async function ifTestingSupported() {
   is(functionCalls.length, 8,
     "The number of function call actors is correct.");
 
-  let firstNonDrawCall = await functionCalls[1].getDetails();
-  let secondNonDrawCall = await functionCalls[3].getDetails();
-  let lastNonDrawCall = await functionCalls[7].getDetails();
+  let firstNonDrawCall = yield functionCalls[1].getDetails();
+  let secondNonDrawCall = yield functionCalls[3].getDetails();
+  let lastNonDrawCall = yield functionCalls[7].getDetails();
 
   is(firstNonDrawCall.name, "fillStyle",
     "The first non-draw function's name is correct.");
@@ -37,9 +37,9 @@ async function ifTestingSupported() {
   is(lastNonDrawCall.name, "requestAnimationFrame",
     "The last non-draw function's name is correct.");
 
-  let firstScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[1]);
-  let secondScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[3]);
-  let lastScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[7]);
+  let firstScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[1]);
+  let secondScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[3]);
+  let lastScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[7]);
 
   ok(firstScreenshot,
     "A screenshot was successfully retrieved for the first non-draw function.");
@@ -48,7 +48,7 @@ async function ifTestingSupported() {
   ok(lastScreenshot,
     "A screenshot was successfully retrieved for the last non-draw function.");
 
-  let firstActualScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[0]);
+  let firstActualScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[0]);
   ok(sameArray(firstScreenshot.pixels, firstActualScreenshot.pixels),
     "The screenshot for the first non-draw function is correct.");
   is(firstScreenshot.width, 128,
@@ -56,7 +56,7 @@ async function ifTestingSupported() {
   is(firstScreenshot.height, 128,
     "The screenshot for the first non-draw function has the correct height.");
 
-  let secondActualScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[2]);
+  let secondActualScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[2]);
   ok(sameArray(secondScreenshot.pixels, secondActualScreenshot.pixels),
     "The screenshot for the second non-draw function is correct.");
   is(secondScreenshot.width, 128,
@@ -64,7 +64,7 @@ async function ifTestingSupported() {
   is(secondScreenshot.height, 128,
     "The screenshot for the second non-draw function has the correct height.");
 
-  let lastActualScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[6]);
+  let lastActualScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[6]);
   ok(sameArray(lastScreenshot.pixels, lastActualScreenshot.pixels),
     "The screenshot for the last non-draw function is correct.");
   is(lastScreenshot.width, 128,
@@ -77,7 +77,7 @@ async function ifTestingSupported() {
   ok(!sameArray(secondScreenshot.pixels, lastScreenshot.pixels),
     "The screenshots taken on consecutive draw calls are different (2).");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-08.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-08.js
index a6f3a336aa1f..f3aeda1a9a5b 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-08.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-08.js
@@ -6,19 +6,19 @@
  * forms if the method's signature does not expect an enum. Bug 999687.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_BITMASKS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_BITMASKS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
-  let animationOverview = await snapshotActor.getOverview();
+  let snapshotActor = yield front.recordAnimationFrame();
+  let animationOverview = yield snapshotActor.getOverview();
   let functionCalls = animationOverview.calls;
 
   is(functionCalls[0].name, "clearRect",
@@ -31,6 +31,6 @@ async function ifTestingSupported() {
   is(functionCalls[2].argsPreview, "0, 0, 1, 1",
     "The fillRect called function's args preview is not casted to enums.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-09.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-09.js
index 040ae96c73f9..d123e3319f7c 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-09.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-09.js
@@ -6,19 +6,19 @@
  * forms if the method's signature does not expect an enum. Bug 999687.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(WEBGL_ENUM_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(WEBGL_ENUM_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
-  let animationOverview = await snapshotActor.getOverview();
+  let snapshotActor = yield front.recordAnimationFrame();
+  let animationOverview = yield snapshotActor.getOverview();
   let functionCalls = animationOverview.calls;
 
   is(functionCalls[0].name, "clear",
@@ -31,6 +31,6 @@ async function ifTestingSupported() {
   is(functionCalls[1].argsPreview, "TEXTURE_2D, null",
     "The bits passed into `gl.bindTexture` have been cast to their enum values.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-10.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-10.js
index e4f420247450..35cefc515444 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-10.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-10.js
@@ -6,23 +6,23 @@
  * after generating screenshots using the actor.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(WEBGL_BINDINGS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(WEBGL_BINDINGS_URL);
   loadFrameScriptUtils();
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
-  let animationOverview = await snapshotActor.getOverview();
+  let snapshotActor = yield front.recordAnimationFrame();
+  let animationOverview = yield snapshotActor.getOverview();
   let functionCalls = animationOverview.calls;
 
-  let firstScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[0]);
+  let firstScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[0]);
   is(firstScreenshot.index, -1,
     "The first screenshot didn't encounter any draw call.");
   is(firstScreenshot.scaling, 0.25,
@@ -36,29 +36,29 @@ async function ifTestingSupported() {
   is(firstScreenshot.pixels.length, 0,
     "The first screenshot should be empty.");
 
-  is((await evalInDebuggee("gl.getParameter(gl.FRAMEBUFFER_BINDING) === customFramebuffer")),
+  is((yield evalInDebuggee("gl.getParameter(gl.FRAMEBUFFER_BINDING) === customFramebuffer")),
     true,
     "The debuggee's gl context framebuffer wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.RENDERBUFFER_BINDING) === customRenderbuffer")),
+  is((yield evalInDebuggee("gl.getParameter(gl.RENDERBUFFER_BINDING) === customRenderbuffer")),
     true,
     "The debuggee's gl context renderbuffer wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.TEXTURE_BINDING_2D) === customTexture")),
+  is((yield evalInDebuggee("gl.getParameter(gl.TEXTURE_BINDING_2D) === customTexture")),
     true,
     "The debuggee's gl context texture binding wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[0]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[0]")),
     128,
     "The debuggee's gl context viewport's left coord. wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[1]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[1]")),
     256,
     "The debuggee's gl context viewport's left coord. wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[2]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[2]")),
     384,
     "The debuggee's gl context viewport's left coord. wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[3]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[3]")),
     512,
     "The debuggee's gl context viewport's left coord. wasn't changed.");
 
-  let secondScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[1]);
+  let secondScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[1]);
   is(secondScreenshot.index, 1,
     "The second screenshot has the correct index.");
   is(secondScreenshot.width, CanvasFront.WEBGL_SCREENSHOT_MAX_HEIGHT,
@@ -80,28 +80,28 @@ async function ifTestingSupported() {
   is(secondScreenshot.pixels[3], 255,
     "The second screenshot has the correct alpha component.");
 
-  is((await evalInDebuggee("gl.getParameter(gl.FRAMEBUFFER_BINDING) === customFramebuffer")),
+  is((yield evalInDebuggee("gl.getParameter(gl.FRAMEBUFFER_BINDING) === customFramebuffer")),
     true,
     "The debuggee's gl context framebuffer still wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.RENDERBUFFER_BINDING) === customRenderbuffer")),
+  is((yield evalInDebuggee("gl.getParameter(gl.RENDERBUFFER_BINDING) === customRenderbuffer")),
     true,
     "The debuggee's gl context renderbuffer still wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.TEXTURE_BINDING_2D) === customTexture")),
+  is((yield evalInDebuggee("gl.getParameter(gl.TEXTURE_BINDING_2D) === customTexture")),
     true,
     "The debuggee's gl context texture binding still wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[0]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[0]")),
     128,
     "The debuggee's gl context viewport's left coord. still wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[1]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[1]")),
     256,
     "The debuggee's gl context viewport's left coord. still wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[2]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[2]")),
     384,
     "The debuggee's gl context viewport's left coord. still wasn't changed.");
-  is((await evalInDebuggee("gl.getParameter(gl.VIEWPORT)[3]")),
+  is((yield evalInDebuggee("gl.getParameter(gl.VIEWPORT)[3]")),
     512,
     "The debuggee's gl context viewport's left coord. still wasn't changed.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-11.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-11.js
index 9fe1f19e6fe7..a1e5010b6d48 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-11.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-11.js
@@ -6,22 +6,22 @@
  * for a canvas context, and that the generated screenshots are correct.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(SET_TIMEOUT_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(SET_TIMEOUT_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
+  let snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
 
-  let animationOverview = await snapshotActor.getOverview();
+  let animationOverview = yield snapshotActor.getOverview();
   ok(snapshotActor,
     "An animation overview could be retrieved after recording.");
 
@@ -70,9 +70,9 @@ async function ifTestingSupported() {
   is(functionCalls[7].callerPreview, "Object",
     "The last called function's caller preview is correct.");
 
-  let firstNonDrawCall = await functionCalls[1].getDetails();
-  let secondNonDrawCall = await functionCalls[3].getDetails();
-  let lastNonDrawCall = await functionCalls[7].getDetails();
+  let firstNonDrawCall = yield functionCalls[1].getDetails();
+  let secondNonDrawCall = yield functionCalls[3].getDetails();
+  let lastNonDrawCall = yield functionCalls[7].getDetails();
 
   is(firstNonDrawCall.name, "fillStyle",
     "The first non-draw function's name is correct.");
@@ -81,9 +81,9 @@ async function ifTestingSupported() {
   is(lastNonDrawCall.name, "setTimeout",
     "The last non-draw function's name is correct.");
 
-  let firstScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[1]);
-  let secondScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[3]);
-  let lastScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[7]);
+  let firstScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[1]);
+  let secondScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[3]);
+  let lastScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[7]);
 
   ok(firstScreenshot,
     "A screenshot was successfully retrieved for the first non-draw function.");
@@ -92,7 +92,7 @@ async function ifTestingSupported() {
   ok(lastScreenshot,
     "A screenshot was successfully retrieved for the last non-draw function.");
 
-  let firstActualScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[0]);
+  let firstActualScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[0]);
   ok(sameArray(firstScreenshot.pixels, firstActualScreenshot.pixels),
     "The screenshot for the first non-draw function is correct.");
   is(firstScreenshot.width, 128,
@@ -100,7 +100,7 @@ async function ifTestingSupported() {
   is(firstScreenshot.height, 128,
     "The screenshot for the first non-draw function has the correct height.");
 
-  let secondActualScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[2]);
+  let secondActualScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[2]);
   ok(sameArray(secondScreenshot.pixels, secondActualScreenshot.pixels),
     "The screenshot for the second non-draw function is correct.");
   is(secondScreenshot.width, 128,
@@ -108,7 +108,7 @@ async function ifTestingSupported() {
   is(secondScreenshot.height, 128,
     "The screenshot for the second non-draw function has the correct height.");
 
-  let lastActualScreenshot = await snapshotActor.generateScreenshotFor(functionCalls[6]);
+  let lastActualScreenshot = yield snapshotActor.generateScreenshotFor(functionCalls[6]);
   ok(sameArray(lastScreenshot.pixels, lastActualScreenshot.pixels),
     "The screenshot for the last non-draw function is correct.");
   is(lastScreenshot.width, 128,
@@ -121,7 +121,7 @@ async function ifTestingSupported() {
   ok(!sameArray(secondScreenshot.pixels, lastScreenshot.pixels),
     "The screenshots taken on consecutive draw calls are different (2).");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-12.js b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-12.js
index 8584974159df..2b8daa215c80 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-actor-test-12.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-actor-test-12.js
@@ -6,24 +6,24 @@
  * in the event no rAF loop is found.
  */
 
-async function ifTestingSupported() {
-  let { target, front } = await initCanvasDebuggerBackend(NO_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, front } = yield initCanvasDebuggerBackend(NO_CANVAS_URL);
   loadFrameScriptUtils();
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
   let startRecording = front.recordAnimationFrame();
-  await front.stopRecordingAnimationFrame();
+  yield front.stopRecordingAnimationFrame();
 
-  ok(!(await startRecording),
+  ok(!(yield startRecording),
     "recordAnimationFrame() does not return a SnapshotActor when cancelled.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-highlight.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-highlight.js
index 554ba2b2b01d..2270f0ccf7a1 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-highlight.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-highlight.js
@@ -5,16 +5,16 @@
  * Tests if certain function calls are properly highlighted in the UI.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   is(CallsListView.itemCount, 8,
     "All the function calls should now be displayed in the UI.");
@@ -36,6 +36,6 @@ async function ifTestingSupported() {
   is($(".call-item-view", CallsListView.getItemAtIndex(7).target).hasAttribute("draw-call"), false,
     "The eigth item's node should not have a draw-call attribute.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-list.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-list.js
index 9c384c9cab7b..5f9ce876f512 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-list.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-list.js
@@ -6,16 +6,16 @@
  * are properly displayed in the UI.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   is(CallsListView.itemCount, 8,
     "All the function calls should now be displayed in the UI.");
@@ -65,6 +65,6 @@ async function ifTestingSupported() {
       "The item's location label has the correct text.");
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-search.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-search.js
index 998ccff31d7b..e865df391715 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-search.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-search.js
@@ -5,17 +5,17 @@
  * Tests if filtering the items in the call list works properly.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
   let searchbox = $("#calls-searchbox");
 
-  await reload(target);
+  yield reload(target);
 
   let firstRecordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([firstRecordingFinished, callListPopulated]);
+  yield promise.all([firstRecordingFinished, callListPopulated]);
 
   is(searchbox.value, "",
     "The searchbox should be initially empty.");
@@ -47,10 +47,10 @@ async function ifTestingSupported() {
   callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
 
   SnapshotsListView._onRecordButtonClick();
-  await secondRecordingFinished;
+  yield secondRecordingFinished;
 
   SnapshotsListView.selectedIndex = 1;
-  await callListPopulated;
+  yield callListPopulated;
 
   is(searchbox.value, "clear",
     "The searchbox should still contain the 'clear' string.");
@@ -67,6 +67,6 @@ async function ifTestingSupported() {
   is(CallsListView.visibleItems.length, 8,
     "All the items should be initially visible again in the calls list.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-01.js
index 19d5494289de..964683c84f71 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-01.js
@@ -7,20 +7,20 @@
 
 // Force the old debugger UI since it's directly used (see Bug 1301705)
 Services.prefs.setBoolPref("devtools.debugger.new-debugger-frontend", false);
-registerCleanupFunction(function() {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.debugger.new-debugger-frontend");
 });
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_DEEP_STACK_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_DEEP_STACK_URL);
   let { window, $, $all, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   let callItem = CallsListView.getItemAtIndex(2);
   let locationLink = $(".call-item-location", callItem.target);
@@ -30,7 +30,7 @@ async function ifTestingSupported() {
 
   let callStackDisplayed = once(window, EVENTS.CALL_STACK_DISPLAYED);
   EventUtils.sendMouseEvent({ type: "mousedown" }, locationLink, window);
-  await callStackDisplayed;
+  yield callStackDisplayed;
 
   isnot($(".call-item-stack", callItem.target), null,
     "There should be a stack container available now for the draw call.");
@@ -67,9 +67,9 @@ async function ifTestingSupported() {
 
   let jumpedToSource = once(window, EVENTS.SOURCE_SHOWN_IN_JS_DEBUGGER);
   EventUtils.sendMouseEvent({ type: "mousedown" }, $(".call-item-stack-fn-location", callItem.target));
-  await jumpedToSource;
+  yield jumpedToSource;
 
-  let toolbox = await gDevTools.getToolbox(target);
+  let toolbox = yield gDevTools.getToolbox(target);
   let { panelWin: { DebuggerView: view } } = toolbox.getPanel("jsdebugger");
 
   is(view.Sources.selectedValue, getSourceActor(view.Sources, SIMPLE_CANVAS_DEEP_STACK_URL),
@@ -77,6 +77,6 @@ async function ifTestingSupported() {
   is(view.editor.getCursor().line, 25,
     "The expected source line is highlighted in the debugger.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-02.js
index 01b719de4cc2..9b5c65839c00 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-02.js
@@ -8,20 +8,20 @@
 
 // Force the old debugger UI since it's directly used (see Bug 1301705)
 Services.prefs.setBoolPref("devtools.debugger.new-debugger-frontend", false);
-registerCleanupFunction(function() {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.debugger.new-debugger-frontend");
 });
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_DEEP_STACK_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_DEEP_STACK_URL);
   let { window, $, $all, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   let callItem = CallsListView.getItemAtIndex(2);
   let locationLink = $(".call-item-location", callItem.target);
@@ -31,7 +31,7 @@ async function ifTestingSupported() {
 
   let callStackDisplayed = once(window, EVENTS.CALL_STACK_DISPLAYED);
   EventUtils.sendMouseEvent({ type: "mousedown" }, locationLink, window);
-  await callStackDisplayed;
+  yield callStackDisplayed;
 
   isnot($(".call-item-stack", callItem.target), null,
     "There should be a stack container available now for the draw call.");
@@ -42,9 +42,9 @@ async function ifTestingSupported() {
 
   let jumpedToSource = once(window, EVENTS.SOURCE_SHOWN_IN_JS_DEBUGGER);
   EventUtils.sendMouseEvent({ type: "mousedown" }, $(".call-item-location", callItem.target));
-  await jumpedToSource;
+  yield jumpedToSource;
 
-  let toolbox = await gDevTools.getToolbox(target);
+  let toolbox = yield gDevTools.getToolbox(target);
   let { panelWin: { DebuggerView: view } } = toolbox.getPanel("jsdebugger");
 
   is(view.Sources.selectedValue, getSourceActor(view.Sources, SIMPLE_CANVAS_DEEP_STACK_URL),
@@ -52,6 +52,6 @@ async function ifTestingSupported() {
   is(view.editor.getCursor().line, 23,
     "The expected source line is highlighted in the debugger.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-03.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-03.js
index 2007194ee502..24780c566102 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-03.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-call-stack-03.js
@@ -6,16 +6,16 @@
  * on a function call item.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_DEEP_STACK_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_DEEP_STACK_URL);
   let { window, $, $all, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   let callItem = CallsListView.getItemAtIndex(2);
   let view = $(".call-item-view", callItem.target);
@@ -30,7 +30,7 @@ async function ifTestingSupported() {
 
   let callStackDisplayed = once(window, EVENTS.CALL_STACK_DISPLAYED);
   EventUtils.sendMouseEvent({ type: "dblclick" }, contents, window);
-  await callStackDisplayed;
+  yield callStackDisplayed;
 
   is(view.hasAttribute("call-stack-populated"), true,
     "The call item's view should have the stack populated now.");
@@ -60,6 +60,6 @@ async function ifTestingSupported() {
   ok($all(".call-item-stack-fn", callItem.target).length >= 4,
      "There should still be at least 4 functions on the stack for the draw call.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-clear.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-clear.js
index fb8b1de7ff02..c800820465ba 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-clear.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-clear.js
@@ -5,16 +5,16 @@
  * Tests if clearing the snapshots list works as expected.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, EVENTS, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let firstRecordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   SnapshotsListView._onRecordButtonClick();
 
-  await firstRecordingFinished;
+  yield firstRecordingFinished;
   ok(true, "Finished recording a snapshot of the animation loop.");
 
   is(SnapshotsListView.itemCount, 1,
@@ -23,7 +23,7 @@ async function ifTestingSupported() {
   let secondRecordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   SnapshotsListView._onRecordButtonClick();
 
-  await secondRecordingFinished;
+  yield secondRecordingFinished;
   ok(true, "Finished recording another snapshot of the animation loop.");
 
   is(SnapshotsListView.itemCount, 2,
@@ -32,12 +32,12 @@ async function ifTestingSupported() {
   let clearingFinished = once(window, EVENTS.SNAPSHOTS_LIST_CLEARED);
   SnapshotsListView._onClearButtonClick();
 
-  await clearingFinished;
+  yield clearingFinished;
   ok(true, "Finished recording all snapshots.");
 
   is(SnapshotsListView.itemCount, 0,
     "There should be no items available in the snapshots list.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-screenshots.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-screenshots.js
index d108735f56e6..e96543e10eda 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-screenshots.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-screenshots.js
@@ -5,17 +5,17 @@
  * Tests if screenshots are properly displayed in the UI.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   let screenshotDisplayed = once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated, screenshotDisplayed]);
+  yield promise.all([recordingFinished, callListPopulated, screenshotDisplayed]);
 
   is($("#screenshot-container").hidden, false,
     "The screenshot container should now be visible.");
@@ -29,6 +29,6 @@ async function ifTestingSupported() {
   ok(window.getComputedStyle($("#screenshot-image")).backgroundImage.includes("#screenshot-rendering"),
     "The screenshot element should have an offscreen canvas element as a background.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-01.js
index 5bc8d30403b7..41e8f7383a41 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-01.js
@@ -5,17 +5,17 @@
  * Tests if thumbnails are properly displayed in the UI.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, $all, EVENTS, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   let thumbnailsDisplayed = once(window, EVENTS.THUMBNAILS_DISPLAYED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated, thumbnailsDisplayed]);
+  yield promise.all([recordingFinished, callListPopulated, thumbnailsDisplayed]);
 
   is($all(".filmstrip-thumbnail").length, 4,
     "There should be 4 thumbnails displayed in the UI.");
@@ -60,6 +60,6 @@ async function ifTestingSupported() {
   is(fourthThumbnail.getAttribute("flipped"), "false",
     "The fourth thumbnail should not be flipped vertically.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-02.js
index 1819658573a7..798bc090bd7a 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-img-thumbnails-02.js
@@ -6,18 +6,18 @@
  * function call items and their respective screenshots.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, $all, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   let thumbnailsDisplayed = once(window, EVENTS.THUMBNAILS_DISPLAYED);
   let screenshotDisplayed = once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([
+  yield promise.all([
     recordingFinished,
     callListPopulated,
     thumbnailsDisplayed,
@@ -30,7 +30,7 @@ async function ifTestingSupported() {
     "There should be no selected item in the calls list view.");
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, $all(".filmstrip-thumbnail")[0], window);
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   info("The first draw call was selected, by clicking the first thumbnail.");
 
   isnot($(".filmstrip-thumbnail[highlighted][index='0']"), null,
@@ -41,7 +41,7 @@ async function ifTestingSupported() {
     "The first draw call should be selected in the calls list view.");
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, $all(".call-item-view")[1], window);
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   info("The second context call was selected, by clicking the second call item.");
 
   isnot($(".filmstrip-thumbnail[highlighted][index='0']"), null,
@@ -52,7 +52,7 @@ async function ifTestingSupported() {
     "The second draw call should be selected in the calls list view.");
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, $all(".call-item-view")[2], window);
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   info("The second draw call was selected, by clicking the third call item.");
 
   isnot($(".filmstrip-thumbnail[highlighted][index='2']"), null,
@@ -62,6 +62,6 @@ async function ifTestingSupported() {
   is(CallsListView.selectedIndex, 2,
     "The second draw call should be selected in the calls list view.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-open.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-open.js
index d33a080f6fee..59c4d4cfb713 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-open.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-open.js
@@ -5,8 +5,8 @@
  * Tests that the frontend UI is properly configured when opening the tool.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { $ } = panel.panelWin;
 
   is($("#snapshots-pane").hasAttribute("hidden"), false,
@@ -36,6 +36,6 @@ async function ifTestingSupported() {
   is($("#debugging-pane-contents").getAttribute("hidden"), "true",
     "The rest of the UI should initially be hidden.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-01.js
index d03dc384f28f..cd0358d3c6e8 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-01.js
@@ -5,11 +5,11 @@
  * Tests whether the frontend behaves correctly while reording a snapshot.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, EVENTS, $, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   is($("#record-snapshot").hasAttribute("checked"), false,
     "The 'record snapshot' button should initially be unchecked.");
@@ -27,7 +27,7 @@ async function ifTestingSupported() {
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   SnapshotsListView._onRecordButtonClick();
 
-  await recordingStarted;
+  yield recordingStarted;
   ok(true, "Started recording a snapshot of the animation loop.");
 
   is($("#record-snapshot").getAttribute("checked"), "true",
@@ -40,7 +40,7 @@ async function ifTestingSupported() {
   is(SnapshotsListView.selectedIndex, -1,
     "There should be no selected item in the snapshots list view yet.");
 
-  await recordingFinished;
+  yield recordingFinished;
   ok(true, "Finished recording a snapshot of the animation loop.");
 
   is($("#record-snapshot").hasAttribute("checked"), false,
@@ -55,6 +55,6 @@ async function ifTestingSupported() {
   is(SnapshotsListView.selectedIndex, 0,
     "There should be one selected item in the snapshots list view now.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-02.js
index 71351082d216..aee63a5746ac 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-02.js
@@ -5,18 +5,18 @@
  * Tests whether the frontend displays a placeholder snapshot while recording.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, EVENTS, L10N, $, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingStarted = once(window, EVENTS.SNAPSHOT_RECORDING_STARTED);
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let recordingSelected = once(window, EVENTS.SNAPSHOT_RECORDING_SELECTED);
   SnapshotsListView._onRecordButtonClick();
 
-  await recordingStarted;
+  yield recordingStarted;
   ok(true, "Started recording a snapshot of the animation loop.");
 
   let item = SnapshotsListView.getItemAtIndex(0);
@@ -47,10 +47,10 @@ async function ifTestingSupported() {
   is($("#debugging-pane-contents").getAttribute("hidden"), "true",
     "The rest of the UI should still be hidden.");
 
-  await recordingFinished;
+  yield recordingFinished;
   ok(true, "Finished recording a snapshot of the animation loop.");
 
-  await recordingSelected;
+  yield recordingSelected;
   ok(true, "Finished selecting a snapshot of the animation loop.");
 
   is($("#reload-notice").getAttribute("hidden"), "true",
@@ -68,6 +68,6 @@ async function ifTestingSupported() {
   is($("#debugging-pane-contents").hasAttribute("hidden"), false,
     "The rest of the UI should now be visible.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-03.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-03.js
index fa747b223388..c3638610ee19 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-03.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-03.js
@@ -6,16 +6,16 @@
  * after finishing recording.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, EVENTS, $, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   SnapshotsListView._onRecordButtonClick();
 
-  await recordingFinished;
+  yield recordingFinished;
   ok(true, "Finished recording a snapshot of the animation loop.");
 
   let item = SnapshotsListView.getItemAtIndex(0);
@@ -32,6 +32,6 @@ async function ifTestingSupported() {
   is($(".snapshot-item-save", item.target).getAttribute("disabled"), "false",
     "The placeholder item's save label should be clickable.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-04.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-04.js
index 588dbc52ea9c..0985267e6617 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-04.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-record-04.js
@@ -8,12 +8,12 @@
  * of its loop, when the recording starts before the rAFs start.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(RAF_BEGIN_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(RAF_BEGIN_URL);
   let { window, EVENTS, gFront, SnapshotsListView } = panel.panelWin;
   loadFrameScriptUtils();
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   SnapshotsListView._onRecordButtonClick();
@@ -21,14 +21,14 @@ async function ifTestingSupported() {
   // Wait until after the recording started to trigger the content.
   // Use the gFront method rather than the SNAPSHOT_RECORDING_STARTED event
   // which triggers before the underlying actor call
-  await waitUntil(async function () { return !(await gFront.isRecording()); });
+  yield waitUntil(function* () { return !(yield gFront.isRecording()); });
 
   // Start animation in content
   evalInDebuggee("start();");
 
-  await recordingFinished;
+  yield recordingFinished;
   ok(true, "Finished recording a snapshot of the animation loop.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-01.js
index e181570f1db5..cf353aa2729b 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-01.js
@@ -5,17 +5,17 @@
  * Tests that the frontend UI is properly reconfigured after reloading.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS } = panel.panelWin;
 
   let reset = once(window, EVENTS.UI_RESET);
   let navigated = reload(target);
 
-  await reset;
+  yield reset;
   ok(true, "The UI was reset after the refresh button was clicked.");
 
-  await navigated;
+  yield navigated;
   ok(true, "The target finished reloading.");
 
   is($("#snapshots-pane").hasAttribute("hidden"), false,
@@ -50,6 +50,6 @@ async function ifTestingSupported() {
   is($("#debugging-pane-contents").getAttribute("hidden"), "true",
     "The rest of the UI should still be hidden.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-02.js
index ab6cce871615..2747fd13f9d7 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-reload-02.js
@@ -5,8 +5,8 @@
  * Tests that the frontend UI is properly reconfigured after reloading.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, $all, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
   is(SnapshotsListView.itemCount, 0,
@@ -21,14 +21,14 @@ async function ifTestingSupported() {
   is($all(".filmstrip-thumbnail").length, 0,
     "There should be no thumbnails initially displayed in the UI (2).");
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   let thumbnailsDisplayed = once(window, EVENTS.THUMBNAILS_DISPLAYED);
   let screenshotDisplayed = once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([
+  yield promise.all([
     recordingFinished,
     callListPopulated,
     thumbnailsDisplayed,
@@ -50,7 +50,7 @@ async function ifTestingSupported() {
   let reset = once(window, EVENTS.UI_RESET);
   let navigated = reload(target);
 
-  await reset;
+  yield reset;
   ok(true, "The UI was reset after the refresh button was clicked.");
 
   is(SnapshotsListView.itemCount, 0,
@@ -62,9 +62,9 @@ async function ifTestingSupported() {
   is($("#screenshot-container").hidden, true,
     "The screenshot should not be displayed in the UI after navigating.");
 
-  await navigated;
+  yield navigated;
   ok(true, "The target finished reloading.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-01.js
index 8d5ca53f4fee..cdce00bd1d30 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-01.js
@@ -5,16 +5,16 @@
  * Tests if the slider in the calls list view works as advertised.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   is(CallsListView.selectedIndex, -1,
     "No item in the function calls list should be initially selected.");
@@ -34,6 +34,6 @@ async function ifTestingSupported() {
   is(CallsListView.selectedIndex, 2,
     "The calls selection should be changed according to the current slider value.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-02.js
index d297e81f338a..18aee4b6cad0 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-slider-02.js
@@ -5,20 +5,20 @@
  * Tests if the slider in the calls list view works as advertised.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, gFront, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   let thumbnailsDisplayed = once(window, EVENTS.THUMBNAILS_DISPLAYED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated, thumbnailsDisplayed]);
+  yield promise.all([recordingFinished, callListPopulated, thumbnailsDisplayed]);
 
   let firstSnapshot = SnapshotsListView.getItemAtIndex(0);
-  let firstSnapshotOverview = await firstSnapshot.attachment.actor.getOverview();
+  let firstSnapshotOverview = yield firstSnapshot.attachment.actor.getOverview();
 
   let thumbnails = firstSnapshotOverview.thumbnails;
   is(thumbnails.length, 4,
@@ -26,55 +26,55 @@ async function ifTestingSupported() {
 
   let thumbnailImageElementSet = waitForMozSetImageElement(window);
   $("#calls-slider").value = 1;
-  let thumbnailPixels = await thumbnailImageElementSet;
+  let thumbnailPixels = yield thumbnailImageElementSet;
 
   ok(sameArray(thumbnailPixels, thumbnails[0].pixels),
     "The screenshot element should have a thumbnail as an immediate background.");
 
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   ok(true, "The full-sized screenshot was displayed for the item at index 1.");
 
   thumbnailImageElementSet = waitForMozSetImageElement(window);
   $("#calls-slider").value = 2;
-  thumbnailPixels = await thumbnailImageElementSet;
+  thumbnailPixels = yield thumbnailImageElementSet;
 
   ok(sameArray(thumbnailPixels, thumbnails[1].pixels),
     "The screenshot element should have a thumbnail as an immediate background.");
 
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   ok(true, "The full-sized screenshot was displayed for the item at index 2.");
 
   thumbnailImageElementSet = waitForMozSetImageElement(window);
   $("#calls-slider").value = 7;
-  thumbnailPixels = await thumbnailImageElementSet;
+  thumbnailPixels = yield thumbnailImageElementSet;
 
   ok(sameArray(thumbnailPixels, thumbnails[3].pixels),
     "The screenshot element should have a thumbnail as an immediate background.");
 
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   ok(true, "The full-sized screenshot was displayed for the item at index 7.");
 
   thumbnailImageElementSet = waitForMozSetImageElement(window);
   $("#calls-slider").value = 4;
-  thumbnailPixels = await thumbnailImageElementSet;
+  thumbnailPixels = yield thumbnailImageElementSet;
 
   ok(sameArray(thumbnailPixels, thumbnails[2].pixels),
     "The screenshot element should have a thumbnail as an immediate background.");
 
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   ok(true, "The full-sized screenshot was displayed for the item at index 4.");
 
   thumbnailImageElementSet = waitForMozSetImageElement(window);
   $("#calls-slider").value = 0;
-  thumbnailPixels = await thumbnailImageElementSet;
+  thumbnailPixels = yield thumbnailImageElementSet;
 
   ok(sameArray(thumbnailPixels, thumbnails[0].pixels),
     "The screenshot element should have a thumbnail as an immediate background.");
 
-  await once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
+  yield once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   ok(true, "The full-sized screenshot was displayed for the item at index 0.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-01.js
index 2aa6701509f1..4dc275282eff 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-01.js
@@ -6,13 +6,13 @@
  * respective to their recorded animation frame.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
-  await recordAndWaitForFirstSnapshot();
+  yield recordAndWaitForFirstSnapshot();
   info("First snapshot recorded.");
 
   is(SnapshotsListView.selectedIndex, 0,
@@ -20,7 +20,7 @@ async function ifTestingSupported() {
   is(CallsListView.selectedIndex, -1,
     "There should be no call item automatically selected in the snapshot.");
 
-  await recordAndWaitForAnotherSnapshot();
+  yield recordAndWaitForAnotherSnapshot();
   info("Second snapshot recorded.");
 
   is(SnapshotsListView.selectedIndex, 0,
@@ -32,7 +32,7 @@ async function ifTestingSupported() {
   let snapshotSelected = waitForSnapshotSelection();
   EventUtils.sendMouseEvent({ type: "mousedown" }, secondSnapshotTarget, window);
 
-  await snapshotSelected;
+  yield snapshotSelected;
   info("Second snapshot selected.");
 
   is(SnapshotsListView.selectedIndex, 1,
@@ -44,7 +44,7 @@ async function ifTestingSupported() {
   let screenshotDisplayed = once(window, EVENTS.CALL_SCREENSHOT_DISPLAYED);
   EventUtils.sendMouseEvent({ type: "mousedown" }, firstDrawCallContents, window);
 
-  await screenshotDisplayed;
+  yield screenshotDisplayed;
   info("First draw call in the second snapshot selected.");
 
   is(SnapshotsListView.selectedIndex, 1,
@@ -56,7 +56,7 @@ async function ifTestingSupported() {
   snapshotSelected = waitForSnapshotSelection();
   EventUtils.sendMouseEvent({ type: "mousedown" }, firstSnapshotTarget, window);
 
-  await snapshotSelected;
+  yield snapshotSelected;
   info("First snapshot re-selected.");
 
   is(SnapshotsListView.selectedIndex, 0,
@@ -88,6 +88,6 @@ async function ifTestingSupported() {
     ]);
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-02.js
index ee3100cbc1dc..27a03fb517d9 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-snapshot-select-02.js
@@ -6,11 +6,11 @@
  * respective to their recorded animation frame.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   SnapshotsListView._onRecordButtonClick();
   let snapshotTarget = SnapshotsListView.getItemAtIndex(0).target;
@@ -23,8 +23,8 @@ async function ifTestingSupported() {
 
   let finished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   SnapshotsListView._onRecordButtonClick();
-  await finished;
+  yield finished;
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stepping.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stepping.js
index 8922c1249c29..d76449b91eff 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stepping.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stepping.js
@@ -5,16 +5,16 @@
  * Tests if the stepping buttons in the call list toolbar work as advertised.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(SIMPLE_CANVAS_URL);
   let { window, $, EVENTS, SnapshotsListView, CallsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let callListPopulated = once(window, EVENTS.CALL_LIST_POPULATED);
   SnapshotsListView._onRecordButtonClick();
-  await promise.all([recordingFinished, callListPopulated]);
+  yield promise.all([recordingFinished, callListPopulated]);
 
   checkSteppingButtons(1, 1, 1, 1);
   is(CallsListView.selectedIndex, -1,
@@ -71,6 +71,6 @@ async function ifTestingSupported() {
     }
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-01.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-01.js
index e8f250d405a8..3a74e4b44ed8 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-01.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-01.js
@@ -5,16 +5,16 @@
  * Tests that you can stop a recording that does not have a rAF cycle.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(NO_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(NO_CANVAS_URL);
   let { window, EVENTS, $, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingStarted = once(window, EVENTS.SNAPSHOT_RECORDING_STARTED);
   SnapshotsListView._onRecordButtonClick();
 
-  await recordingStarted;
+  yield recordingStarted;
 
   is($("#empty-notice").hidden, true, "Empty notice not shown");
   is($("#waiting-notice").hidden, false, "Waiting notice shown");
@@ -23,7 +23,7 @@ async function ifTestingSupported() {
   let recordingCancelled = once(window, EVENTS.SNAPSHOT_RECORDING_CANCELLED);
   SnapshotsListView._onRecordButtonClick();
 
-  await promise.all([recordingFinished, recordingCancelled]);
+  yield promise.all([recordingFinished, recordingCancelled]);
 
   ok(true, "Recording stopped and was considered failed.");
 
@@ -31,6 +31,6 @@ async function ifTestingSupported() {
   is($("#empty-notice").hidden, false, "Empty notice shown");
   is($("#waiting-notice").hidden, true, "Waiting notice not shown");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-02.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-02.js
index c562b931c7ef..b062fbc5e398 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-02.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-02.js
@@ -5,16 +5,16 @@
  * Tests that a recording that does not have a rAF cycle fails after timeout.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(NO_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(NO_CANVAS_URL);
   let { window, EVENTS, $, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingStarted = once(window, EVENTS.SNAPSHOT_RECORDING_STARTED);
   SnapshotsListView._onRecordButtonClick();
 
-  await recordingStarted;
+  yield recordingStarted;
 
   is($("#empty-notice").hidden, true, "Empty notice not shown");
   is($("#waiting-notice").hidden, false, "Waiting notice shown");
@@ -22,7 +22,7 @@ async function ifTestingSupported() {
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let recordingCancelled = once(window, EVENTS.SNAPSHOT_RECORDING_CANCELLED);
 
-  await promise.all([recordingFinished, recordingCancelled]);
+  yield promise.all([recordingFinished, recordingCancelled]);
 
   ok(true, "Recording stopped and was considered failed.");
 
@@ -30,6 +30,6 @@ async function ifTestingSupported() {
   is($("#empty-notice").hidden, false, "Empty notice shown");
   is($("#waiting-notice").hidden, true, "Waiting notice not shown");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-03.js b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-03.js
index 2f0f1b2f67e8..70948311dd74 100644
--- a/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-03.js
+++ b/devtools/client/canvasdebugger/test/browser_canvas-frontend-stop-03.js
@@ -6,16 +6,16 @@
  * after timeout.
  */
 
-async function ifTestingSupported() {
-  let { target, panel } = await initCanvasDebuggerFrontend(RAF_NO_CANVAS_URL);
+function* ifTestingSupported() {
+  let { target, panel } = yield initCanvasDebuggerFrontend(RAF_NO_CANVAS_URL);
   let { window, EVENTS, $, SnapshotsListView } = panel.panelWin;
 
-  await reload(target);
+  yield reload(target);
 
   let recordingStarted = once(window, EVENTS.SNAPSHOT_RECORDING_STARTED);
   SnapshotsListView._onRecordButtonClick();
 
-  await recordingStarted;
+  yield recordingStarted;
 
   is($("#empty-notice").hidden, true, "Empty notice not shown");
   is($("#waiting-notice").hidden, false, "Waiting notice shown");
@@ -23,7 +23,7 @@ async function ifTestingSupported() {
   let recordingFinished = once(window, EVENTS.SNAPSHOT_RECORDING_FINISHED);
   let recordingCancelled = once(window, EVENTS.SNAPSHOT_RECORDING_CANCELLED);
 
-  await promise.all([recordingFinished, recordingCancelled]);
+  yield promise.all([recordingFinished, recordingCancelled]);
 
   ok(true, "Recording stopped and was considered failed.");
 
@@ -31,6 +31,6 @@ async function ifTestingSupported() {
   is($("#empty-notice").hidden, false, "Empty notice shown");
   is($("#waiting-notice").hidden, true, "Waiting notice not shown");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_profiling-canvas.js b/devtools/client/canvasdebugger/test/browser_profiling-canvas.js
index 090381f5744a..75f8da4f395b 100644
--- a/devtools/client/canvasdebugger/test/browser_profiling-canvas.js
+++ b/devtools/client/canvasdebugger/test/browser_profiling-canvas.js
@@ -6,23 +6,23 @@
  * for a canvas context profiling.
  */
 
-async function ifTestingSupported() {
+function* ifTestingSupported() {
   let currentTime = window.performance.now();
-  let { target, front } = await initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
+  let { target, front } = yield initCanvasDebuggerBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
+  let snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
 
-  let animationOverview = await snapshotActor.getOverview();
+  let animationOverview = yield snapshotActor.getOverview();
   ok(animationOverview,
     "An animation overview could be retrieved after recording.");
 
@@ -40,6 +40,6 @@ async function ifTestingSupported() {
     ok(functionCalls[i + 1].timestamp >= functionCalls[i].timestamp, "The timestamp of the called function is correct.");
   }
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/canvasdebugger/test/browser_profiling-webgl.js b/devtools/client/canvasdebugger/test/browser_profiling-webgl.js
index f6aedc162cde..37af83a66162 100644
--- a/devtools/client/canvasdebugger/test/browser_profiling-webgl.js
+++ b/devtools/client/canvasdebugger/test/browser_profiling-webgl.js
@@ -6,24 +6,24 @@
  * for a canvas context profiling.
  */
 
-async function ifTestingSupported() {
+function* ifTestingSupported() {
   let currentTime = window.performance.now();
   info("Start to estimate WebGL drawArrays function.");
-  var { target, front } = await initCanvasDebuggerBackend(WEBGL_DRAW_ARRAYS);
+  var { target, front } = yield initCanvasDebuggerBackend(WEBGL_DRAW_ARRAYS);
 
   let navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  let snapshotActor = await front.recordAnimationFrame();
+  let snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
 
-  let animationOverview = await snapshotActor.getOverview();
+  let animationOverview = yield snapshotActor.getOverview();
   ok(animationOverview,
     "An animation overview could be retrieved after recording.");
 
@@ -39,24 +39,24 @@ async function ifTestingSupported() {
   is(animationOverview.primitive.points, 4, "The count of points is correct.");
   is(animationOverview.primitive.lines, 8, "The count of lines is correct.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 
   info("Start to estimate WebGL drawElements function.");
-  var { target, front } = await initCanvasDebuggerBackend(WEBGL_DRAW_ELEMENTS);
+  var { target, front } = yield initCanvasDebuggerBackend(WEBGL_DRAW_ELEMENTS);
 
   navigated = once(target, "navigate");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  snapshotActor = await front.recordAnimationFrame();
+  snapshotActor = yield front.recordAnimationFrame();
   ok(snapshotActor,
     "A snapshot actor was sent after recording.");
   
-  animationOverview = await snapshotActor.getOverview();
+  animationOverview = yield snapshotActor.getOverview();
   ok(animationOverview,
     "An animation overview could be retrieved after recording.");
   
@@ -72,7 +72,7 @@ async function ifTestingSupported() {
   is(animationOverview.primitive.points, 4, "The count of points is correct.");
   is(animationOverview.primitive.lines, 8, "The count of lines is correct.");
   
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
 
diff --git a/devtools/client/canvasdebugger/test/head.js b/devtools/client/canvasdebugger/test/head.js
index 28c589343e19..edcadc3a1437 100644
--- a/devtools/client/canvasdebugger/test/head.js
+++ b/devtools/client/canvasdebugger/test/head.js
@@ -68,13 +68,9 @@ function ifTestingUnsupported() {
   finish();
 }
 
-async function test() {
+function test() {
   let generator = isTestingSupported() ? ifTestingSupported : ifTestingUnsupported;
-  try {
-    await generator();
-  } catch(e) {
-    handleError(e);
-  }
+  Task.spawn(generator).catch(handleError);
 }
 
 function createCanvas() {
@@ -118,46 +114,46 @@ function initCallWatcherBackend(aUrl) {
   info("Initializing a call watcher front.");
   initServer();
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     let front = new CallWatcherFront(target.client, target.form);
     return { target, front };
-  })();
+  });
 }
 
 function initCanvasDebuggerBackend(aUrl) {
   info("Initializing a canvas debugger front.");
   initServer();
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     let front = new CanvasFront(target.client, target.form);
     return { target, front };
-  })();
+  });
 }
 
 function initCanvasDebuggerFrontend(aUrl) {
   info("Initializing a canvas debugger pane.");
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     Services.prefs.setBoolPref("devtools.canvasdebugger.enabled", true);
-    let toolbox = await gDevTools.showToolbox(target, "canvasdebugger");
+    let toolbox = yield gDevTools.showToolbox(target, "canvasdebugger");
     let panel = toolbox.getCurrentPanel();
     return { target, panel };
-  })();
+  });
 }
 
 function teardown({target}) {
diff --git a/devtools/client/commandline/test/head.js b/devtools/client/commandline/test/head.js
index c947a06e08f2..8dc98fcea1a6 100644
--- a/devtools/client/commandline/test/head.js
+++ b/devtools/client/commandline/test/head.js
@@ -12,7 +12,6 @@ const TEST_BASE_HTTPS = "https://example.com/browser/devtools/client/commandline
 
 var { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
 var flags = require("devtools/shared/flags");
-var { Task } = require("devtools/shared/task");
 
 // Import the GCLI test helper
 var testDir = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
diff --git a/devtools/client/debugger/new/test/mochitest/head.js b/devtools/client/debugger/new/test/mochitest/head.js
index c423fd18e933..89517be3c1f2 100644
--- a/devtools/client/debugger/new/test/mochitest/head.js
+++ b/devtools/client/debugger/new/test/mochitest/head.js
@@ -38,7 +38,6 @@ Services.scriptloader.loadSubScript(
   this
 );
 var { Toolbox } = require("devtools/client/framework/toolbox");
-var { Task } = require("devtools/shared/task");
 const sourceUtils = {
   isLoaded: source => source.get("loadedState") === "loaded"
 };
diff --git a/devtools/client/debugger/test/mochitest/head.js b/devtools/client/debugger/test/mochitest/head.js
index c431bf16c460..b06ca42ef1c8 100644
--- a/devtools/client/debugger/test/mochitest/head.js
+++ b/devtools/client/debugger/test/mochitest/head.js
@@ -21,7 +21,6 @@ var ObjectClient = require("devtools/shared/client/object-client");
 var { AddonManager } = ChromeUtils.import("resource://gre/modules/AddonManager.jsm", {});
 var EventEmitter = require("devtools/shared/old-event-emitter");
 var { Toolbox } = require("devtools/client/framework/toolbox");
-var { Task } = require("devtools/shared/task");
 
 const chromeRegistry = Cc["@mozilla.org/chrome/chrome-registry;1"].getService(Ci.nsIChromeRegistry);
 
diff --git a/devtools/client/dom/dom-panel.js b/devtools/client/dom/dom-panel.js
index f4e650850dc0..364e5cc3c80b 100644
--- a/devtools/client/dom/dom-panel.js
+++ b/devtools/client/dom/dom-panel.js
@@ -10,6 +10,7 @@ const ObjectClient = require("devtools/shared/client/object-client");
 
 const defer = require("devtools/shared/defer");
 const EventEmitter = require("devtools/shared/old-event-emitter");
+const { Task } = require("devtools/shared/task");
 
 /**
  * This object represents DOM panel. It's responsibility is to
@@ -35,7 +36,7 @@ DomPanel.prototype = {
    * @return object
    *         A promise that is resolved when the DOM panel completes opening.
    */
-  async open() {
+  open: Task.async(function* () {
     if (this._opening) {
       return this._opening;
     }
@@ -45,7 +46,7 @@ DomPanel.prototype = {
 
     // Local monitoring needs to make the target remote.
     if (!this.target.isRemote) {
-      await this.target.makeRemote();
+      yield this.target.makeRemote();
     }
 
     this.initialize();
@@ -55,7 +56,7 @@ DomPanel.prototype = {
     deferred.resolve(this);
 
     return this._opening;
-  },
+  }),
 
   // Initialization
 
@@ -77,7 +78,7 @@ DomPanel.prototype = {
     this.shouldRefresh = true;
   },
 
-  async destroy() {
+  destroy: Task.async(function* () {
     if (this._destroying) {
       return this._destroying;
     }
@@ -92,7 +93,7 @@ DomPanel.prototype = {
 
     deferred.resolve();
     return this._destroying;
-  },
+  }),
 
   // Events
 
diff --git a/devtools/client/dom/test/browser_dom_array.js b/devtools/client/dom/test/browser_dom_array.js
index beb7533f8290..2813af320320 100644
--- a/devtools/client/dom/test/browser_dom_array.js
+++ b/devtools/client/dom/test/browser_dom_array.js
@@ -14,13 +14,13 @@ const TEST_ARRAY = [
 /**
  * Basic test that checks content of the DOM panel.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test DOM Panel Array Expansion started");
 
-  let { panel } = await addTestTab(TEST_PAGE_URL);
+  let { panel } = yield addTestTab(TEST_PAGE_URL);
 
   // Expand specified row and wait till children are displayed.
-  await expandRow(panel, "_a");
+  yield expandRow(panel, "_a");
 
   // Verify that children is displayed now.
   let childRows = getAllRowsForLabel(panel, "_a");
diff --git a/devtools/client/dom/test/browser_dom_basic.js b/devtools/client/dom/test/browser_dom_basic.js
index 7e783c44173d..2b76fe0fec9c 100644
--- a/devtools/client/dom/test/browser_dom_basic.js
+++ b/devtools/client/dom/test/browser_dom_basic.js
@@ -10,13 +10,13 @@ const TEST_PAGE_URL = URL_ROOT + "page_basic.html";
 /**
  * Basic test that checks content of the DOM panel.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test DOM panel basic started");
 
-  let { panel } = await addTestTab(TEST_PAGE_URL);
+  let { panel } = yield addTestTab(TEST_PAGE_URL);
 
   // Expand specified row and wait till children are displayed.
-  await expandRow(panel, "_a");
+  yield expandRow(panel, "_a");
 
   // Verify that child is displayed now.
   let childRow = getRowByLabel(panel, "_data");
diff --git a/devtools/client/dom/test/browser_dom_refresh.js b/devtools/client/dom/test/browser_dom_refresh.js
index 3c00ab34344f..9fdc6aa7f664 100644
--- a/devtools/client/dom/test/browser_dom_refresh.js
+++ b/devtools/client/dom/test/browser_dom_refresh.js
@@ -10,14 +10,14 @@ const TEST_PAGE_URL = URL_ROOT + "page_basic.html";
 /**
  * Basic test that checks the Refresh action in DOM panel.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test DOM panel basic started");
 
-  let { panel } = await addTestTab(TEST_PAGE_URL);
+  let { panel } = yield addTestTab(TEST_PAGE_URL);
 
   // Create a new variable in the page scope and refresh the panel.
-  await evaluateJSAsync(panel, "var _b = 10");
-  await refreshPanel(panel);
+  yield evaluateJSAsync(panel, "var _b = 10");
+  yield refreshPanel(panel);
 
   // Verify that the variable is displayed now.
   let row = getRowByLabel(panel, "_b");
diff --git a/devtools/client/dom/test/head.js b/devtools/client/dom/test/head.js
index b5de0f09cb44..781441b065d4 100644
--- a/devtools/client/dom/test/head.js
+++ b/devtools/client/dom/test/head.js
@@ -225,12 +225,12 @@ function waitForDispatch(panel, type, eventRepeat = 1) {
   const actionType = constants[type];
   let count = 0;
 
-  return (async function () {
+  return Task.spawn(function* () {
     info("Waiting for " + type + " to dispatch " + eventRepeat + " time(s)");
     while (count < eventRepeat) {
-      await _afterDispatchDone(store, actionType);
+      yield _afterDispatchDone(store, actionType);
       count++;
       info(type + " dispatched " + count + " time(s)");
     }
-  })();
+  });
 }
diff --git a/devtools/client/framework/connect/connect.js b/devtools/client/framework/connect/connect.js
index debb4dc4be48..81389772ccb9 100644
--- a/devtools/client/framework/connect/connect.js
+++ b/devtools/client/framework/connect/connect.js
@@ -12,6 +12,7 @@ var {gDevTools} = require("devtools/client/framework/devtools");
 var {TargetFactory} = require("devtools/client/framework/target");
 var {Toolbox} = require("devtools/client/framework/toolbox");
 var {DebuggerClient} = require("devtools/shared/client/debugger-client");
+var {Task} = require("devtools/shared/task");
 var {LocalizationHelper} = require("devtools/shared/l10n");
 var L10N = new LocalizationHelper("devtools/client/locales/connection-screen.properties");
 
@@ -47,7 +48,7 @@ window.addEventListener("DOMContentLoaded", function () {
 /**
  * Called when the "connect" button is clicked.
  */
-var submit = async function () {
+var submit = Task.async(function* () {
   // Show the "connecting" screen
   document.body.classList.add("connecting");
 
@@ -63,23 +64,23 @@ var submit = async function () {
   }
 
   // Initiate the connection
-  let transport = await DebuggerClient.socketConnect({ host, port });
+  let transport = yield DebuggerClient.socketConnect({ host, port });
   gClient = new DebuggerClient(transport);
   let delay = Services.prefs.getIntPref("devtools.debugger.remote-timeout");
   gConnectionTimeout = setTimeout(handleConnectionTimeout, delay);
-  let response = await gClient.connect();
-  await onConnectionReady(...response);
-};
+  let response = yield gClient.connect();
+  yield onConnectionReady(...response);
+});
 
 /**
  * Connection is ready. List actors and build buttons.
  */
-var onConnectionReady = async function ([aType, aTraits]) {
+var onConnectionReady = Task.async(function* ([aType, aTraits]) {
   clearTimeout(gConnectionTimeout);
 
   let addons = [];
   try {
-    let response = await gClient.listAddons();
+    let response = yield gClient.listAddons();
     if (!response.error && response.addons.length > 0) {
       addons = response.addons;
     }
@@ -103,7 +104,7 @@ var onConnectionReady = async function ([aType, aTraits]) {
     parent.remove();
   }
 
-  let response = await gClient.listTabs();
+  let response = yield gClient.listTabs();
 
   parent = document.getElementById("tabActors");
 
@@ -155,7 +156,7 @@ var onConnectionReady = async function ([aType, aTraits]) {
   if (firstLink) {
     firstLink.focus();
   }
-};
+});
 
 /**
  * Build one button for an add-on actor.
diff --git a/devtools/client/framework/devtools.js b/devtools/client/framework/devtools.js
index b53c81da0670..f7b38ba45c14 100644
--- a/devtools/client/framework/devtools.js
+++ b/devtools/client/framework/devtools.js
@@ -25,6 +25,7 @@ loader.lazyRequireGetter(this, "WebExtensionInspectedWindowFront",
 const {defaultTools: DefaultTools, defaultThemes: DefaultThemes} =
   require("devtools/client/definitions");
 const EventEmitter = require("devtools/shared/old-event-emitter");
+const {Task} = require("devtools/shared/task");
 const {getTheme, setTheme, addThemeObserver, removeThemeObserver} =
   require("devtools/client/shared/theme");
 
@@ -452,15 +453,15 @@ DevTools.prototype = {
    * @return {Toolbox} toolbox
    *        The toolbox that was opened
    */
-  async showToolbox(target, toolId, hostType, hostOptions, startTime) {
+  showToolbox: Task.async(function* (target, toolId, hostType, hostOptions, startTime) {
     let toolbox = this._toolboxes.get(target);
     if (toolbox) {
       if (hostType != null && toolbox.hostType != hostType) {
-        await toolbox.switchHost(hostType);
+        yield toolbox.switchHost(hostType);
       }
 
       if (toolId != null && toolbox.currentToolId != toolId) {
-        await toolbox.selectTool(toolId);
+        yield toolbox.selectTool(toolId);
       }
 
       toolbox.raise();
@@ -470,11 +471,11 @@ DevTools.prototype = {
       // actually trying to create a new one.
       let promise = this._creatingToolboxes.get(target);
       if (promise) {
-        return promise;
+        return yield promise;
       }
       let toolboxPromise = this.createToolbox(target, toolId, hostType, hostOptions);
       this._creatingToolboxes.set(target, toolboxPromise);
-      toolbox = await toolboxPromise;
+      toolbox = yield toolboxPromise;
       this._creatingToolboxes.delete(target);
 
       if (startTime) {
@@ -483,7 +484,7 @@ DevTools.prototype = {
       this._firstShowToolbox = false;
     }
     return toolbox;
-  },
+  }),
 
   /**
    * Log telemetry related to toolbox opening.
@@ -507,10 +508,10 @@ DevTools.prototype = {
     histogram.add(toolId, delay);
   },
 
-  async createToolbox(target, toolId, hostType, hostOptions) {
+  createToolbox: Task.async(function* (target, toolId, hostType, hostOptions) {
     let manager = new ToolboxHostManager(target, hostType, hostOptions);
 
-    let toolbox = await manager.create(toolId);
+    let toolbox = yield manager.create(toolId);
 
     this._toolboxes.set(target, toolbox);
 
@@ -525,11 +526,11 @@ DevTools.prototype = {
       this.emit("toolbox-destroyed", target);
     });
 
-    await toolbox.open();
+    yield toolbox.open();
     this.emit("toolbox-ready", toolbox);
 
     return toolbox;
-  },
+  }),
 
   /**
    * Return the toolbox for a given target.
@@ -552,17 +553,17 @@ DevTools.prototype = {
    *         associated to the target. true, if the toolbox was successfully
    *         closed.
    */
-  async closeToolbox(target) {
-    let toolbox = await this._creatingToolboxes.get(target);
+  closeToolbox: Task.async(function* (target) {
+    let toolbox = yield this._creatingToolboxes.get(target);
     if (!toolbox) {
       toolbox = this._toolboxes.get(target);
     }
     if (!toolbox) {
       return false;
     }
-    await toolbox.destroy();
+    yield toolbox.destroy();
     return true;
-  },
+  }),
 
   /**
    * Wrapper on TargetFactory.forTab, constructs a Target for the provided tab.
diff --git a/devtools/client/framework/sidebar.js b/devtools/client/framework/sidebar.js
index 4845190c2e9a..140b17c52cbc 100644
--- a/devtools/client/framework/sidebar.js
+++ b/devtools/client/framework/sidebar.js
@@ -5,6 +5,7 @@
 "use strict";
 
 var Services = require("Services");
+var {Task} = require("devtools/shared/task");
 var EventEmitter = require("devtools/shared/event-emitter");
 var Telemetry = require("devtools/client/shared/telemetry");
 
@@ -334,7 +335,7 @@ ToolSidebar.prototype = {
    * @param {String} tabPanelId Optional. If provided, this ID will be used
    * instead of the tabId to retrieve and remove the corresponding <tabpanel>
    */
-  async removeTab(tabId, tabPanelId) {
+  removeTab: Task.async(function* (tabId, tabPanelId) {
     // Remove the tab if it can be found
     let tab = this.getTab(tabId);
     if (!tab) {
@@ -343,7 +344,7 @@ ToolSidebar.prototype = {
 
     let win = this.getWindowForTab(tabId);
     if (win && ("destroy" in win)) {
-      await win.destroy();
+      yield win.destroy();
     }
 
     tab.remove();
@@ -356,7 +357,7 @@ ToolSidebar.prototype = {
 
     this._tabs.delete(tabId);
     this.emit("tab-unregistered", tabId);
-  },
+  }),
 
   /**
    * Show or hide a specific tab.
@@ -548,7 +549,7 @@ ToolSidebar.prototype = {
   /**
    * Clean-up.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     if (this._destroyed) {
       return;
     }
@@ -569,7 +570,7 @@ ToolSidebar.prototype = {
       let panel = this._tabbox.tabpanels.firstChild;
       let win = panel.firstChild.contentWindow;
       if (win && ("destroy" in win)) {
-        await win.destroy();
+        yield win.destroy();
       }
       panel.remove();
     }
@@ -588,5 +589,5 @@ ToolSidebar.prototype = {
     this._tabbox = null;
     this._panelDoc = null;
     this._toolPanel = null;
-  }
+  })
 };
diff --git a/devtools/client/framework/test/browser_browser_toolbox.js b/devtools/client/framework/test/browser_browser_toolbox.js
index ade5623abeb9..03988dd40638 100644
--- a/devtools/client/framework/test/browser_browser_toolbox.js
+++ b/devtools/client/framework/test/browser_browser_toolbox.js
@@ -10,7 +10,7 @@ PromiseTestUtils.whitelistRejectionsGlobally(/File closed/);
 // On debug test slave, it takes about 50s to run the test.
 requestLongerTimeout(4);
 
-add_task(async function () {
+add_task(async function() {
   await new Promise(done => {
     let options = {"set": [
       ["devtools.debugger.prompt-connection", false],
diff --git a/devtools/client/framework/test/browser_browser_toolbox_debugger.js b/devtools/client/framework/test/browser_browser_toolbox_debugger.js
index ee0a572aa55d..4fb349377e1e 100644
--- a/devtools/client/framework/test/browser_browser_toolbox_debugger.js
+++ b/devtools/client/framework/test/browser_browser_toolbox_debugger.js
@@ -20,8 +20,8 @@ const { fetch } = require("devtools/shared/DevToolsUtils");
 const debuggerHeadURL = CHROME_URL_ROOT + "../../debugger/new/test/mochitest/head.js";
 const testScriptURL = CHROME_URL_ROOT + "test_browser_toolbox_debugger.js";
 
-add_task(async function runTest() {
-  await new Promise(done => {
+add_task(function* runTest() {
+  yield new Promise(done => {
     let options = {"set": [
       ["devtools.debugger.prompt-connection", false],
       ["devtools.debugger.remote-enabled", true],
@@ -96,6 +96,7 @@ add_task(async function runTest() {
 
     const registerCleanupFunction = () => {};
 
+    const { Task } = ChromeUtils.import("resource://gre/modules/Task.jsm", {});
     const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
     const { Services } = ChromeUtils.import("resource://gre/modules/Services.jsm", {});
 
@@ -118,7 +119,7 @@ add_task(async function runTest() {
   // to ensure inner symbols gets exposed to next pieces of code
 
   // Then inject new debugger head file
-  let { content } = await fetch(debuggerHeadURL);
+  let { content } = yield fetch(debuggerHeadURL);
   let debuggerHead = content;
   // We remove its import of shared-head, which isn't available in browser toolbox process
   // And isn't needed thanks to testHead's symbols
@@ -126,7 +127,7 @@ add_task(async function runTest() {
 
   // Finally, fetch the debugger test script that is going to be execute in the browser
   // toolbox process
-  let testScript = (await fetch(testScriptURL)).content;
+  let testScript = (yield fetch(testScriptURL)).content;
   let source =
     "try { let testUrl = \""+testUrl+"\";" + testHead + debuggerHead + testScript + "} catch (e) {" +
     "  dump('Exception: '+ e + ' at ' + e.fileName + ':' + " +
@@ -141,7 +142,7 @@ add_task(async function runTest() {
   // Use two promises, one for each BrowserToolboxProcess.init callback
   // arguments, to ensure that we wait for toolbox run and close events.
   let closePromise;
-  await new Promise(onRun => {
+  yield new Promise(onRun => {
     closePromise = new Promise(onClose => {
       info("Opening the browser toolbox\n");
       BrowserToolboxProcess.init(onClose, onRun);
@@ -149,7 +150,7 @@ add_task(async function runTest() {
   });
   ok(true, "Browser toolbox started\n");
 
-  await closePromise;
+  yield closePromise;
   ok(true, "Browser toolbox process just closed");
 
   clearInterval(interval);
diff --git a/devtools/client/framework/test/browser_devtools_api.js b/devtools/client/framework/test/browser_devtools_api.js
index 10076234a6b0..8f35931f755c 100644
--- a/devtools/client/framework/test/browser_devtools_api.js
+++ b/devtools/client/framework/test/browser_devtools_api.js
@@ -139,7 +139,7 @@ function runTests2() {
   });
 }
 
-var continueTests = async function (toolbox, panel) {
+var continueTests = Task.async(function* (toolbox, panel) {
   ok(toolbox.getCurrentPanel(), "panel value is correct");
   is(toolbox.currentToolId, toolId2, "toolbox _currentToolId is correct");
 
@@ -151,11 +151,11 @@ var continueTests = async function (toolbox, panel) {
 
   info("Testing toolbox tool-unregistered event");
   let toolSelected = toolbox.once("select");
-  let unregisteredTool = await new Promise(resolve => {
+  let unregisteredTool = yield new Promise(resolve => {
     toolbox.once("tool-unregistered", (e, id) => resolve(id));
     gDevTools.unregisterTool(toolId2);
   });
-  await toolSelected;
+  yield toolSelected;
 
   is(unregisteredTool, toolId2, "Event returns correct id");
   ok(!toolbox.isToolRegistered(toolId2),
@@ -164,7 +164,7 @@ var continueTests = async function (toolbox, panel) {
     "The tool is no longer registered");
 
   info("Testing toolbox tool-registered event");
-  let registeredTool = await new Promise(resolve => {
+  let registeredTool = yield new Promise(resolve => {
     toolbox.once("tool-registered", (e, id) => resolve(id));
     gDevTools.registerTool(toolDefinition);
   });
@@ -180,7 +180,7 @@ var continueTests = async function (toolbox, panel) {
 
   info("Destroying toolbox");
   destroyToolbox(toolbox);
-};
+});
 
 function destroyToolbox(toolbox) {
   toolbox.destroy().then(function () {
diff --git a/devtools/client/framework/test/browser_ignore_toolbox_network_requests.js b/devtools/client/framework/test/browser_ignore_toolbox_network_requests.js
index 300d77622139..b4689ed2070d 100644
--- a/devtools/client/framework/test/browser_ignore_toolbox_network_requests.js
+++ b/devtools/client/framework/test/browser_ignore_toolbox_network_requests.js
@@ -8,26 +8,26 @@
 // Test that network requests originating from the toolbox don't get recorded in
 // the network panel.
 
-add_task(async function () {
+add_task(function* () {
   // TODO: This test tries to verify the normal behavior of the netmonitor and
   // therefore needs to avoid the explicit check for tests. Bug 1167188 will
   // allow us to remove this workaround.
   let isTesting = flags.testing;
   flags.testing = false;
 
-  let tab = await addTab(URL_ROOT + "doc_viewsource.html");
+  let tab = yield addTab(URL_ROOT + "doc_viewsource.html");
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "styleeditor");
+  let toolbox = yield gDevTools.showToolbox(target, "styleeditor");
   let panel = toolbox.getPanel("styleeditor");
 
   is(panel.UI.editors.length, 1, "correct number of editors opened");
 
-  let monitor = await toolbox.selectTool("netmonitor");
+  let monitor = yield toolbox.selectTool("netmonitor");
   let { store, windowRequire } = monitor.panelWin;
 
   is(store.getState().requests.requests.size, 0, "No network requests appear in the network panel");
 
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   tab = target = toolbox = panel = null;
   gBrowser.removeCurrentTab();
   flags.testing = isTesting;
diff --git a/devtools/client/framework/test/browser_keybindings_02.js b/devtools/client/framework/test/browser_keybindings_02.js
index 6d4efd4a379f..551fef8732a2 100644
--- a/devtools/client/framework/test/browser_keybindings_02.js
+++ b/devtools/client/framework/test/browser_keybindings_02.js
@@ -18,24 +18,24 @@ function getZoomValue() {
   return parseFloat(Services.prefs.getCharPref("devtools.toolbox.zoomValue"));
 }
 
-add_task(async function () {
+add_task(function* () {
   info("Create a test tab and open the toolbox");
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "webconsole");
+  let toolbox = yield gDevTools.showToolbox(target, "webconsole");
 
   let {SIDE, BOTTOM} = Toolbox.HostType;
   for (let type of [SIDE, BOTTOM, SIDE]) {
     info("Switch to host type " + type);
-    await toolbox.switchHost(type);
+    yield toolbox.switchHost(type);
 
     info("Try to use the toolbox shortcuts");
-    await checkKeyBindings(toolbox);
+    yield checkKeyBindings(toolbox);
   }
 
   Services.prefs.clearUserPref("devtools.toolbox.zoomValue");
   Services.prefs.setCharPref("devtools.toolbox.host", BOTTOM);
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
 });
 
@@ -51,7 +51,7 @@ function zoomWithKey(toolbox, key) {
   isnot(getZoomValue(), currentZoom, "The zoom level was changed in the toolbox");
 }
 
-function checkKeyBindings(toolbox) {
+function* checkKeyBindings(toolbox) {
   zoomWithKey(toolbox, "toolbox.zoomIn.key");
   zoomWithKey(toolbox, "toolbox.zoomIn2.key");
   zoomWithKey(toolbox, "toolbox.zoomIn3.key");
diff --git a/devtools/client/framework/test/browser_keybindings_03.js b/devtools/client/framework/test/browser_keybindings_03.js
index 29d7cc43df2b..752087a09492 100644
--- a/devtools/client/framework/test/browser_keybindings_03.js
+++ b/devtools/client/framework/test/browser_keybindings_03.js
@@ -15,11 +15,11 @@ var {Toolbox} = require("devtools/client/framework/toolbox");
 const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");
 
-add_task(async function () {
+add_task(function* () {
   info("Create a test tab and open the toolbox");
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "webconsole");
+  let toolbox = yield gDevTools.showToolbox(target, "webconsole");
 
   let shortcut = L10N.getStr("toolbox.toggleHost.key");
 
@@ -29,25 +29,25 @@ add_task(async function () {
   info("Switching from bottom to side");
   let onHostChanged = toolbox.once("host-changed");
   synthesizeKeyShortcut(shortcut, toolbox.win);
-  await onHostChanged;
+  yield onHostChanged;
   checkHostType(toolbox, SIDE, BOTTOM);
 
   info("Switching from side to bottom");
   onHostChanged = toolbox.once("host-changed");
   synthesizeKeyShortcut(shortcut, toolbox.win);
-  await onHostChanged;
+  yield onHostChanged;
   checkHostType(toolbox, BOTTOM, SIDE);
 
   info("Switching to window");
-  await toolbox.switchHost(WINDOW);
+  yield toolbox.switchHost(WINDOW);
   checkHostType(toolbox, WINDOW, BOTTOM);
 
   info("Switching from window to bottom");
   onHostChanged = toolbox.once("host-changed");
   synthesizeKeyShortcut(shortcut, toolbox.win);
-  await onHostChanged;
+  yield onHostChanged;
   checkHostType(toolbox, BOTTOM, WINDOW);
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
 });
diff --git a/devtools/client/framework/test/browser_menu_api.js b/devtools/client/framework/test/browser_menu_api.js
index 9570ff735f7f..5eb52109242c 100644
--- a/devtools/client/framework/test/browser_menu_api.js
+++ b/devtools/client/framework/test/browser_menu_api.js
@@ -11,18 +11,18 @@ const URL = "data:text/html;charset=utf8,test page for menu api";
 const Menu = require("devtools/client/framework/menu");
 const MenuItem = require("devtools/client/framework/menu-item");
 
-add_task(async function () {
+add_task(function* () {
   info("Create a test tab and open the toolbox");
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "webconsole");
+  let toolbox = yield gDevTools.showToolbox(target, "webconsole");
 
-  await testMenuItems();
-  await testMenuPopup(toolbox);
-  await testSubmenu(toolbox);
+  yield testMenuItems();
+  yield testMenuPopup(toolbox);
+  yield testSubmenu(toolbox);
 });
 
-function testMenuItems() {
+function* testMenuItems() {
   let menu = new Menu();
   let menuItem1 = new MenuItem();
   let menuItem2 = new MenuItem();
@@ -35,7 +35,7 @@ function testMenuItems() {
   is(menu.items[1], menuItem2, "Correct reference to MenuItem");
 }
 
-async function testMenuPopup(toolbox) {
+function* testMenuPopup(toolbox) {
   let clickFired = false;
 
   let menu = new Menu({
@@ -102,16 +102,16 @@ async function testMenuPopup(toolbox) {
   is(menuItems[3].getAttribute("label"), MENU_ITEMS[3].label, "Correct label");
   is(menuItems[3].getAttribute("disabled"), "true", "disabled attr menuitem");
 
-  await once(menu, "open");
+  yield once(menu, "open");
   let closed = once(menu, "close");
   EventUtils.synthesizeMouseAtCenter(menuItems[0], {}, toolbox.win);
-  await closed;
+  yield closed;
   ok(clickFired, "Click has fired");
 
   ok(!toolbox.doc.querySelector("#menu-popup"), "Popup removed from the DOM");
 }
 
-async function testSubmenu(toolbox) {
+function* testSubmenu(toolbox) {
   let clickFired = false;
   let menu = new Menu({
     id: "menu-popup",
@@ -156,26 +156,26 @@ async function testSubmenu(toolbox) {
   is(subMenuItems.length, 1, "Correct number of submenu items");
   is(subMenuItems[0].getAttribute("label"), "Submenu item", "Correct label");
 
-  await once(menu, "open");
+  yield once(menu, "open");
   let closed = once(menu, "close");
 
   info("Using keyboard navigation to open, close, and reopen the submenu");
   let shown = once(menus[0], "popupshown");
   EventUtils.synthesizeKey("KEY_ArrowDown");
   EventUtils.synthesizeKey("KEY_ArrowRight");
-  await shown;
+  yield shown;
 
   let hidden = once(menus[0], "popuphidden");
   EventUtils.synthesizeKey("KEY_ArrowLeft");
-  await hidden;
+  yield hidden;
 
   shown = once(menus[0], "popupshown");
   EventUtils.synthesizeKey("KEY_ArrowRight");
-  await shown;
+  yield shown;
 
   info("Clicking the submenu item");
   EventUtils.synthesizeMouseAtCenter(subMenuItems[0], {}, toolbox.win);
 
-  await closed;
+  yield closed;
   ok(clickFired, "Click has fired");
 }
diff --git a/devtools/client/framework/test/browser_source_map-01.js b/devtools/client/framework/test/browser_source_map-01.js
index a4d6ba6461be..0483d336b9fc 100644
--- a/devtools/client/framework/test/browser_source_map-01.js
+++ b/devtools/client/framework/test/browser_source_map-01.js
@@ -20,26 +20,26 @@ const PAGE_URL = `${URL_ROOT}doc_empty-tab-01.html`;
 const JS_URL = `${URL_ROOT}code_binary_search.js`;
 const COFFEE_URL = `${URL_ROOT}code_binary_search.coffee`;
 
-add_task(async function () {
-  await pushPref("devtools.debugger.new-debugger-frontend", true);
+add_task(function* () {
+  yield pushPref("devtools.debugger.new-debugger-frontend", true);
 
-  const toolbox = await openNewTabAndToolbox(PAGE_URL, "jsdebugger");
+  const toolbox = yield openNewTabAndToolbox(PAGE_URL, "jsdebugger");
   const service = toolbox.sourceMapURLService;
 
   // Inject JS script
   let sourceSeen = waitForSourceLoad(toolbox, JS_URL);
-  await createScript(JS_URL);
-  await sourceSeen;
+  yield createScript(JS_URL);
+  yield sourceSeen;
 
   let loc1 = { url: JS_URL, line: 6 };
-  let newLoc1 = await service.originalPositionFor(loc1.url, loc1.line, 4);
+  let newLoc1 = yield service.originalPositionFor(loc1.url, loc1.line, 4);
   checkLoc1(loc1, newLoc1);
 
   let loc2 = { url: JS_URL, line: 8, column: 3 };
-  let newLoc2 = await service.originalPositionFor(loc2.url, loc2.line, loc2.column);
+  let newLoc2 = yield service.originalPositionFor(loc2.url, loc2.line, loc2.column);
   checkLoc2(loc2, newLoc2);
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
   finish();
 });
diff --git a/devtools/client/framework/test/browser_source_map-absolute.js b/devtools/client/framework/test/browser_source_map-absolute.js
index 697371a80a50..000c4f9b4e5f 100644
--- a/devtools/client/framework/test/browser_source_map-absolute.js
+++ b/devtools/client/framework/test/browser_source_map-absolute.js
@@ -15,19 +15,19 @@ const PAGE_URL = `${URL_ROOT}doc_empty-tab-01.html`;
 const JS_URL = `${URL_ROOT}code_binary_search_absolute.js`;
 const ORIGINAL_URL = `${URL_ROOT}code_binary_search.coffee`;
 
-add_task(async function () {
-  await pushPref("devtools.debugger.new-debugger-frontend", true);
+add_task(function* () {
+  yield pushPref("devtools.debugger.new-debugger-frontend", true);
 
-  const toolbox = await openNewTabAndToolbox(PAGE_URL, "jsdebugger");
+  const toolbox = yield openNewTabAndToolbox(PAGE_URL, "jsdebugger");
   const service = toolbox.sourceMapURLService;
 
   // Inject JS script
   let sourceSeen = waitForSourceLoad(toolbox, JS_URL);
-  await createScript(JS_URL);
-  await sourceSeen;
+  yield createScript(JS_URL);
+  yield sourceSeen;
 
   info(`checking original location for ${JS_URL}:6`);
-  let newLoc = await service.originalPositionFor(JS_URL, 6, 4);
+  let newLoc = yield service.originalPositionFor(JS_URL, 6, 4);
 
   is(newLoc.sourceUrl, ORIGINAL_URL, "check mapped URL");
   is(newLoc.line, 4, "check mapped line number");
diff --git a/devtools/client/framework/test/browser_source_map-cross-domain.js b/devtools/client/framework/test/browser_source_map-cross-domain.js
index d2ba21e5e625..5eb82f8859db 100644
--- a/devtools/client/framework/test/browser_source_map-cross-domain.js
+++ b/devtools/client/framework/test/browser_source_map-cross-domain.js
@@ -28,12 +28,12 @@ const ORIGINAL_URL = "webpack:///code_cross_domain.js";
 const GENERATED_LINE = 82;
 const ORIGINAL_LINE = 12;
 
-add_task(async function () {
-  const toolbox = await openNewTabAndToolbox(PAGE_URL, "webconsole");
+add_task(function* () {
+  const toolbox = yield openNewTabAndToolbox(PAGE_URL, "webconsole");
   const service = toolbox.sourceMapURLService;
 
   info(`checking original location for ${JS_URL}:${GENERATED_LINE}`);
-  let newLoc = await service.originalPositionFor(JS_URL, GENERATED_LINE);
+  let newLoc = yield service.originalPositionFor(JS_URL, GENERATED_LINE);
   is(newLoc.sourceUrl, ORIGINAL_URL, "check mapped URL");
   is(newLoc.line, ORIGINAL_LINE, "check mapped line number");
 });
diff --git a/devtools/client/framework/test/browser_source_map-init.js b/devtools/client/framework/test/browser_source_map-init.js
index 5b0d167f83d0..8474faf131f0 100644
--- a/devtools/client/framework/test/browser_source_map-init.js
+++ b/devtools/client/framework/test/browser_source_map-init.js
@@ -28,16 +28,16 @@ const ORIGINAL_URL = "webpack:///code_no_race.js";
 const GENERATED_LINE = 84;
 const ORIGINAL_LINE = 11;
 
-add_task(async function () {
+add_task(function* () {
   // Opening the debugger causes the source actors to be created.
-  const toolbox = await openNewTabAndToolbox(PAGE_URL, "jsdebugger");
+  const toolbox = yield openNewTabAndToolbox(PAGE_URL, "jsdebugger");
   // In bug 1391768, when the sourceMapURLService was created, it was
   // ignoring any source actors that already existed, leading to
   // source-mapping failures for those.
   const service = toolbox.sourceMapURLService;
 
   info(`checking original location for ${JS_URL}:${GENERATED_LINE}`);
-  let newLoc = await service.originalPositionFor(JS_URL, GENERATED_LINE);
+  let newLoc = yield service.originalPositionFor(JS_URL, GENERATED_LINE);
   is(newLoc.sourceUrl, ORIGINAL_URL, "check mapped URL");
   is(newLoc.line, ORIGINAL_LINE, "check mapped line number");
 });
diff --git a/devtools/client/framework/test/browser_source_map-inline.js b/devtools/client/framework/test/browser_source_map-inline.js
index 686bdc467696..fd176d092287 100644
--- a/devtools/client/framework/test/browser_source_map-inline.js
+++ b/devtools/client/framework/test/browser_source_map-inline.js
@@ -17,24 +17,24 @@ const PAGE_URL = `${TEST_ROOT}doc_empty-tab-01.html`;
 const JS_URL = `${TEST_ROOT}code_inline_bundle.js`;
 const ORIGINAL_URL = "webpack:///code_inline_original.js";
 
-add_task(async function () {
-  await pushPref("devtools.debugger.new-debugger-frontend", true);
+add_task(function* () {
+  yield pushPref("devtools.debugger.new-debugger-frontend", true);
 
-  const toolbox = await openNewTabAndToolbox(PAGE_URL, "jsdebugger");
+  const toolbox = yield openNewTabAndToolbox(PAGE_URL, "jsdebugger");
   const service = toolbox.sourceMapURLService;
 
   // Inject JS script
   let sourceSeen = waitForSourceLoad(toolbox, JS_URL);
-  await createScript(JS_URL);
-  await sourceSeen;
+  yield createScript(JS_URL);
+  yield sourceSeen;
 
   info(`checking original location for ${JS_URL}:84`);
-  let newLoc = await service.originalPositionFor(JS_URL, 84);
+  let newLoc = yield service.originalPositionFor(JS_URL, 84);
 
   is(newLoc.sourceUrl, ORIGINAL_URL, "check mapped URL");
   is(newLoc.line, 11, "check mapped line number");
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
   finish();
 });
diff --git a/devtools/client/framework/test/browser_source_map-no-race.js b/devtools/client/framework/test/browser_source_map-no-race.js
index 64b9e2c9a997..d7ed3c6747fc 100644
--- a/devtools/client/framework/test/browser_source_map-no-race.js
+++ b/devtools/client/framework/test/browser_source_map-no-race.js
@@ -28,14 +28,14 @@ const ORIGINAL_URL = "webpack:///code_no_race.js";
 const GENERATED_LINE = 84;
 const ORIGINAL_LINE = 11;
 
-add_task(async function () {
+add_task(function* () {
   // Start with the empty page, then navigate, so that we can properly
   // listen for new sources arriving.
-  const toolbox = await openNewTabAndToolbox(PAGE_URL, "webconsole");
+  const toolbox = yield openNewTabAndToolbox(PAGE_URL, "webconsole");
   const service = toolbox.sourceMapURLService;
 
   info(`checking original location for ${JS_URL}:${GENERATED_LINE}`);
-  let newLoc = await service.originalPositionFor(JS_URL, GENERATED_LINE);
+  let newLoc = yield service.originalPositionFor(JS_URL, GENERATED_LINE);
   is(newLoc.sourceUrl, ORIGINAL_URL, "check mapped URL");
   is(newLoc.line, ORIGINAL_LINE, "check mapped line number");
 });
diff --git a/devtools/client/framework/test/browser_source_map-reload.js b/devtools/client/framework/test/browser_source_map-reload.js
index 4129a45c2535..3819080cbd58 100644
--- a/devtools/client/framework/test/browser_source_map-reload.js
+++ b/devtools/client/framework/test/browser_source_map-reload.js
@@ -15,36 +15,36 @@ const ORIGINAL_URL_2 = "webpack:///code_reload_2.js";
 const GENERATED_LINE = 86;
 const ORIGINAL_LINE = 13;
 
-add_task(async function () {
-  await pushPref("devtools.debugger.new-debugger-frontend", true);
+add_task(function* () {
+  yield pushPref("devtools.debugger.new-debugger-frontend", true);
 
   // Start with the empty page, then navigate, so that we can properly
   // listen for new sources arriving.
-  const toolbox = await openNewTabAndToolbox(INITIAL_URL, "webconsole");
+  const toolbox = yield openNewTabAndToolbox(INITIAL_URL, "webconsole");
   const service = toolbox.sourceMapURLService;
   const tab = toolbox.target.tab;
 
   let sourceSeen = waitForSourceLoad(toolbox, JS_URL);
   tab.linkedBrowser.loadURI(PAGE_URL);
-  await sourceSeen;
+  yield sourceSeen;
 
   info(`checking original location for ${JS_URL}:${GENERATED_LINE}`);
-  let newLoc = await service.originalPositionFor(JS_URL, GENERATED_LINE);
+  let newLoc = yield service.originalPositionFor(JS_URL, GENERATED_LINE);
   is(newLoc.sourceUrl, ORIGINAL_URL_1, "check mapped URL");
   is(newLoc.line, ORIGINAL_LINE, "check mapped line number");
 
   // Reload the page.  The sjs ensures that a different source file
   // will be loaded.
   sourceSeen = waitForSourceLoad(toolbox, JS_URL);
-  await refreshTab();
-  await sourceSeen;
+  yield refreshTab();
+  yield sourceSeen;
 
   info(`checking post-reload original location for ${JS_URL}:${GENERATED_LINE}`);
-  newLoc = await service.originalPositionFor(JS_URL, GENERATED_LINE);
+  newLoc = yield service.originalPositionFor(JS_URL, GENERATED_LINE);
   is(newLoc.sourceUrl, ORIGINAL_URL_2, "check post-reload mapped URL");
   is(newLoc.line, ORIGINAL_LINE, "check post-reload mapped line number");
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
   finish();
 });
diff --git a/devtools/client/framework/test/browser_target_from_url.js b/devtools/client/framework/test/browser_target_from_url.js
index 92972f5612b3..e28e35592a22 100644
--- a/devtools/client/framework/test/browser_target_from_url.js
+++ b/devtools/client/framework/test/browser_target_from_url.js
@@ -23,14 +23,14 @@ function assertIsTabTarget(target, url, chrome = false) {
   is(target.isRemote, true);
 }
 
-add_task(async function () {
-  let tab = await addTab(TEST_URI);
+add_task(function* () {
+  let tab = yield addTab(TEST_URI);
   let browser = tab.linkedBrowser;
   let target;
 
   info("Test invalid type");
   try {
-    await targetFromURL(new URL("http://foo?type=x"));
+    yield targetFromURL(new URL("http://foo?type=x"));
     ok(false, "Shouldn't pass");
   } catch (e) {
     is(e.message, "targetFromURL, unsupported type 'x' parameter");
@@ -40,7 +40,7 @@ add_task(async function () {
   let windowId = window.QueryInterface(Ci.nsIInterfaceRequestor)
                        .getInterface(Ci.nsIDOMWindowUtils)
                        .outerWindowID;
-  target = await targetFromURL(new URL("http://foo?type=window&id=" + windowId));
+  target = yield targetFromURL(new URL("http://foo?type=window&id=" + windowId));
   is(target.url, window.location.href);
   is(target.isLocalTab, false);
   is(target.chrome, true);
@@ -49,33 +49,33 @@ add_task(async function () {
 
   info("Test tab");
   windowId = browser.outerWindowID;
-  target = await targetFromURL(new URL("http://foo?type=tab&id=" + windowId));
+  target = yield targetFromURL(new URL("http://foo?type=tab&id=" + windowId));
   assertIsTabTarget(target, TEST_URI);
 
   info("Test tab with chrome privileges");
-  target = await targetFromURL(new URL("http://foo?type=tab&id=" + windowId + "&chrome"));
+  target = yield targetFromURL(new URL("http://foo?type=tab&id=" + windowId + "&chrome"));
   assertIsTabTarget(target, TEST_URI, true);
 
   info("Test invalid tab id");
   try {
-    await targetFromURL(new URL("http://foo?type=tab&id=10000"));
+    yield targetFromURL(new URL("http://foo?type=tab&id=10000"));
     ok(false, "Shouldn't pass");
   } catch (e) {
     is(e.message, "targetFromURL, tab with outerWindowID '10000' doesn't exist");
   }
 
   info("Test parent process");
-  target = await targetFromURL(new URL("http://foo?type=process"));
+  target = yield targetFromURL(new URL("http://foo?type=process"));
   let topWindow = Services.wm.getMostRecentWindow("navigator:browser");
   assertIsTabTarget(target, topWindow.location.href, true);
 
-  await testRemoteTCP();
-  await testRemoteWebSocket();
+  yield testRemoteTCP();
+  yield testRemoteWebSocket();
 
   gBrowser.removeCurrentTab();
 });
 
-async function setupDebuggerServer(websocket) {
+function* setupDebuggerServer(websocket) {
   info("Create a separate loader instance for the DebuggerServer.");
   let loader = new DevToolsLoader();
   let { DebuggerServer } = loader.require("devtools/server/main");
@@ -89,7 +89,7 @@ async function setupDebuggerServer(websocket) {
   // Pass -1 to automatically choose an available port
   listener.portOrPath = -1;
   listener.webSocket = websocket;
-  await listener.open();
+  yield listener.open();
   is(DebuggerServer.listeningSockets, 1, "1 listening socket");
 
   return { DebuggerServer, listener };
@@ -104,13 +104,13 @@ function teardownDebuggerServer({ DebuggerServer, listener }) {
   DebuggerServer.destroy();
 }
 
-async function testRemoteTCP() {
+function* testRemoteTCP() {
   info("Test remote process via TCP Connection");
 
-  let server = await setupDebuggerServer(false);
+  let server = yield setupDebuggerServer(false);
 
   let { port } = server.listener;
-  let target = await targetFromURL(new URL("http://foo?type=process&host=127.0.0.1&port=" + port));
+  let target = yield targetFromURL(new URL("http://foo?type=process&host=127.0.0.1&port=" + port));
   let topWindow = Services.wm.getMostRecentWindow("navigator:browser");
   assertIsTabTarget(target, topWindow.location.href, true);
 
@@ -119,18 +119,18 @@ async function testRemoteTCP() {
   is(settings.port, port);
   is(settings.webSocket, false);
 
-  await target.client.close();
+  yield target.client.close();
 
   teardownDebuggerServer(server);
 }
 
-async function testRemoteWebSocket() {
+function* testRemoteWebSocket() {
   info("Test remote process via WebSocket Connection");
 
-  let server = await setupDebuggerServer(true);
+  let server = yield setupDebuggerServer(true);
 
   let { port } = server.listener;
-  let target = await targetFromURL(new URL("http://foo?type=process&host=127.0.0.1&port=" + port + "&ws=true"));
+  let target = yield targetFromURL(new URL("http://foo?type=process&host=127.0.0.1&port=" + port + "&ws=true"));
   let topWindow = Services.wm.getMostRecentWindow("navigator:browser");
   assertIsTabTarget(target, topWindow.location.href, true);
 
@@ -138,7 +138,7 @@ async function testRemoteWebSocket() {
   is(settings.host, "127.0.0.1");
   is(settings.port, port);
   is(settings.webSocket, true);
-  await target.client.close();
+  yield target.client.close();
 
   teardownDebuggerServer(server);
 }
diff --git a/devtools/client/framework/test/browser_target_support.js b/devtools/client/framework/test/browser_target_support.js
index c69bb8f40532..0cdbd565ab7d 100644
--- a/devtools/client/framework/test/browser_target_support.js
+++ b/devtools/client/framework/test/browser_target_support.js
@@ -9,8 +9,8 @@
 var { WebAudioFront } =
   require("devtools/shared/fronts/webaudio");
 
-async function testTarget(client, target) {
-  await target.makeRemote();
+function* testTarget(client, target) {
+  yield target.makeRemote();
 
   is(target.hasActor("timeline"), true, "target.hasActor() true when actor exists.");
   is(target.hasActor("webaudio"), true, "target.hasActor() true when actor exists.");
@@ -18,27 +18,27 @@ async function testTarget(client, target) {
   // Create a front to ensure the actor is loaded
   let front = new WebAudioFront(target.client, target.form);
 
-  let desc = await target.getActorDescription("webaudio");
+  let desc = yield target.getActorDescription("webaudio");
   is(desc.typeName, "webaudio",
     "target.getActorDescription() returns definition data for corresponding actor");
   is(desc.events["start-context"]["type"], "startContext",
     "target.getActorDescription() returns event data for corresponding actor");
 
-  desc = await target.getActorDescription("nope");
+  desc = yield target.getActorDescription("nope");
   is(desc, undefined, "target.getActorDescription() returns undefined for non-existing actor");
-  desc = await target.getActorDescription();
+  desc = yield target.getActorDescription();
   is(desc, undefined, "target.getActorDescription() returns undefined for undefined actor");
 
-  let hasMethod = await target.actorHasMethod("audionode", "getType");
+  let hasMethod = yield target.actorHasMethod("audionode", "getType");
   is(hasMethod, true,
     "target.actorHasMethod() returns true for existing actor with method");
-  hasMethod = await target.actorHasMethod("audionode", "nope");
+  hasMethod = yield target.actorHasMethod("audionode", "nope");
   is(hasMethod, false,
     "target.actorHasMethod() returns false for existing actor with no method");
-  hasMethod = await target.actorHasMethod("nope", "nope");
+  hasMethod = yield target.actorHasMethod("nope", "nope");
   is(hasMethod, false,
     "target.actorHasMethod() returns false for non-existing actor with no method");
-  hasMethod = await target.actorHasMethod();
+  hasMethod = yield target.actorHasMethod();
   is(hasMethod, false,
     "target.actorHasMethod() returns false for undefined params");
 
diff --git a/devtools/client/framework/test/browser_toolbox_getpanelwhenready.js b/devtools/client/framework/test/browser_toolbox_getpanelwhenready.js
index 29047ab628ee..21dd236a1971 100644
--- a/devtools/client/framework/test/browser_toolbox_getpanelwhenready.js
+++ b/devtools/client/framework/test/browser_toolbox_getpanelwhenready.js
@@ -10,27 +10,27 @@ var toolbox = null;
 
 const URL = "data:text/html;charset=utf8,test for getPanelWhenReady";
 
-add_task(async function () {
-  let tab = await addTab(URL);
+add_task(function* () {
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  toolbox = await gDevTools.showToolbox(target);
+  toolbox = yield gDevTools.showToolbox(target);
 
   let debuggerPanelPromise = toolbox.getPanelWhenReady("jsdebugger");
-  await toolbox.selectTool("jsdebugger");
-  let debuggerPanel = await debuggerPanelPromise;
+  yield toolbox.selectTool("jsdebugger");
+  let debuggerPanel = yield debuggerPanelPromise;
 
   is(debuggerPanel, toolbox.getPanel("jsdebugger"),
       "The debugger panel from getPanelWhenReady before loading is the actual panel");
 
-  let debuggerPanel2 = await toolbox.getPanelWhenReady("jsdebugger");
+  let debuggerPanel2 = yield toolbox.getPanelWhenReady("jsdebugger");
   is(debuggerPanel2, toolbox.getPanel("jsdebugger"),
       "The debugger panel from getPanelWhenReady after loading is the actual panel");
 
-  await cleanup();
+  yield cleanup();
 });
 
-async function cleanup() {
-  await toolbox.destroy();
+function* cleanup() {
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
   toolbox = null;
 }
diff --git a/devtools/client/framework/test/browser_toolbox_highlight.js b/devtools/client/framework/test/browser_toolbox_highlight.js
index cd437afdcbcb..085366a429ee 100644
--- a/devtools/client/framework/test/browser_toolbox_highlight.js
+++ b/devtools/client/framework/test/browser_toolbox_highlight.js
@@ -10,49 +10,49 @@ var {Toolbox} = require("devtools/client/framework/toolbox");
 var toolbox = null;
 
 function test() {
-  (async function () {
+  Task.spawn(function* () {
     const URL = "data:text/plain;charset=UTF-8,Nothing to see here, move along";
 
     const TOOL_ID_1 = "jsdebugger";
     const TOOL_ID_2 = "webconsole";
-    await addTab(URL);
+    yield addTab(URL);
 
     const target = TargetFactory.forTab(gBrowser.selectedTab);
-    toolbox = await gDevTools.showToolbox(target, TOOL_ID_1, Toolbox.HostType.BOTTOM);
+    toolbox = yield gDevTools.showToolbox(target, TOOL_ID_1, Toolbox.HostType.BOTTOM);
 
     // select tool 2
-    await toolbox.selectTool(TOOL_ID_2);
+    yield toolbox.selectTool(TOOL_ID_2);
     // and highlight the first one
-    await highlightTab(TOOL_ID_1);
+    yield highlightTab(TOOL_ID_1);
     // to see if it has the proper class.
-    await checkHighlighted(TOOL_ID_1);
+    yield checkHighlighted(TOOL_ID_1);
     // Now switch back to first tool
-    await toolbox.selectTool(TOOL_ID_1);
+    yield toolbox.selectTool(TOOL_ID_1);
     // to check again. But there is no easy way to test if
     // it is showing orange or not.
-    await checkNoHighlightWhenSelected(TOOL_ID_1);
+    yield checkNoHighlightWhenSelected(TOOL_ID_1);
     // Switch to tool 2 again
-    await toolbox.selectTool(TOOL_ID_2);
+    yield toolbox.selectTool(TOOL_ID_2);
     // and check again.
-    await checkHighlighted(TOOL_ID_1);
+    yield checkHighlighted(TOOL_ID_1);
     // Highlight another tool
-    await highlightTab(TOOL_ID_2);
+    yield highlightTab(TOOL_ID_2);
     // Check that both tools are highlighted.
-    await checkHighlighted(TOOL_ID_1);
+    yield checkHighlighted(TOOL_ID_1);
     // Check second tool being both highlighted and selected.
-    await checkNoHighlightWhenSelected(TOOL_ID_2);
+    yield checkNoHighlightWhenSelected(TOOL_ID_2);
     // Select tool 1
-    await toolbox.selectTool(TOOL_ID_1);
+    yield toolbox.selectTool(TOOL_ID_1);
     // Check second tool is still highlighted
-    await checkHighlighted(TOOL_ID_2);
+    yield checkHighlighted(TOOL_ID_2);
     // Unhighlight the second tool
-    await unhighlightTab(TOOL_ID_2);
+    yield unhighlightTab(TOOL_ID_2);
     // to see the classes gone.
-    await checkNoHighlight(TOOL_ID_2);
+    yield checkNoHighlight(TOOL_ID_2);
     // Now unhighlight the tool
-    await unhighlightTab(TOOL_ID_1);
+    yield unhighlightTab(TOOL_ID_1);
     // to see the classes gone.
-    await checkNoHighlight(TOOL_ID_1);
+    yield checkNoHighlight(TOOL_ID_1);
 
     // Now close the toolbox and exit.
     executeSoon(() => {
@@ -62,7 +62,7 @@ function test() {
         finish();
       });
     });
-  })()
+  })
   .catch(error => {
     ok(false, "There was an error running the test.");
   });
diff --git a/devtools/client/framework/test/browser_toolbox_hosts.js b/devtools/client/framework/test/browser_toolbox_hosts.js
index 5f5ee757971a..adb0512a6af0 100644
--- a/devtools/client/framework/test/browser_toolbox_hosts.js
+++ b/devtools/client/framework/test/browser_toolbox_hosts.js
@@ -11,27 +11,27 @@ var toolbox, target;
 
 const URL = "data:text/html;charset=utf8,test for opening toolbox in different hosts";
 
-add_task(async function runTest() {
+add_task(function* runTest() {
   info("Create a test tab and open the toolbox");
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   target = TargetFactory.forTab(tab);
-  toolbox = await gDevTools.showToolbox(target, "webconsole");
+  toolbox = yield gDevTools.showToolbox(target, "webconsole");
 
-  await testBottomHost();
-  await testSidebarHost();
-  await testWindowHost();
-  await testToolSelect();
-  await testDestroy();
-  await testRememberHost();
-  await testPreviousHost();
+  yield testBottomHost();
+  yield testSidebarHost();
+  yield testWindowHost();
+  yield testToolSelect();
+  yield testDestroy();
+  yield testRememberHost();
+  yield testPreviousHost();
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
 
   toolbox = target = null;
   gBrowser.removeCurrentTab();
 });
 
-function testBottomHost() {
+function* testBottomHost() {
   checkHostType(toolbox, BOTTOM);
 
   // test UI presence
@@ -42,8 +42,8 @@ function testBottomHost() {
   checkToolboxLoaded(iframe);
 }
 
-async function testSidebarHost() {
-  await toolbox.switchHost(SIDE);
+function* testSidebarHost() {
+  yield toolbox.switchHost(SIDE);
   checkHostType(toolbox, SIDE);
 
   // test UI presence
@@ -57,8 +57,8 @@ async function testSidebarHost() {
   checkToolboxLoaded(iframe);
 }
 
-async function testWindowHost() {
-  await toolbox.switchHost(WINDOW);
+function* testWindowHost() {
+  yield toolbox.switchHost(WINDOW);
   checkHostType(toolbox, WINDOW);
 
   let nbox = gBrowser.getNotificationBox();
@@ -72,18 +72,18 @@ async function testWindowHost() {
   checkToolboxLoaded(iframe);
 }
 
-async function testToolSelect() {
+function* testToolSelect() {
   // make sure we can load a tool after switching hosts
-  await toolbox.selectTool("inspector");
+  yield toolbox.selectTool("inspector");
 }
 
-async function testDestroy() {
-  await toolbox.destroy();
+function* testDestroy() {
+  yield toolbox.destroy();
   target = TargetFactory.forTab(gBrowser.selectedTab);
-  toolbox = await gDevTools.showToolbox(target);
+  toolbox = yield gDevTools.showToolbox(target);
 }
 
-function testRememberHost() {
+function* testRememberHost() {
   // last host was the window - make sure it's the same when re-opening
   is(toolbox.hostType, WINDOW, "host remembered");
 
@@ -91,45 +91,45 @@ function testRememberHost() {
   ok(win, "toolbox separate window exists");
 }
 
-async function testPreviousHost() {
+function* testPreviousHost() {
   // last host was the window - make sure it's the same when re-opening
   is(toolbox.hostType, WINDOW, "host remembered");
 
   info("Switching to side");
-  await toolbox.switchHost(SIDE);
+  yield toolbox.switchHost(SIDE);
   checkHostType(toolbox, SIDE, WINDOW);
 
   info("Switching to bottom");
-  await toolbox.switchHost(BOTTOM);
+  yield toolbox.switchHost(BOTTOM);
   checkHostType(toolbox, BOTTOM, SIDE);
 
   info("Switching from bottom to side");
-  await toolbox.switchToPreviousHost();
+  yield toolbox.switchToPreviousHost();
   checkHostType(toolbox, SIDE, BOTTOM);
 
   info("Switching from side to bottom");
-  await toolbox.switchToPreviousHost();
+  yield toolbox.switchToPreviousHost();
   checkHostType(toolbox, BOTTOM, SIDE);
 
   info("Switching to window");
-  await toolbox.switchHost(WINDOW);
+  yield toolbox.switchHost(WINDOW);
   checkHostType(toolbox, WINDOW, BOTTOM);
 
   info("Switching from window to bottom");
-  await toolbox.switchToPreviousHost();
+  yield toolbox.switchToPreviousHost();
   checkHostType(toolbox, BOTTOM, WINDOW);
 
   info("Forcing the previous host to match the current (bottom)");
   Services.prefs.setCharPref("devtools.toolbox.previousHost", BOTTOM);
 
   info("Switching from bottom to side (since previous=current=bottom");
-  await toolbox.switchToPreviousHost();
+  yield toolbox.switchToPreviousHost();
   checkHostType(toolbox, SIDE, BOTTOM);
 
   info("Forcing the previous host to match the current (side)");
   Services.prefs.setCharPref("devtools.toolbox.previousHost", SIDE);
   info("Switching from side to bottom (since previous=current=side");
-  await toolbox.switchToPreviousHost();
+  yield toolbox.switchToPreviousHost();
   checkHostType(toolbox, BOTTOM, SIDE);
 }
 
diff --git a/devtools/client/framework/test/browser_toolbox_hosts_size.js b/devtools/client/framework/test/browser_toolbox_hosts_size.js
index d0167878d46d..4286fe43819b 100644
--- a/devtools/client/framework/test/browser_toolbox_hosts_size.js
+++ b/devtools/client/framework/test/browser_toolbox_hosts_size.js
@@ -10,16 +10,16 @@ const URL = "data:text/html;charset=utf8,test for host sizes";
 
 var {Toolbox} = require("devtools/client/framework/toolbox");
 
-add_task(async function () {
+add_task(function* () {
   // Set size prefs to make the hosts way too big, so that the size has
   // to be clamped to fit into the browser window.
   Services.prefs.setIntPref("devtools.toolbox.footer.height", 10000);
   Services.prefs.setIntPref("devtools.toolbox.sidebar.width", 10000);
 
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let nbox = gBrowser.getNotificationBox();
   let {clientHeight: nboxHeight, clientWidth: nboxWidth} = nbox;
-  let toolbox = await gDevTools.showToolbox(TargetFactory.forTab(tab));
+  let toolbox = yield gDevTools.showToolbox(TargetFactory.forTab(tab));
 
   is(nbox.clientHeight, nboxHeight, "Opening the toolbox hasn't changed the height of the nbox");
   is(nbox.clientWidth, nboxWidth, "Opening the toolbox hasn't changed the width of the nbox");
@@ -27,24 +27,24 @@ add_task(async function () {
   let iframe = document.getAnonymousElementByAttribute(nbox, "class", "devtools-toolbox-bottom-iframe");
   is(iframe.clientHeight, nboxHeight - 25, "The iframe fits within the available space");
 
-  await toolbox.switchHost(Toolbox.HostType.SIDE);
+  yield toolbox.switchHost(Toolbox.HostType.SIDE);
   iframe = document.getAnonymousElementByAttribute(nbox, "class", "devtools-toolbox-side-iframe");
   iframe.style.minWidth = "1px"; // Disable the min width set in css
   is(iframe.clientWidth, nboxWidth - 25, "The iframe fits within the available space");
 
-  await cleanup(toolbox);
+  yield cleanup(toolbox);
 });
 
-add_task(async function () {
+add_task(function* () {
   // Set size prefs to something reasonable, so we can check to make sure
   // they are being set properly.
   Services.prefs.setIntPref("devtools.toolbox.footer.height", 100);
   Services.prefs.setIntPref("devtools.toolbox.sidebar.width", 100);
 
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let nbox = gBrowser.getNotificationBox();
   let {clientHeight: nboxHeight, clientWidth: nboxWidth} = nbox;
-  let toolbox = await gDevTools.showToolbox(TargetFactory.forTab(tab));
+  let toolbox = yield gDevTools.showToolbox(TargetFactory.forTab(tab));
 
   is(nbox.clientHeight, nboxHeight, "Opening the toolbox hasn't changed the height of the nbox");
   is(nbox.clientWidth, nboxWidth, "Opening the toolbox hasn't changed the width of the nbox");
@@ -52,18 +52,18 @@ add_task(async function () {
   let iframe = document.getAnonymousElementByAttribute(nbox, "class", "devtools-toolbox-bottom-iframe");
   is(iframe.clientHeight, 100, "The iframe is resized properly");
 
-  await toolbox.switchHost(Toolbox.HostType.SIDE);
+  yield toolbox.switchHost(Toolbox.HostType.SIDE);
   iframe = document.getAnonymousElementByAttribute(nbox, "class", "devtools-toolbox-side-iframe");
   iframe.style.minWidth = "1px"; // Disable the min width set in css
   is(iframe.clientWidth, 100, "The iframe is resized properly");
 
-  await cleanup(toolbox);
+  yield cleanup(toolbox);
 });
 
-async function cleanup(toolbox) {
+function* cleanup(toolbox) {
   Services.prefs.clearUserPref("devtools.toolbox.host");
   Services.prefs.clearUserPref("devtools.toolbox.footer.height");
   Services.prefs.clearUserPref("devtools.toolbox.sidebar.width");
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
 }
diff --git a/devtools/client/framework/test/browser_toolbox_hosts_telemetry.js b/devtools/client/framework/test/browser_toolbox_hosts_telemetry.js
index 3a8c23c1ea30..f8ff9b3e417e 100644
--- a/devtools/client/framework/test/browser_toolbox_hosts_telemetry.js
+++ b/devtools/client/framework/test/browser_toolbox_hosts_telemetry.js
@@ -12,18 +12,18 @@ function getHostHistogram() {
   return Services.telemetry.getHistogramById("DEVTOOLS_TOOLBOX_HOST");
 }
 
-add_task(async function () {
+add_task(function* () {
   // Reset it to make counting easier
   getHostHistogram().clear();
 
   info("Create a test tab and open the toolbox");
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "webconsole");
+  let toolbox = yield gDevTools.showToolbox(target, "webconsole");
 
-  await changeToolboxHost(toolbox);
-  await checkResults();
-  await toolbox.destroy();
+  yield changeToolboxHost(toolbox);
+  yield checkResults();
+  yield toolbox.destroy();
 
   toolbox = target = null;
   gBrowser.removeCurrentTab();
@@ -32,14 +32,14 @@ add_task(async function () {
   getHostHistogram().clear();
 });
 
-async function changeToolboxHost(toolbox) {
+function* changeToolboxHost(toolbox) {
   info("Switch toolbox host");
-  await toolbox.switchHost(SIDE);
-  await toolbox.switchHost(WINDOW);
-  await toolbox.switchHost(BOTTOM);
-  await toolbox.switchHost(SIDE);
-  await toolbox.switchHost(WINDOW);
-  await toolbox.switchHost(BOTTOM);
+  yield toolbox.switchHost(SIDE);
+  yield toolbox.switchHost(WINDOW);
+  yield toolbox.switchHost(BOTTOM);
+  yield toolbox.switchHost(SIDE);
+  yield toolbox.switchHost(WINDOW);
+  yield toolbox.switchHost(BOTTOM);
 }
 
 function checkResults() {
diff --git a/devtools/client/framework/test/browser_toolbox_keyboard_navigation.js b/devtools/client/framework/test/browser_toolbox_keyboard_navigation.js
index 7ee9a7ea8307..94eac68225eb 100644
--- a/devtools/client/framework/test/browser_toolbox_keyboard_navigation.js
+++ b/devtools/client/framework/test/browser_toolbox_keyboard_navigation.js
@@ -19,9 +19,9 @@ function containsFocus(aDoc, aElm) {
   return false;
 }
 
-add_task(async function () {
+add_task(function* () {
   info("Create a test tab and open the toolbox");
-  let toolbox = await openNewTabAndToolbox(TEST_URL, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URL, "webconsole");
   let doc = toolbox.doc;
 
   let toolbar = doc.querySelector(".devtools-tabbar");
diff --git a/devtools/client/framework/test/browser_toolbox_minimize.js b/devtools/client/framework/test/browser_toolbox_minimize.js
index 80a8d2607534..9b512632038b 100644
--- a/devtools/client/framework/test/browser_toolbox_minimize.js
+++ b/devtools/client/framework/test/browser_toolbox_minimize.js
@@ -14,93 +14,93 @@
 const URL = "data:text/html;charset=utf8,test page";
 const {Toolbox} = require("devtools/client/framework/toolbox");
 
-add_task(async function () {
+add_task(function* () {
   info("Create a test tab and open the toolbox");
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "webconsole");
+  let toolbox = yield gDevTools.showToolbox(target, "webconsole");
 
   let button = toolbox.doc.querySelector("#toolbox-dock-bottom-minimize");
   ok(button, "The minimize button exists in the default bottom host");
 
   info("Try to minimize the toolbox");
-  await minimize(toolbox);
+  yield minimize(toolbox);
   ok(parseInt(toolbox._host.frame.style.marginBottom, 10) < 0,
      "The toolbox host has been hidden away with a negative-margin");
 
   info("Try to maximize again the toolbox");
-  await maximize(toolbox);
+  yield maximize(toolbox);
   ok(parseInt(toolbox._host.frame.style.marginBottom, 10) == 0,
      "The toolbox host is shown again");
 
   info("Try to minimize again using the keyboard shortcut");
-  await minimizeWithShortcut(toolbox);
+  yield minimizeWithShortcut(toolbox);
   ok(parseInt(toolbox._host.frame.style.marginBottom, 10) < 0,
      "The toolbox host has been hidden away with a negative-margin");
 
   info("Try to maximize again using the keyboard shortcut");
-  await maximizeWithShortcut(toolbox);
+  yield maximizeWithShortcut(toolbox);
   ok(parseInt(toolbox._host.frame.style.marginBottom, 10) == 0,
      "The toolbox host is shown again");
 
   info("Minimize again and switch to another tool");
-  await minimize(toolbox);
+  yield minimize(toolbox);
   let onMaximized = toolbox._host.once("maximized");
-  await toolbox.selectTool("inspector");
-  await onMaximized;
+  yield toolbox.selectTool("inspector");
+  yield onMaximized;
 
   info("Minimize again and click on the tab of the current tool");
-  await minimize(toolbox);
+  yield minimize(toolbox);
   onMaximized = toolbox._host.once("maximized");
   let tabButton = toolbox.doc.querySelector("#toolbox-tab-inspector");
   EventUtils.synthesizeMouseAtCenter(tabButton, {}, toolbox.win);
-  await onMaximized;
+  yield onMaximized;
 
   info("Minimize again and click on the settings tab");
-  await minimize(toolbox);
+  yield minimize(toolbox);
   onMaximized = toolbox._host.once("maximized");
   let settingsButton = toolbox.doc.querySelector("#toolbox-tab-options");
   EventUtils.synthesizeMouseAtCenter(settingsButton, {}, toolbox.win);
-  await onMaximized;
+  yield onMaximized;
 
   info("Switch to a different host");
-  await toolbox.switchHost(Toolbox.HostType.SIDE);
+  yield toolbox.switchHost(Toolbox.HostType.SIDE);
   button = toolbox.doc.querySelector("#toolbox-dock-bottom-minimize");
   ok(!button, "The minimize button doesn't exist in the side host");
 
   Services.prefs.clearUserPref("devtools.toolbox.host");
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
 });
 
-async function minimize(toolbox) {
+function* minimize(toolbox) {
   let button = toolbox.doc.querySelector("#toolbox-dock-bottom-minimize");
   let onMinimized = toolbox._host.once("minimized");
   EventUtils.synthesizeMouseAtCenter(button, {}, toolbox.win);
-  await onMinimized;
+  yield onMinimized;
 }
 
-async function minimizeWithShortcut(toolbox) {
+function* minimizeWithShortcut(toolbox) {
   let key = toolbox.doc.getElementById("toolbox-minimize-key")
                        .getAttribute("key");
   let onMinimized = toolbox._host.once("minimized");
   EventUtils.synthesizeKey(key, {accelKey: true, shiftKey: true},
                            toolbox.win);
-  await onMinimized;
+  yield onMinimized;
 }
 
-async function maximize(toolbox) {
+function* maximize(toolbox) {
   let button = toolbox.doc.querySelector("#toolbox-dock-bottom-minimize");
   let onMaximized = toolbox._host.once("maximized");
   EventUtils.synthesizeMouseAtCenter(button, {}, toolbox.win);
-  await onMaximized;
+  yield onMaximized;
 }
 
-async function maximizeWithShortcut(toolbox) {
+function* maximizeWithShortcut(toolbox) {
   let key = toolbox.doc.getElementById("toolbox-minimize-key")
                        .getAttribute("key");
   let onMaximized = toolbox._host.once("maximized");
   EventUtils.synthesizeKey(key, {accelKey: true, shiftKey: true},
                            toolbox.win);
-  await onMaximized;
+  yield onMaximized;
 }
diff --git a/devtools/client/framework/test/browser_toolbox_options.js b/devtools/client/framework/test/browser_toolbox_options.js
index 60189c18f9cd..6836278da33c 100644
--- a/devtools/client/framework/test/browser_toolbox_options.js
+++ b/devtools/client/framework/test/browser_toolbox_options.js
@@ -14,20 +14,20 @@ const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");
 const {PrefObserver} = require("devtools/client/shared/prefs");
 
-add_task(async function () {
+add_task(function* () {
   const URL = "data:text/html;charset=utf8,test for dynamically registering " +
               "and unregistering tools";
   registerNewTool();
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  toolbox = await gDevTools.showToolbox(target);
+  toolbox = yield gDevTools.showToolbox(target);
   doc = toolbox.doc;
-  await registerNewPerToolboxTool();
-  await testSelectTool();
-  await testOptionsShortcut();
-  await testOptions();
-  await testToggleTools();
-  await cleanup();
+  yield registerNewPerToolboxTool();
+  yield testSelectTool();
+  yield testOptionsShortcut();
+  yield testOptions();
+  yield testToggleTools();
+  yield cleanup();
 });
 
 function registerNewTool() {
@@ -73,26 +73,26 @@ function registerNewPerToolboxTool() {
      "The per-toolbox tool has been registered to the toolbox");
 }
 
-async function testSelectTool() {
+function* testSelectTool() {
   info("Checking to make sure that the options panel can be selected.");
 
   let onceSelected = toolbox.once("options-selected");
   toolbox.selectTool("options");
-  await onceSelected;
+  yield onceSelected;
   ok(true, "Toolbox selected via selectTool method");
 }
 
-async function testOptionsShortcut() {
+function* testOptionsShortcut() {
   info("Selecting another tool, then reselecting options panel with keyboard.");
 
-  await toolbox.selectTool("webconsole");
+  yield toolbox.selectTool("webconsole");
   is(toolbox.currentToolId, "webconsole", "webconsole is selected");
   synthesizeKeyShortcut(L10N.getStr("toolbox.options.key"));
   is(toolbox.currentToolId, "options", "Toolbox selected via shortcut key (1)");
   synthesizeKeyShortcut(L10N.getStr("toolbox.options.key"));
   is(toolbox.currentToolId, "webconsole", "webconsole is selected (1)");
 
-  await toolbox.selectTool("webconsole");
+  yield toolbox.selectTool("webconsole");
   is(toolbox.currentToolId, "webconsole", "webconsole is selected");
   synthesizeKeyShortcut(L10N.getStr("toolbox.help.key"));
   is(toolbox.currentToolId, "options", "Toolbox selected via shortcut key (2)");
@@ -102,7 +102,7 @@ async function testOptionsShortcut() {
   is(toolbox.currentToolId, "options", "Toolbox selected via shortcut key (2)");
 }
 
-async function testOptions() {
+function* testOptions() {
   let tool = toolbox.getPanel("options");
   panelWin = tool.panelWin;
   let prefNodes = tool.panelDoc.querySelectorAll(
@@ -118,19 +118,19 @@ async function testOptions() {
     let prefValue = GetPref(node.getAttribute("data-pref"));
 
     // Test clicking the checkbox for each options pref
-    await testMouseClick(node, prefValue);
+    yield testMouseClick(node, prefValue);
 
     // Do again with opposite values to reset prefs
-    await testMouseClick(node, !prefValue);
+    yield testMouseClick(node, !prefValue);
   }
 
   let prefSelects = tool.panelDoc.querySelectorAll("select[data-pref]");
   for (let node of prefSelects) {
-    await testSelect(node);
+    yield testSelect(node);
   }
 }
 
-async function testSelect(select) {
+function* testSelect(select) {
   let pref = select.getAttribute("data-pref");
   let options = Array.from(select.options);
   info("Checking select for: " + pref);
@@ -157,14 +157,14 @@ async function testSelect(select) {
     let changeEvent = new Event("change");
     select.dispatchEvent(changeEvent);
 
-    await deferred.promise;
+    yield deferred.promise;
 
     ok(changeSeen, "Correct pref was changed");
     observer.destroy();
   }
 }
 
-async function testMouseClick(node, prefValue) {
+function* testMouseClick(node, prefValue) {
   let deferred = defer();
 
   let observer = new PrefObserver("devtools.");
@@ -186,13 +186,13 @@ async function testMouseClick(node, prefValue) {
     EventUtils.synthesizeMouseAtCenter(node, {}, panelWin);
   });
 
-  await deferred.promise;
+  yield deferred.promise;
 
   ok(changeSeen, "Correct pref was changed");
   observer.destroy();
 }
 
-async function testToggleTools() {
+function* testToggleTools() {
   let toolNodes = panelWin.document.querySelectorAll(
     "#default-tools-box input[type=checkbox]:not([data-unsupported])," +
     "#additional-tools-box input[type=checkbox]:not([data-unsupported])");
@@ -220,21 +220,21 @@ async function testToggleTools() {
 
   // Toggle each tool
   for (let node of toolNodes) {
-    await toggleTool(node);
+    yield toggleTool(node);
   }
   // Toggle again to reset tool enablement state
   for (let node of toolNodes) {
-    await toggleTool(node);
+    yield toggleTool(node);
   }
 
   // Test that a tool can still be added when no tabs are present:
   // Disable all tools
   for (let node of enabledTools) {
-    await toggleTool(node);
+    yield toggleTool(node);
   }
   // Re-enable the tools which are enabled by default
   for (let node of enabledTools) {
-    await toggleTool(node);
+    yield toggleTool(node);
   }
 
   // Toggle first, middle, and last tools to ensure that toolbox tabs are
@@ -243,15 +243,15 @@ async function testToggleTools() {
   let middleTool = toolNodes[(toolNodes.length / 2) | 0];
   let lastTool = toolNodes[toolNodes.length - 1];
 
-  await toggleTool(firstTool);
-  await toggleTool(firstTool);
-  await toggleTool(middleTool);
-  await toggleTool(middleTool);
-  await toggleTool(lastTool);
-  await toggleTool(lastTool);
+  yield toggleTool(firstTool);
+  yield toggleTool(firstTool);
+  yield toggleTool(middleTool);
+  yield toggleTool(middleTool);
+  yield toggleTool(lastTool);
+  yield toggleTool(lastTool);
 }
 
-async function toggleTool(node) {
+function* toggleTool(node) {
   let deferred = defer();
 
   let toolId = node.getAttribute("id");
@@ -265,7 +265,7 @@ async function toggleTool(node) {
   node.scrollIntoView();
   EventUtils.synthesizeMouseAtCenter(node, {}, panelWin);
 
-  await deferred.promise;
+  yield deferred.promise;
 }
 
 function checkUnregistered(toolId, deferred, event, data) {
@@ -306,9 +306,9 @@ function GetPref(name) {
   }
 }
 
-async function cleanup() {
+function* cleanup() {
   gDevTools.unregisterTool("test-tool");
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
   for (let pref of modifiedPrefs) {
     Services.prefs.clearUserPref(pref);
diff --git a/devtools/client/framework/test/browser_toolbox_options_disable_cache-01.js b/devtools/client/framework/test/browser_toolbox_options_disable_cache-01.js
index ed1ae4a62f22..da1365d37dea 100644
--- a/devtools/client/framework/test/browser_toolbox_options_disable_cache-01.js
+++ b/devtools/client/framework/test/browser_toolbox_options_disable_cache-01.js
@@ -11,9 +11,9 @@ requestLongerTimeout(2);
 // are not toggled.
 loadHelperScript("helper_disable_cache.js");
 
-add_task(async function () {
+add_task(function* () {
   // Disable rcwn to make cache behavior deterministic.
-  await pushPref("network.http.rcwn.enabled", false);
+  yield pushPref("network.http.rcwn.enabled", false);
 
   // Ensure that the setting is cleared after the test.
   registerCleanupFunction(() => {
@@ -23,15 +23,15 @@ add_task(async function () {
 
   // Initialise tabs: 1 and 2 with a toolbox, 3 and 4 without.
   for (let tab of tabs) {
-    await initTab(tab, tab.startToolbox);
+    yield initTab(tab, tab.startToolbox);
   }
 
   // Ensure cache is enabled for all tabs.
-  await checkCacheStateForAllTabs([true, true, true, true]);
+  yield checkCacheStateForAllTabs([true, true, true, true]);
 
   // Check the checkbox in tab 0 and ensure cache is disabled for tabs 0 and 1.
-  await setDisableCacheCheckboxChecked(tabs[0], true);
-  await checkCacheStateForAllTabs([false, false, true, true]);
+  yield setDisableCacheCheckboxChecked(tabs[0], true);
+  yield checkCacheStateForAllTabs([false, false, true, true]);
 
-  await finishUp();
+  yield finishUp();
 });
diff --git a/devtools/client/framework/test/browser_toolbox_options_disable_cache-02.js b/devtools/client/framework/test/browser_toolbox_options_disable_cache-02.js
index 27462d0c112d..5b255ba82e3f 100644
--- a/devtools/client/framework/test/browser_toolbox_options_disable_cache-02.js
+++ b/devtools/client/framework/test/browser_toolbox_options_disable_cache-02.js
@@ -11,9 +11,9 @@ requestLongerTimeout(2);
 // are toggled.
 loadHelperScript("helper_disable_cache.js");
 
-add_task(async function () {
+add_task(function* () {
   // Disable rcwn to make cache behavior deterministic.
-  await pushPref("network.http.rcwn.enabled", false);
+  yield pushPref("network.http.rcwn.enabled", false);
 
   // Ensure that the setting is cleared after the test.
   registerCleanupFunction(() => {
@@ -23,28 +23,28 @@ add_task(async function () {
 
   // Initialise tabs: 1 and 2 with a toolbox, 3 and 4 without.
   for (let tab of tabs) {
-    await initTab(tab, tab.startToolbox);
+    yield initTab(tab, tab.startToolbox);
   }
 
   // Disable cache in tab 0
-  await setDisableCacheCheckboxChecked(tabs[0], true);
+  yield setDisableCacheCheckboxChecked(tabs[0], true);
 
   // Open toolbox in tab 2 and ensure the cache is then disabled.
-  tabs[2].toolbox = await gDevTools.showToolbox(tabs[2].target, "options");
-  await checkCacheEnabled(tabs[2], false);
+  tabs[2].toolbox = yield gDevTools.showToolbox(tabs[2].target, "options");
+  yield checkCacheEnabled(tabs[2], false);
 
   // Close toolbox in tab 2 and ensure the cache is enabled again
-  await tabs[2].toolbox.destroy();
+  yield tabs[2].toolbox.destroy();
   tabs[2].target = TargetFactory.forTab(tabs[2].tab);
-  await checkCacheEnabled(tabs[2], true);
+  yield checkCacheEnabled(tabs[2], true);
 
   // Open toolbox in tab 2 and ensure the cache is then disabled.
-  tabs[2].toolbox = await gDevTools.showToolbox(tabs[2].target, "options");
-  await checkCacheEnabled(tabs[2], false);
+  tabs[2].toolbox = yield gDevTools.showToolbox(tabs[2].target, "options");
+  yield checkCacheEnabled(tabs[2], false);
 
   // Check the checkbox in tab 2 and ensure cache is enabled for all tabs.
-  await setDisableCacheCheckboxChecked(tabs[2], false);
-  await checkCacheStateForAllTabs([true, true, true, true]);
+  yield setDisableCacheCheckboxChecked(tabs[2], false);
+  yield checkCacheStateForAllTabs([true, true, true, true]);
 
-  await finishUp();
+  yield finishUp();
 });
diff --git a/devtools/client/framework/test/browser_toolbox_options_disable_js.js b/devtools/client/framework/test/browser_toolbox_options_disable_js.js
index aff23580c982..b0c14a805fd2 100644
--- a/devtools/client/framework/test/browser_toolbox_options_disable_js.js
+++ b/devtools/client/framework/test/browser_toolbox_options_disable_js.js
@@ -19,35 +19,35 @@ function testSelectTool(toolbox) {
   toolbox.selectTool("options");
 }
 
-let testToggleJS = async function (toolbox) {
+let testToggleJS = Task.async(function* (toolbox) {
   ok(true, "Toolbox selected via selectTool method");
 
-  await testJSEnabled();
-  await testJSEnabledIframe();
+  yield testJSEnabled();
+  yield testJSEnabledIframe();
 
   // Disable JS.
-  await toggleJS(toolbox);
+  yield toggleJS(toolbox);
 
-  await testJSDisabled();
-  await testJSDisabledIframe();
+  yield testJSDisabled();
+  yield testJSDisabledIframe();
 
   // Re-enable JS.
-  await toggleJS(toolbox);
+  yield toggleJS(toolbox);
 
-  await testJSEnabled();
-  await testJSEnabledIframe();
+  yield testJSEnabled();
+  yield testJSEnabledIframe();
 
   finishUp(toolbox);
-};
+});
 
-async function testJSEnabled() {
+function* testJSEnabled() {
   info("Testing that JS is enabled");
 
   // We use waitForTick here because switching docShell.allowJavascript to true
   // takes a while to become live.
-  await waitForTick();
+  yield waitForTick();
 
-  await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     let doc = content.document;
     let output = doc.getElementById("output");
     doc.querySelector("#logJSEnabled").click();
@@ -55,10 +55,10 @@ async function testJSEnabled() {
   });
 }
 
-async function testJSEnabledIframe() {
+function* testJSEnabledIframe() {
   info("Testing that JS is enabled in the iframe");
 
-  await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     let doc = content.document;
     let iframe = doc.querySelector("iframe");
     let iframeDoc = iframe.contentDocument;
@@ -69,7 +69,7 @@ async function testJSEnabledIframe() {
   });
 }
 
-async function toggleJS(toolbox) {
+function* toggleJS(toolbox) {
   let panel = toolbox.getCurrentPanel();
   let cbx = panel.panelDoc.getElementById("devtools-disable-javascript");
 
@@ -81,13 +81,13 @@ async function toggleJS(toolbox) {
 
   let browserLoaded = BrowserTestUtils.browserLoaded(gBrowser.selectedBrowser);
   cbx.click();
-  await browserLoaded;
+  yield browserLoaded;
 }
 
-async function testJSDisabled() {
+function* testJSDisabled() {
   info("Testing that JS is disabled");
 
-  await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     let doc = content.document;
     let output = doc.getElementById("output");
     doc.querySelector("#logJSDisabled").click();
@@ -97,10 +97,10 @@ async function testJSDisabled() {
   });
 }
 
-async function testJSDisabledIframe() {
+function* testJSDisabledIframe() {
   info("Testing that JS is disabled in the iframe");
 
-  await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     let doc = content.document;
     let iframe = doc.querySelector("iframe");
     let iframeDoc = iframe.contentDocument;
diff --git a/devtools/client/framework/test/browser_toolbox_races.js b/devtools/client/framework/test/browser_toolbox_races.js
index 03c2851b5901..e184e2953929 100644
--- a/devtools/client/framework/test/browser_toolbox_races.js
+++ b/devtools/client/framework/test/browser_toolbox_races.js
@@ -13,12 +13,12 @@ requestLongerTimeout(2);
 const URL = "data:text/html;charset=utf-8,Toggling devtools quickly";
 const {gDevToolsBrowser} = require("devtools/client/framework/devtools-browser");
 
-add_task(async function () {
+add_task(function* () {
   // Make sure this test starts with the selectedTool pref cleared. Previous
   // tests select various tools, and that sets this pref.
   Services.prefs.clearUserPref("devtools.toolbox.selectedTool");
 
-  let tab = await addTab(URL);
+  let tab = yield addTab(URL);
 
   let created = 0, ready = 0, destroy = 0, destroyed = 0;
   let onCreated = () => {
@@ -51,7 +51,7 @@ add_task(async function () {
     toggle();
 
     // Release the event loop to let a chance to actually create or destroy the toolbox!
-    await wait(50);
+    yield wait(50);
   }
   info("Toggled the toolbox 3 times");
 
@@ -60,11 +60,11 @@ add_task(async function () {
   // avoid races and be sure we end up we no toolbox and waited for all the
   // requests to be done.
   while (ready != 3) {
-    await wait(100);
+    yield wait(100);
   }
   toggle();
   while (destroyed != 3) {
-    await wait(100);
+    yield wait(100);
   }
 
   is(created, 3, "right number of created events");
diff --git a/devtools/client/framework/test/browser_toolbox_ready.js b/devtools/client/framework/test/browser_toolbox_ready.js
index dc8b4911879f..e1a59b3f0b64 100644
--- a/devtools/client/framework/test/browser_toolbox_ready.js
+++ b/devtools/client/framework/test/browser_toolbox_ready.js
@@ -5,17 +5,17 @@
 
 const TEST_URL = "data:text/html,test for toolbox being ready";
 
-add_task(async function () {
-  let tab = await addTab(TEST_URL);
+add_task(function* () {
+  let tab = yield addTab(TEST_URL);
   let target = TargetFactory.forTab(tab);
 
-  const toolbox = await gDevTools.showToolbox(target, "webconsole");
+  const toolbox = yield gDevTools.showToolbox(target, "webconsole");
   ok(toolbox.isReady, "toolbox isReady is set");
   ok(toolbox.threadClient, "toolbox has a thread client");
 
-  const toolbox2 = await gDevTools.showToolbox(toolbox.target, toolbox.toolId);
+  const toolbox2 = yield gDevTools.showToolbox(toolbox.target, toolbox.toolId);
   is(toolbox2, toolbox, "same toolbox");
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
 });
diff --git a/devtools/client/framework/test/browser_toolbox_remoteness_change.js b/devtools/client/framework/test/browser_toolbox_remoteness_change.js
index c43dfa656e00..b30d633faaa4 100644
--- a/devtools/client/framework/test/browser_toolbox_remoteness_change.js
+++ b/devtools/client/framework/test/browser_toolbox_remoteness_change.js
@@ -7,13 +7,13 @@ const URL_1 = "about:robots";
 const URL_2 = "data:text/html;charset=UTF-8," +
   encodeURIComponent("<div id=\"remote-page\">foo</div>");
 
-add_task(async function () {
+add_task(function* () {
   info("Open a tab on a URL supporting only running in parent process");
-  let tab = await addTab(URL_1);
+  let tab = yield addTab(URL_1);
   is(tab.linkedBrowser.currentURI.spec, URL_1, "We really are on the expected document");
   is(tab.linkedBrowser.getAttribute("remote"), "", "And running in parent process");
 
-  let toolbox = await openToolboxForTab(tab);
+  let toolbox = yield openToolboxForTab(tab);
 
   let onToolboxDestroyed = toolbox.once("destroyed");
   let onToolboxCreated = gDevTools.once("toolbox-created");
@@ -21,23 +21,23 @@ add_task(async function () {
   info("Navigate to a URL supporting remote process");
   let onLoaded = BrowserTestUtils.browserLoaded(tab.linkedBrowser);
   gBrowser.loadURI(URL_2);
-  await onLoaded;
+  yield onLoaded;
 
   is(tab.linkedBrowser.getAttribute("remote"), "true", "Navigated to a data: URI and switching to remote");
 
   info("Waiting for the toolbox to be destroyed");
-  await onToolboxDestroyed;
+  yield onToolboxDestroyed;
 
   info("Waiting for a new toolbox to be created");
-  toolbox = await onToolboxCreated;
+  toolbox = yield onToolboxCreated;
 
   info("Waiting for the new toolbox to be ready");
-  await toolbox.once("ready");
+  yield toolbox.once("ready");
 
   info("Veryify we are inspecting the new document");
-  let console = await toolbox.selectTool("webconsole");
+  let console = yield toolbox.selectTool("webconsole");
   let { jsterm } = console.hud;
-  let url = await jsterm.execute("document.location.href");
+  let url = yield jsterm.execute("document.location.href");
   // Uses includes as the old console frontend prints a timestamp
   ok(url.textContent.includes(URL_2), "The console inspects the second document");
 });
diff --git a/devtools/client/framework/test/browser_toolbox_select_event.js b/devtools/client/framework/test/browser_toolbox_select_event.js
index 465a328bd8de..ae104524e879 100644
--- a/devtools/client/framework/test/browser_toolbox_select_event.js
+++ b/devtools/client/framework/test/browser_toolbox_select_event.js
@@ -9,50 +9,50 @@ const PAGE_URL = "data:text/html;charset=utf-8,test select events";
 
 requestLongerTimeout(2);
 
-add_task(async function () {
-  let tab = await addTab(PAGE_URL);
+add_task(function* () {
+  let tab = yield addTab(PAGE_URL);
 
-  let toolbox = await openToolboxForTab(tab, "webconsole", "bottom");
-  await testSelectEvent("inspector");
-  await testSelectEvent("webconsole");
-  await testSelectEvent("styleeditor");
-  await testSelectEvent("inspector");
-  await testSelectEvent("webconsole");
-  await testSelectEvent("styleeditor");
+  let toolbox = yield openToolboxForTab(tab, "webconsole", "bottom");
+  yield testSelectEvent("inspector");
+  yield testSelectEvent("webconsole");
+  yield testSelectEvent("styleeditor");
+  yield testSelectEvent("inspector");
+  yield testSelectEvent("webconsole");
+  yield testSelectEvent("styleeditor");
 
-  await testToolSelectEvent("inspector");
-  await testToolSelectEvent("webconsole");
-  await testToolSelectEvent("styleeditor");
-  await toolbox.destroy();
+  yield testToolSelectEvent("inspector");
+  yield testToolSelectEvent("webconsole");
+  yield testToolSelectEvent("styleeditor");
+  yield toolbox.destroy();
 
-  toolbox = await openToolboxForTab(tab, "webconsole", "side");
-  await testSelectEvent("inspector");
-  await testSelectEvent("webconsole");
-  await testSelectEvent("styleeditor");
-  await testSelectEvent("inspector");
-  await testSelectEvent("webconsole");
-  await testSelectEvent("styleeditor");
-  await toolbox.destroy();
+  toolbox = yield openToolboxForTab(tab, "webconsole", "side");
+  yield testSelectEvent("inspector");
+  yield testSelectEvent("webconsole");
+  yield testSelectEvent("styleeditor");
+  yield testSelectEvent("inspector");
+  yield testSelectEvent("webconsole");
+  yield testSelectEvent("styleeditor");
+  yield toolbox.destroy();
 
-  toolbox = await openToolboxForTab(tab, "webconsole", "window");
-  await testSelectEvent("inspector");
-  await testSelectEvent("webconsole");
-  await testSelectEvent("styleeditor");
-  await testSelectEvent("inspector");
-  await testSelectEvent("webconsole");
-  await testSelectEvent("styleeditor");
-  await toolbox.destroy();
+  toolbox = yield openToolboxForTab(tab, "webconsole", "window");
+  yield testSelectEvent("inspector");
+  yield testSelectEvent("webconsole");
+  yield testSelectEvent("styleeditor");
+  yield testSelectEvent("inspector");
+  yield testSelectEvent("webconsole");
+  yield testSelectEvent("styleeditor");
+  yield toolbox.destroy();
 
-  await testSelectToolRace();
+  yield testSelectToolRace();
 
   /**
    * Assert that selecting the given toolId raises a select event
    * @param {toolId} Id of the tool to test
    */
-  async function testSelectEvent(toolId) {
+  function* testSelectEvent(toolId) {
     let onSelect = toolbox.once("select");
     toolbox.selectTool(toolId);
-    let id = await onSelect;
+    let id = yield onSelect;
     is(id, toolId, toolId + " selected");
   }
 
@@ -61,18 +61,18 @@ add_task(async function () {
    * selected event
    * @param {toolId} Id of the tool to test
    */
-  async function testToolSelectEvent(toolId) {
+  function* testToolSelectEvent(toolId) {
     let onSelected = toolbox.once(toolId + "-selected");
     toolbox.selectTool(toolId);
-    await onSelected;
+    yield onSelected;
     is(toolbox.currentToolId, toolId, toolId + " tool selected");
   }
 
   /**
    * Assert that two calls to selectTool won't race
    */
-  async function testSelectToolRace() {
-    let toolbox = await openToolboxForTab(tab, "webconsole");
+  function* testSelectToolRace() {
+    let toolbox = yield openToolboxForTab(tab, "webconsole");
     let selected = false;
     let onSelect = (event, id) => {
       if (selected) {
@@ -92,10 +92,10 @@ add_task(async function () {
     };
     p1.then(checkSelectToolResolution);
     p2.then(checkSelectToolResolution);
-    await p1;
-    await p2;
+    yield p1;
+    yield p2;
 
-    await toolbox.destroy();
+    yield toolbox.destroy();
   }
 });
 
diff --git a/devtools/client/framework/test/browser_toolbox_selected_tool_unavailable.js b/devtools/client/framework/test/browser_toolbox_selected_tool_unavailable.js
index 13cb75e1b26f..d7cc5c94dd68 100644
--- a/devtools/client/framework/test/browser_toolbox_selected_tool_unavailable.js
+++ b/devtools/client/framework/test/browser_toolbox_selected_tool_unavailable.js
@@ -25,23 +25,23 @@ const testToolDefinition = {
     }
 };
 
-add_task(async function () {
+add_task(function* () {
   gDevTools.registerTool(testToolDefinition);
-  let tab = await addTab("about:blank");
+  let tab = yield addTab("about:blank");
   let target = TargetFactory.forTab(tab);
 
-  let toolbox = await gDevTools.showToolbox(target, testToolDefinition.id);
+  let toolbox = yield gDevTools.showToolbox(target, testToolDefinition.id);
   is(toolbox.currentToolId, "test-tool", "test-tool was selected");
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
 
   // Make the previously selected tool unavailable.
   testToolDefinition.isTargetSupported = () => false;
 
   target = TargetFactory.forTab(tab);
-  toolbox = await gDevTools.showToolbox(target);
+  toolbox = yield gDevTools.showToolbox(target);
   is(toolbox.currentToolId, "webconsole", "web console was selected");
 
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   gDevTools.unregisterTool(testToolDefinition.id);
   tab = toolbox = target = null;
   gBrowser.removeCurrentTab();
diff --git a/devtools/client/framework/test/browser_toolbox_selectionchanged_event.js b/devtools/client/framework/test/browser_toolbox_selectionchanged_event.js
index 097195abb43b..950d4a250da6 100644
--- a/devtools/client/framework/test/browser_toolbox_selectionchanged_event.js
+++ b/devtools/client/framework/test/browser_toolbox_selectionchanged_event.js
@@ -7,14 +7,14 @@
 
 const PAGE_URL = "data:text/html;charset=utf-8,<body><div></div></body>";
 
-add_task(async function () {
-  let tab = await addTab(PAGE_URL);
-  let toolbox = await openToolboxForTab(tab, "inspector", "bottom");
+add_task(function* () {
+  let tab = yield addTab(PAGE_URL);
+  let toolbox = yield openToolboxForTab(tab, "inspector", "bottom");
   let inspector = toolbox.getCurrentPanel();
 
-  let root = await inspector.walker.getRootNode();
-  let body = await inspector.walker.querySelector(root, "body");
-  let node = await inspector.walker.querySelector(root, "div");
+  let root = yield inspector.walker.getRootNode();
+  let body = yield inspector.walker.querySelector(root, "body");
+  let node = yield inspector.walker.querySelector(root, "div");
 
   is(inspector.selection.nodeFront, body, "Body is selected by default");
 
@@ -24,7 +24,7 @@ add_task(async function () {
   info("Select the div and wait for the selection-changed event to be fired.");
   inspector.selection.setNodeFront(node, "browser-context-menu");
 
-  await onSelectionChanged;
+  yield onSelectionChanged;
 
   is(inspector.selection.nodeFront, node, "Div is now selected");
 
@@ -34,7 +34,7 @@ add_task(async function () {
   info("Clear the selection and wait for the selection-changed event to be fired.");
   inspector.selection.setNodeFront(undefined, "browser-context-menu");
 
-  await onClearSelectionChanged;
+  yield onClearSelectionChanged;
 
   is(inspector.selection.nodeFront, undefined, "The selection is undefined as expected");
 });
diff --git a/devtools/client/framework/test/browser_toolbox_sidebar_existing_tabs.js b/devtools/client/framework/test/browser_toolbox_sidebar_existing_tabs.js
index 9e99b3b073c1..9ac3a126bae6 100644
--- a/devtools/client/framework/test/browser_toolbox_sidebar_existing_tabs.js
+++ b/devtools/client/framework/test/browser_toolbox_sidebar_existing_tabs.js
@@ -25,13 +25,13 @@ const testToolDefinition = {
   }
 };
 
-add_task(async function () {
-  let tab = await addTab("about:blank");
+add_task(function* () {
+  let tab = yield addTab("about:blank");
 
   let target = TargetFactory.forTab(tab);
 
   gDevTools.registerTool(testToolDefinition);
-  let toolbox = await gDevTools.showToolbox(target, testToolDefinition.id);
+  let toolbox = yield gDevTools.showToolbox(target, testToolDefinition.id);
 
   let toolPanel = toolbox.getPanel(testToolDefinition.id);
   let tabbox = toolPanel.panelDoc.getElementById("sidebar");
@@ -63,7 +63,7 @@ add_task(async function () {
   ok(!sidebar.getTabPanel("tabpanel2"), "Tabpanel 2 was removed correctly");
 
   sidebar.destroy();
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gDevTools.unregisterTool(testToolDefinition.id);
   gBrowser.removeCurrentTab();
 });
diff --git a/devtools/client/framework/test/browser_toolbox_sidebar_overflow_menu.js b/devtools/client/framework/test/browser_toolbox_sidebar_overflow_menu.js
index 5216c13a687f..5f6914a2f76c 100644
--- a/devtools/client/framework/test/browser_toolbox_sidebar_overflow_menu.js
+++ b/devtools/client/framework/test/browser_toolbox_sidebar_overflow_menu.js
@@ -26,12 +26,12 @@ const testToolDefinition = {
   }
 };
 
-add_task(async function () {
-  let tab = await addTab("about:blank");
+add_task(function* () {
+  let tab = yield addTab("about:blank");
   let target = TargetFactory.forTab(tab);
 
   gDevTools.registerTool(testToolDefinition);
-  let toolbox = await gDevTools.showToolbox(target, testToolDefinition.id);
+  let toolbox = yield gDevTools.showToolbox(target, testToolDefinition.id);
 
   let toolPanel = toolbox.getPanel(testToolDefinition.id);
   let tabbox = toolPanel.panelDoc.getElementById("sidebar");
@@ -73,8 +73,8 @@ add_task(async function () {
   sidebar._onTabBoxUnderflow();
   is(allTabsMenu.getAttribute("hidden"), "true", "The all-tabs menu is hidden");
 
-  await sidebar.destroy();
-  await toolbox.destroy();
+  yield sidebar.destroy();
+  yield toolbox.destroy();
   gDevTools.unregisterTool(testToolDefinition.id);
   gBrowser.removeCurrentTab();
 });
diff --git a/devtools/client/framework/test/browser_toolbox_split_console.js b/devtools/client/framework/test/browser_toolbox_split_console.js
index 6a8560c3253e..18bd709ff011 100644
--- a/devtools/client/framework/test/browser_toolbox_split_console.js
+++ b/devtools/client/framework/test/browser_toolbox_split_console.js
@@ -16,26 +16,26 @@ const URL = "data:text/html;charset=utf8,test split console key delegation";
 
 // Force the old debugger UI since it's directly used (see Bug 1301705)
 Services.prefs.setBoolPref("devtools.debugger.new-debugger-frontend", false);
-registerCleanupFunction(function() {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.debugger.new-debugger-frontend");
 });
 
-add_task(async function () {
-  let tab = await addTab(URL);
+add_task(function* () {
+  let tab = yield addTab(URL);
   let target = TargetFactory.forTab(tab);
-  gToolbox = await gDevTools.showToolbox(target, "jsdebugger");
+  gToolbox = yield gDevTools.showToolbox(target, "jsdebugger");
   panelWin = gToolbox.getPanel("jsdebugger").panelWin;
 
-  await gToolbox.openSplitConsole();
-  await testIsSplitConsoleFocused();
-  await testUseKeyWithSplitConsole();
-  await testUseKeyWithSplitConsoleWrongTool();
+  yield gToolbox.openSplitConsole();
+  yield testIsSplitConsoleFocused();
+  yield testUseKeyWithSplitConsole();
+  yield testUseKeyWithSplitConsoleWrongTool();
 
-  await cleanup();
+  yield cleanup();
 });
 
-async function testIsSplitConsoleFocused() {
-  await gToolbox.openSplitConsole();
+function* testIsSplitConsoleFocused() {
+  yield gToolbox.openSplitConsole();
   // The newly opened split console should have focus
   ok(gToolbox.isSplitConsoleFocused(), "Split console is focused");
   panelWin.focus();
@@ -43,7 +43,7 @@ async function testIsSplitConsoleFocused() {
 }
 
 // A key bound to the selected tool should trigger it's command
-function testUseKeyWithSplitConsole() {
+function* testUseKeyWithSplitConsole() {
   let commandCalled = false;
 
   info("useKeyWithSplitConsole on debugger while debugger is focused");
@@ -60,7 +60,7 @@ function testUseKeyWithSplitConsole() {
 }
 
 // A key bound to a *different* tool should not trigger it's command
-function testUseKeyWithSplitConsoleWrongTool() {
+function* testUseKeyWithSplitConsoleWrongTool() {
   let commandCalled = false;
 
   info("useKeyWithSplitConsole on inspector while debugger is focused");
@@ -76,8 +76,8 @@ function testUseKeyWithSplitConsoleWrongTool() {
   ok(!commandCalled, "Shortcut key shouldn't trigger the command");
 }
 
-async function cleanup() {
-  await gToolbox.destroy();
+function* cleanup() {
+  yield gToolbox.destroy();
   gBrowser.removeCurrentTab();
   gToolbox = panelWin = null;
 }
diff --git a/devtools/client/framework/test/browser_toolbox_tabsswitch_shortcuts.js b/devtools/client/framework/test/browser_toolbox_tabsswitch_shortcuts.js
index 86a105dce7c6..b9401f768290 100644
--- a/devtools/client/framework/test/browser_toolbox_tabsswitch_shortcuts.js
+++ b/devtools/client/framework/test/browser_toolbox_tabsswitch_shortcuts.js
@@ -12,54 +12,54 @@ var {Toolbox} = require("devtools/client/framework/toolbox");
 const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");
 
-add_task(async function () {
-  let tab = await addTab("about:blank");
+add_task(function* () {
+  let tab = yield addTab("about:blank");
   let target = TargetFactory.forTab(tab);
-  await target.makeRemote();
+  yield target.makeRemote();
 
   let toolIDs = gDevTools.getToolDefinitionArray()
                          .filter(def => def.isTargetSupported(target))
                          .map(def => def.id);
 
-  let toolbox = await gDevTools.showToolbox(target, toolIDs[0], Toolbox.HostType.BOTTOM);
+  let toolbox = yield gDevTools.showToolbox(target, toolIDs[0], Toolbox.HostType.BOTTOM);
   let nextShortcut = L10N.getStr("toolbox.nextTool.key");
   let prevShortcut = L10N.getStr("toolbox.previousTool.key");
 
   // Iterate over all tools, starting from options to netmonitor, in normal
   // order.
   for (let i = 1; i < toolIDs.length; i++) {
-    await testShortcuts(toolbox, i, nextShortcut, toolIDs);
+    yield testShortcuts(toolbox, i, nextShortcut, toolIDs);
   }
 
   // Iterate again, in the same order, starting from netmonitor (so next one is
   // 0: options).
   for (let i = 0; i < toolIDs.length; i++) {
-    await testShortcuts(toolbox, i, nextShortcut, toolIDs);
+    yield testShortcuts(toolbox, i, nextShortcut, toolIDs);
   }
 
   // Iterate over all tools in reverse order, starting from netmonitor to
   // options.
   for (let i = toolIDs.length - 2; i >= 0; i--) {
-    await testShortcuts(toolbox, i, prevShortcut, toolIDs);
+    yield testShortcuts(toolbox, i, prevShortcut, toolIDs);
   }
 
   // Iterate again, in reverse order again, starting from options (so next one
   // is length-1: netmonitor).
   for (let i = toolIDs.length - 1; i >= 0; i--) {
-    await testShortcuts(toolbox, i, prevShortcut, toolIDs);
+    yield testShortcuts(toolbox, i, prevShortcut, toolIDs);
   }
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
   gBrowser.removeCurrentTab();
 });
 
-async function testShortcuts(toolbox, index, shortcut, toolIDs) {
+function* testShortcuts(toolbox, index, shortcut, toolIDs) {
   info("Testing shortcut to switch to tool " + index + ":" + toolIDs[index] +
        " using shortcut " + shortcut);
 
   let onToolSelected = toolbox.once("select");
   synthesizeKeyShortcut(shortcut);
-  let id = await onToolSelected;
+  let id = yield onToolSelected;
 
   info("toolbox-select event from " + id);
 
diff --git a/devtools/client/framework/test/browser_toolbox_target.js b/devtools/client/framework/test/browser_toolbox_target.js
index 97ac7fd9430c..68639c50121e 100644
--- a/devtools/client/framework/test/browser_toolbox_target.js
+++ b/devtools/client/framework/test/browser_toolbox_target.js
@@ -7,7 +7,7 @@
 // iframe while defining which document to debug by setting a `target`
 // attribute refering to the document to debug.
 
-add_task(async function () {
+add_task(function *() {
   // iframe loads the document to debug
   let iframe = document.createElement("browser");
   iframe.setAttribute("type", "content");
@@ -15,7 +15,7 @@ add_task(async function () {
 
   let onLoad = once(iframe, "load", true);
   iframe.setAttribute("src", "data:text/html,document to debug");
-  await onLoad;
+  yield onLoad;
   is(iframe.contentWindow.document.body.innerHTML, "document to debug");
 
   // toolbox loads the toolbox document
@@ -29,12 +29,12 @@ add_task(async function () {
 
   onLoad = once(toolboxIframe, "load", true);
   toolboxIframe.setAttribute("src", "about:devtools-toolbox?target");
-  await onLoad;
+  yield onLoad;
 
   // Also wait for toolbox-ready, as toolbox document load isn't enough, there
   // is plenty of asynchronous steps during toolbox load
   info("Waiting for toolbox-ready");
-  let toolbox = await onToolboxReady;
+  let toolbox = yield onToolboxReady;
 
   let onToolboxDestroyed = gDevTools.once("toolbox-destroyed");
   let onTabActorDetached = once(toolbox.target.client, "tabDetached");
@@ -45,7 +45,7 @@ add_task(async function () {
   // And wait for toolbox-destroyed as toolbox unload is also full of
   // asynchronous operation that outlast unload event
   info("Waiting for toolbox-destroyed");
-  await onToolboxDestroyed;
+  yield onToolboxDestroyed;
   info("Toolbox destroyed");
 
   // Also wait for tabDetached. Toolbox destroys the Target which calls
@@ -54,7 +54,7 @@ add_task(async function () {
   // cleanup. If we do not wait for it and starts removing debugged document,
   // the actor is still considered as being attached and continues processing
   // events.
-  await onTabActorDetached;
+  yield onTabActorDetached;
 
   iframe.remove();
 });
diff --git a/devtools/client/framework/test/browser_toolbox_theme_registration.js b/devtools/client/framework/test/browser_toolbox_theme_registration.js
index 020a882feaaf..0a259f9916d5 100644
--- a/devtools/client/framework/test/browser_toolbox_theme_registration.js
+++ b/devtools/client/framework/test/browser_toolbox_theme_registration.js
@@ -13,12 +13,12 @@ const LIGHT_THEME_NAME = "light";
 
 var toolbox;
 
-add_task(async function themeRegistration() {
-  let tab = await addTab("data:text/html,test");
+add_task(function* themeRegistration() {
+  let tab = yield addTab("data:text/html,test");
   let target = TargetFactory.forTab(tab);
-  toolbox = await gDevTools.showToolbox(target, "options");
+  toolbox = yield gDevTools.showToolbox(target, "options");
 
-  let themeId = await new Promise(resolve => {
+  let themeId = yield new Promise(resolve => {
     gDevTools.once("theme-registered", (e, registeredThemeId) => {
       resolve(registeredThemeId);
     });
@@ -36,7 +36,7 @@ add_task(async function themeRegistration() {
   ok(gDevTools.getThemeDefinitionMap().has(themeId), "theme added to map");
 });
 
-add_task(async function themeInOptionsPanel() {
+add_task(function* themeInOptionsPanel() {
   let panelWin = toolbox.getCurrentPanel().panelWin;
   let doc = panelWin.frameElement.contentDocument;
   let themeBox = doc.getElementById("devtools-theme-box");
@@ -63,7 +63,7 @@ add_task(async function themeInOptionsPanel() {
   testThemeOption.click();
 
   info("Waiting for theme to finish loading");
-  await onThemeSwithComplete;
+  yield onThemeSwithComplete;
 
   is(gDevTools.getTheme(), TEST_THEME_NAME, "getTheme returns the expected theme");
   is(eventsRecorded.pop(), TEST_THEME_NAME, "theme-changed fired with the expected theme");
@@ -77,7 +77,7 @@ add_task(async function themeInOptionsPanel() {
   lightThemeOption.click();
 
   info("Waiting for theme to finish loading");
-  await onThemeSwithComplete;
+  yield onThemeSwithComplete;
 
   is(gDevTools.getTheme(), LIGHT_THEME_NAME, "getTheme returns the expected theme");
   is(eventsRecorded.pop(), LIGHT_THEME_NAME, "theme-changed fired with the expected theme");
@@ -88,14 +88,14 @@ add_task(async function themeInOptionsPanel() {
   onThemeSwithComplete = once(panelWin, "theme-switch-complete");
   // Select test theme again.
   testThemeOption.click();
-  await onThemeSwithComplete;
+  yield onThemeSwithComplete;
   is(gDevTools.getTheme(), TEST_THEME_NAME, "getTheme returns the expected theme");
   is(eventsRecorded.pop(), TEST_THEME_NAME, "theme-changed fired with the expected theme");
 
   gDevTools.off("theme-changed", onThemeChanged);
 });
 
-add_task(async function themeUnregistration() {
+add_task(function* themeUnregistration() {
   let panelWin = toolbox.getCurrentPanel().panelWin;
   let onUnRegisteredTheme = once(gDevTools, "theme-unregistered");
   let onThemeSwitchComplete = once(panelWin, "theme-switch-complete");
@@ -107,8 +107,8 @@ add_task(async function themeUnregistration() {
   gDevTools.on("theme-changed", onThemeChanged);
 
   gDevTools.unregisterTheme(TEST_THEME_NAME);
-  await onUnRegisteredTheme;
-  await onThemeSwitchComplete;
+  yield onUnRegisteredTheme;
+  yield onThemeSwitchComplete;
 
   is(gDevTools.getTheme(), LIGHT_THEME_NAME, "getTheme returns the expected theme");
   is(eventsRecorded.pop(), LIGHT_THEME_NAME, "theme-changed fired with the expected theme");
@@ -125,7 +125,7 @@ add_task(async function themeUnregistration() {
   gDevTools.off("theme-changed", onThemeChanged);
 });
 
-add_task(async function cleanup() {
-  await toolbox.destroy();
+add_task(function* cleanup() {
+  yield toolbox.destroy();
   toolbox = null;
 });
diff --git a/devtools/client/framework/test/browser_toolbox_toggle.js b/devtools/client/framework/test/browser_toolbox_toggle.js
index 845c9cc7700b..d5b6d0e961d1 100644
--- a/devtools/client/framework/test/browser_toolbox_toggle.js
+++ b/devtools/client/framework/test/browser_toolbox_toggle.js
@@ -12,7 +12,7 @@ const URL = "data:text/html;charset=utf-8,Toggling devtools using shortcuts";
 
 var {Toolbox} = require("devtools/client/framework/toolbox");
 
-add_task(async function () {
+add_task(function* () {
   // Make sure this test starts with the selectedTool pref cleared. Previous
   // tests select various tools, and that sets this pref.
   Services.prefs.clearUserPref("devtools.toolbox.selectedTool");
@@ -21,7 +21,7 @@ add_task(async function () {
   // - toolbox-key-toggle in devtools/client/framework/toolbox-window.xul
   // - key_devToolboxMenuItem in browser/base/content/browser.xul
   info("Test toggle using CTRL+SHIFT+I/CMD+ALT+I");
-  await testToggle("I", {
+  yield testToggle("I", {
     accelKey: true,
     shiftKey: !navigator.userAgent.match(/Mac/),
     altKey: navigator.userAgent.match(/Mac/)
@@ -29,20 +29,20 @@ add_task(async function () {
 
   // Test with F12 ; no modifiers
   info("Test toggle using F12");
-  await testToggle("VK_F12", {});
+  yield testToggle("VK_F12", {});
 });
 
-async function testToggle(key, modifiers) {
-  let tab = await addTab(URL + " ; key : '" + key + "'");
-  await gDevTools.showToolbox(TargetFactory.forTab(tab));
+function* testToggle(key, modifiers) {
+  let tab = yield addTab(URL + " ; key : '" + key + "'");
+  yield gDevTools.showToolbox(TargetFactory.forTab(tab));
 
-  await testToggleDockedToolbox(tab, key, modifiers);
-  await testToggleDetachedToolbox(tab, key, modifiers);
+  yield testToggleDockedToolbox(tab, key, modifiers);
+  yield testToggleDetachedToolbox(tab, key, modifiers);
 
-  await cleanup();
+  yield cleanup();
 }
 
-async function testToggleDockedToolbox(tab, key, modifiers) {
+function* testToggleDockedToolbox(tab, key, modifiers) {
   let toolbox = getToolboxForTab(tab);
 
   isnot(toolbox.hostType, Toolbox.HostType.WINDOW,
@@ -51,33 +51,33 @@ async function testToggleDockedToolbox(tab, key, modifiers) {
   info("verify docked toolbox is destroyed when using toggle key");
   let onToolboxDestroyed = once(gDevTools, "toolbox-destroyed");
   EventUtils.synthesizeKey(key, modifiers);
-  await onToolboxDestroyed;
+  yield onToolboxDestroyed;
   ok(true, "Docked toolbox is destroyed when using a toggle key");
 
   info("verify new toolbox is created when using toggle key");
   let onToolboxReady = once(gDevTools, "toolbox-ready");
   EventUtils.synthesizeKey(key, modifiers);
-  await onToolboxReady;
+  yield onToolboxReady;
   ok(true, "Toolbox is created by using when toggle key");
 }
 
-async function testToggleDetachedToolbox(tab, key, modifiers) {
+function* testToggleDetachedToolbox(tab, key, modifiers) {
   let toolbox = getToolboxForTab(tab);
 
   info("change the toolbox hostType to WINDOW");
 
-  await toolbox.switchHost(Toolbox.HostType.WINDOW);
+  yield toolbox.switchHost(Toolbox.HostType.WINDOW);
   is(toolbox.hostType, Toolbox.HostType.WINDOW,
     "Toolbox opened on separate window");
 
   info("Wait for focus on the toolbox window");
-  await new Promise(res => waitForFocus(res, toolbox.win));
+  yield new Promise(res => waitForFocus(res, toolbox.win));
 
   info("Focus main window to put the toolbox window in the background");
 
   let onMainWindowFocus = once(window, "focus");
   window.focus();
-  await onMainWindowFocus;
+  yield onMainWindowFocus;
   ok(true, "Main window focused");
 
   info("Verify windowed toolbox is focused instead of closed when using " +
@@ -85,7 +85,7 @@ async function testToggleDetachedToolbox(tab, key, modifiers) {
   let toolboxWindow = toolbox.win.top;
   let onToolboxWindowFocus = once(toolboxWindow, "focus", true);
   EventUtils.synthesizeKey(key, modifiers);
-  await onToolboxWindowFocus;
+  yield onToolboxWindowFocus;
   ok(true, "Toolbox focused and not destroyed");
 
   info("Verify windowed toolbox is destroyed when using toggle key from its " +
@@ -93,7 +93,7 @@ async function testToggleDetachedToolbox(tab, key, modifiers) {
 
   let onToolboxDestroyed = once(gDevTools, "toolbox-destroyed");
   EventUtils.synthesizeKey(key, modifiers, toolboxWindow);
-  await onToolboxDestroyed;
+  yield onToolboxDestroyed;
   ok(true, "Toolbox destroyed");
 }
 
@@ -101,7 +101,7 @@ function getToolboxForTab(tab) {
   return gDevTools.getToolbox(TargetFactory.forTab(tab));
 }
 
-function cleanup() {
+function* cleanup() {
   Services.prefs.setCharPref("devtools.toolbox.host",
     Toolbox.HostType.BOTTOM);
   gBrowser.removeCurrentTab();
diff --git a/devtools/client/framework/test/browser_toolbox_tool_ready.js b/devtools/client/framework/test/browser_toolbox_tool_ready.js
index 2286911389c5..e7fb1f9c17ae 100644
--- a/devtools/client/framework/test/browser_toolbox_tool_ready.js
+++ b/devtools/client/framework/test/browser_toolbox_tool_ready.js
@@ -8,7 +8,7 @@
 requestLongerTimeout(5);
 
 function performChecks(target) {
-  return (async function () {
+  return Task.spawn(function* () {
     let toolIds = gDevTools.getToolDefinitionArray()
                            .filter(def => def.isTargetSupported(target))
                            .map(def => def.id);
@@ -18,7 +18,7 @@ function performChecks(target) {
       let toolId = toolIds[index];
 
       info("About to open " + index + "/" + toolId);
-      toolbox = await gDevTools.showToolbox(target, toolId);
+      toolbox = yield gDevTools.showToolbox(target, toolId);
       ok(toolbox, "toolbox exists for " + toolId);
       is(toolbox.currentToolId, toolId, "currentToolId should be " + toolId);
 
@@ -26,17 +26,17 @@ function performChecks(target) {
       ok(panel.isReady, toolId + " panel should be ready");
     }
 
-    await toolbox.destroy();
-  })();
+    yield toolbox.destroy();
+  });
 }
 
 function test() {
-  Task.spawn(async function () {
+  Task.spawn(function* () {
     toggleAllTools(true);
-    let tab = await addTab("about:blank");
+    let tab = yield addTab("about:blank");
     let target = TargetFactory.forTab(tab);
-    await target.makeRemote();
-    await performChecks(target);
+    yield target.makeRemote();
+    yield performChecks(target);
     gBrowser.removeCurrentTab();
     toggleAllTools(false);
     finish();
diff --git a/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js b/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js
index ba254a5a9b7e..434b05fbaa90 100644
--- a/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js
+++ b/devtools/client/framework/test/browser_toolbox_tool_remote_reopen.js
@@ -38,7 +38,7 @@ requestLongerTimeout(2);
  */
 
 function runTools(target) {
-  return (async function () {
+  return Task.spawn(function* () {
     let toolIds = gDevTools.getToolDefinitionArray()
                            .filter(def => def.isTargetSupported(target))
                            .map(def => def.id);
@@ -48,7 +48,7 @@ function runTools(target) {
       let toolId = toolIds[index];
 
       info("About to open " + index + "/" + toolId);
-      toolbox = await gDevTools.showToolbox(target, toolId, "window");
+      toolbox = yield gDevTools.showToolbox(target, toolId, "window");
       ok(toolbox, "toolbox exists for " + toolId);
       is(toolbox.currentToolId, toolId, "currentToolId should be " + toolId);
 
@@ -56,8 +56,8 @@ function runTools(target) {
       ok(panel.isReady, toolId + " panel should be ready");
     }
 
-    await toolbox.destroy();
-  })();
+    yield toolbox.destroy();
+  });
 }
 
 function getClient() {
@@ -88,13 +88,13 @@ function getTarget(client) {
 }
 
 function test() {
-  Task.spawn(async function () {
+  Task.spawn(function* () {
     toggleAllTools(true);
-    await addTab("about:blank");
+    yield addTab("about:blank");
 
-    let client = await getClient();
-    let target = await getTarget(client);
-    await runTools(target);
+    let client = yield getClient();
+    let target = yield getTarget(client);
+    yield runTools(target);
 
     // Actor fronts should be destroyed now that the toolbox has closed, but
     // look for any that remain.
diff --git a/devtools/client/framework/test/browser_toolbox_toolbar_overflow.js b/devtools/client/framework/test/browser_toolbox_toolbar_overflow.js
index f0ffc2f6064c..231f49df8c59 100644
--- a/devtools/client/framework/test/browser_toolbox_toolbar_overflow.js
+++ b/devtools/client/framework/test/browser_toolbox_toolbar_overflow.js
@@ -10,11 +10,11 @@
 // toolbar starts to present an overflow.
 let { Toolbox } = require("devtools/client/framework/toolbox");
 
-add_task(async function () {
-  let tab = await addTab("about:blank");
+add_task(function* () {
+  let tab = yield addTab("about:blank");
 
   info("Open devtools on the Inspector in a separate window");
-  let toolbox = await openToolboxForTab(tab, "inspector", Toolbox.HostType.WINDOW);
+  let toolbox = yield openToolboxForTab(tab, "inspector", Toolbox.HostType.WINDOW);
 
   let hostWindow = toolbox.win.parent;
   let originalWidth = hostWindow.outerWidth;
@@ -23,7 +23,7 @@ add_task(async function () {
   info("Resize devtools window to a width that should not trigger any overflow");
   let onResize = once(hostWindow, "resize");
   hostWindow.resizeTo(640, 300);
-  await onResize;
+  yield onResize;
 
   let allToolsButton = toolbox.doc.querySelector(".all-tools-menu");
   ok(!allToolsButton, "The all tools button is not displayed");
@@ -31,16 +31,16 @@ add_task(async function () {
   info("Resize devtools window to a width that should trigger an overflow");
   onResize = once(hostWindow, "resize");
   hostWindow.resizeTo(300, 300);
-  await onResize;
+  yield onResize;
 
   info("Wait until the all tools button is available");
-  await waitUntil(() => toolbox.doc.querySelector(".all-tools-menu"));
+  yield waitUntil(() => toolbox.doc.querySelector(".all-tools-menu"));
 
   allToolsButton = toolbox.doc.querySelector(".all-tools-menu");
   ok(allToolsButton, "The all tools button is displayed");
 
   info("Open the all-tools-menupopup and verify that the inspector button is checked");
-  let menuPopup = await openAllToolsMenu(toolbox);
+  let menuPopup = yield openAllToolsMenu(toolbox);
 
   let inspectorButton = toolbox.doc.querySelector("#all-tools-menupopup-inspector");
   ok(inspectorButton, "The inspector button is available");
@@ -53,15 +53,15 @@ add_task(async function () {
   info("Switch to the webconsole using the all-tools-menupopup popup");
   let onSelected = toolbox.once("webconsole-selected");
   consoleButton.click();
-  await onSelected;
+  yield onSelected;
 
   info("Closing the all-tools-menupopup popup");
   let onPopupHidden = once(menuPopup, "popuphidden");
   menuPopup.hidePopup();
-  await onPopupHidden;
+  yield onPopupHidden;
 
   info("Re-open the all-tools-menupopup and verify that the console button is checked");
-  menuPopup = await openAllToolsMenu(toolbox);
+  menuPopup = yield openAllToolsMenu(toolbox);
 
   inspectorButton = toolbox.doc.querySelector("#all-tools-menupopup-inspector");
   ok(!inspectorButton.getAttribute("checked"), "The inspector button is not checked");
@@ -73,7 +73,7 @@ add_task(async function () {
   hostWindow.resizeTo(originalWidth, originalHeight);
 });
 
-async function openAllToolsMenu(toolbox) {
+function* openAllToolsMenu(toolbox) {
   let allToolsButton = toolbox.doc.querySelector(".all-tools-menu");
   EventUtils.synthesizeMouseAtCenter(allToolsButton, {}, toolbox.win);
 
@@ -81,7 +81,7 @@ async function openAllToolsMenu(toolbox) {
   ok(menuPopup, "all-tools-menupopup is available");
 
   info("Waiting for the menu popup to be displayed");
-  await waitUntil(() => menuPopup && menuPopup.state === "open");
+  yield waitUntil(() => menuPopup && menuPopup.state === "open");
 
   return menuPopup;
 }
diff --git a/devtools/client/framework/test/browser_toolbox_view_source_01.js b/devtools/client/framework/test/browser_toolbox_view_source_01.js
index 1365740967f2..5a9a6d9b0eef 100644
--- a/devtools/client/framework/test/browser_toolbox_view_source_01.js
+++ b/devtools/client/framework/test/browser_toolbox_view_source_01.js
@@ -13,14 +13,14 @@ var JS_URL = `${URL_ROOT}code_math.js`;
 
 // Force the old debugger UI since it's directly used (see Bug 1301705)
 Services.prefs.setBoolPref("devtools.debugger.new-debugger-frontend", false);
-registerCleanupFunction(function() {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.debugger.new-debugger-frontend");
 });
 
-async function viewSource() {
-  let toolbox = await openNewTabAndToolbox(URL);
+function* viewSource() {
+  let toolbox = yield openNewTabAndToolbox(URL);
 
-  await toolbox.viewSourceInDebugger(JS_URL, 2);
+  yield toolbox.viewSourceInDebugger(JS_URL, 2);
 
   let debuggerPanel = toolbox.getPanel("jsdebugger");
   ok(debuggerPanel, "The debugger panel was opened.");
@@ -34,12 +34,12 @@ async function viewSource() {
   is(DebuggerView.editor.getCursor().line + 1, 2,
     "The correct line is highlighted in the debugger's source editor.");
 
-  await closeToolboxAndTab(toolbox);
+  yield closeToolboxAndTab(toolbox);
   finish();
 }
 
 function test() {
-  viewSource().then(finish, (aError) => {
+  Task.spawn(viewSource).then(finish, (aError) => {
     ok(false, "Got an error: " + aError.message + "\n" + aError.stack);
     finish();
   });
diff --git a/devtools/client/framework/test/browser_toolbox_view_source_02.js b/devtools/client/framework/test/browser_toolbox_view_source_02.js
index 94798ff0aed8..c18e885cf285 100644
--- a/devtools/client/framework/test/browser_toolbox_view_source_02.js
+++ b/devtools/client/framework/test/browser_toolbox_view_source_02.js
@@ -12,18 +12,18 @@ var JS_URL = `${URL_ROOT}code_math.js`;
 
 // Force the old debugger UI since it's directly used (see Bug 1301705)
 Services.prefs.setBoolPref("devtools.debugger.new-debugger-frontend", false);
-registerCleanupFunction(function() {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.debugger.new-debugger-frontend");
 });
 
-async function viewSource() {
-  let toolbox = await openNewTabAndToolbox(URL);
-  let { panelWin: debuggerWin } = await toolbox.selectTool("jsdebugger");
+function* viewSource() {
+  let toolbox = yield openNewTabAndToolbox(URL);
+  let { panelWin: debuggerWin } = yield toolbox.selectTool("jsdebugger");
   let debuggerEvents = debuggerWin.EVENTS;
   let { DebuggerView } = debuggerWin;
   let Sources = DebuggerView.Sources;
 
-  await debuggerWin.once(debuggerEvents.SOURCE_SHOWN);
+  yield debuggerWin.once(debuggerEvents.SOURCE_SHOWN);
   ok("A source was shown in the debugger.");
 
   is(Sources.selectedValue, getSourceActor(Sources, JS_URL),
@@ -31,7 +31,7 @@ async function viewSource() {
   is(DebuggerView.editor.getCursor().line, 0,
     "The correct line is initially highlighted in the debugger's source editor.");
 
-  await toolbox.viewSourceInDebugger(JS_URL, 2);
+  yield toolbox.viewSourceInDebugger(JS_URL, 2);
 
   let debuggerPanel = toolbox.getPanel("jsdebugger");
   ok(debuggerPanel, "The debugger panel was opened.");
@@ -42,12 +42,12 @@ async function viewSource() {
   is(DebuggerView.editor.getCursor().line + 1, 2,
     "The correct line is highlighted in the debugger's source editor.");
 
-  await closeToolboxAndTab(toolbox);
+  yield closeToolboxAndTab(toolbox);
   finish();
 }
 
 function test() {
-  viewSource().then(finish, (aError) => {
+  Task.spawn(viewSource).then(finish, (aError) => {
     ok(false, "Got an error: " + aError.message + "\n" + aError.stack);
     finish();
   });
diff --git a/devtools/client/framework/test/browser_toolbox_view_source_03.js b/devtools/client/framework/test/browser_toolbox_view_source_03.js
index 587fff6957ce..2d2cda76f38c 100644
--- a/devtools/client/framework/test/browser_toolbox_view_source_03.js
+++ b/devtools/client/framework/test/browser_toolbox_view_source_03.js
@@ -11,10 +11,10 @@
 var URL = `${URL_ROOT}doc_viewsource.html`;
 var CSS_URL = `${URL_ROOT}doc_theme.css`;
 
-async function viewSource() {
-  let toolbox = await openNewTabAndToolbox(URL);
+function* viewSource() {
+  let toolbox = yield openNewTabAndToolbox(URL);
 
-  let fileFound = await toolbox.viewSourceInStyleEditor(CSS_URL, 2);
+  let fileFound = yield toolbox.viewSourceInStyleEditor(CSS_URL, 2);
   ok(fileFound, "viewSourceInStyleEditor should resolve to true if source found.");
 
   let stylePanel = toolbox.getPanel("styleeditor");
@@ -28,12 +28,12 @@ async function viewSource() {
   is(UI.selectedEditor.sourceEditor.getCursor().line + 1, 2,
     "The correct line is highlighted in the style editor's source editor.");
 
-  await closeToolboxAndTab(toolbox);
+  yield closeToolboxAndTab(toolbox);
   finish();
 }
 
 function test() {
-  viewSource().then(finish, (aError) => {
+  Task.spawn(viewSource).then(finish, (aError) => {
     ok(false, "Got an error: " + aError.message + "\n" + aError.stack);
     finish();
   });
diff --git a/devtools/client/framework/test/browser_toolbox_view_source_04.js b/devtools/client/framework/test/browser_toolbox_view_source_04.js
index 669703c916b5..47d86fc11c7e 100644
--- a/devtools/client/framework/test/browser_toolbox_view_source_04.js
+++ b/devtools/client/framework/test/browser_toolbox_view_source_04.js
@@ -9,9 +9,9 @@
 
 var URL = `${URL_ROOT}doc_viewsource.html`;
 
-async function viewSource() {
-  let toolbox = await openNewTabAndToolbox(URL);
-  let win = await openScratchpadWindow();
+function* viewSource() {
+  let toolbox = yield openNewTabAndToolbox(URL);
+  let win = yield openScratchpadWindow();
   let { Scratchpad: scratchpad } = win;
 
   // Brahm's Cello Sonata No.1, Op.38 now in the scratchpad
@@ -19,20 +19,20 @@ async function viewSource() {
   let scratchpadURL = scratchpad.uniqueName;
 
   // Now select another tool for focus
-  await toolbox.selectTool("webconsole");
+  yield toolbox.selectTool("webconsole");
 
-  await toolbox.viewSourceInScratchpad(scratchpadURL, 2);
+  yield toolbox.viewSourceInScratchpad(scratchpadURL, 2);
 
   is(scratchpad.editor.getCursor().line, 2,
     "The correct line is highlighted in scratchpad's editor.");
 
   win.close();
-  await closeToolboxAndTab(toolbox);
+  yield closeToolboxAndTab(toolbox);
   finish();
 }
 
 function test() {
-  viewSource().then(finish, (aError) => {
+  Task.spawn(viewSource).then(finish, (aError) => {
     ok(false, "Got an error: " + aError.message + "\n" + aError.stack);
     finish();
   });
diff --git a/devtools/client/framework/test/browser_toolbox_window_title_frame_select.js b/devtools/client/framework/test/browser_toolbox_window_title_frame_select.js
index 9572f66653fb..7994632ad70e 100644
--- a/devtools/client/framework/test/browser_toolbox_window_title_frame_select.js
+++ b/devtools/client/framework/test/browser_toolbox_window_title_frame_select.js
@@ -19,39 +19,39 @@ const IFRAME_URL = URL_ROOT + "browser_toolbox_window_title_changes_page.html";
 const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setBoolPref("devtools.command-button-frames.enabled", true);
 
-  await addTab(URL);
+  yield addTab(URL);
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, null,
+  let toolbox = yield gDevTools.showToolbox(target, null,
     Toolbox.HostType.BOTTOM);
 
   let onTitleChanged = waitForTitleChange(toolbox);
-  await toolbox.selectTool("inspector");
-  await onTitleChanged;
+  yield toolbox.selectTool("inspector");
+  yield onTitleChanged;
 
-  await toolbox.switchHost(Toolbox.HostType.WINDOW);
+  yield toolbox.switchHost(Toolbox.HostType.WINDOW);
   // Wait for title change event *after* switch host, in order to listen
   // for the event on the WINDOW host window, which only exists after switchHost
-  await waitForTitleChange(toolbox);
+  yield waitForTitleChange(toolbox);
 
   is(getTitle(), `Developer Tools - Page title - ${URL}`,
     "Devtools title correct after switching to detached window host");
 
   // Wait for tick to avoid unexpected 'popuphidden' event, which
   // blocks the frame popup menu opened below. See also bug 1276873
-  await waitForTick();
+  yield waitForTick();
 
   let btn = toolbox.doc.getElementById("command-button-frames");
 
-  await testShortcutToOpenFrames(btn, toolbox);
+  yield testShortcutToOpenFrames(btn, toolbox);
 
   // Open frame menu and wait till it's available on the screen.
   // Also check 'open' attribute on the command button.
   ok(!btn.classList.contains("checked"), "The checked class must not be present");
-  let menu = await toolbox.showFramesMenu({target: btn});
-  await once(menu, "open");
+  let menu = yield toolbox.showFramesMenu({target: btn});
+  yield once(menu, "open");
 
   ok(btn.classList.contains("checked"), "The checked class must be set");
 
@@ -75,16 +75,16 @@ add_task(async function () {
   info("Select the iframe");
   iframeBtn.click();
 
-  await willNavigate;
-  await newRoot;
-  await onTitleChanged;
+  yield willNavigate;
+  yield newRoot;
+  yield onTitleChanged;
 
   info("Navigation to the iframe is done, the inspector should be back up");
   is(getTitle(), `Developer Tools - Page title - ${URL}`,
     "Devtools title was not updated after changing inspected frame");
 
   info("Cleanup toolbox and test preferences.");
-  await toolbox.destroy();
+  yield toolbox.destroy();
   toolbox = null;
   gBrowser.removeCurrentTab();
   Services.prefs.clearUserPref("devtools.toolbox.host");
@@ -98,7 +98,7 @@ function getTitle() {
   return Services.wm.getMostRecentWindow("devtools:toolbox").document.title;
 }
 
-async function testShortcutToOpenFrames(btn, toolbox) {
+function* testShortcutToOpenFrames(btn, toolbox) {
   info("Tests if shortcut Alt+Down opens the frames");
   // focus the button so that keyPress can be performed
   btn.focus();
@@ -107,14 +107,14 @@ async function testShortcutToOpenFrames(btn, toolbox) {
   synthesizeKeyShortcut(shortcut, toolbox.win);
 
   // wait for 200 ms for UI to render
-  await wait(200);
+  yield wait(200);
 
   // btn should now have the checked class set
   ok(btn.classList.contains("checked"), "The checked class must be set");
 
   // pressing Esc should hide the menu again
   synthesizeKeyShortcut("Esc", toolbox.win);
-  await wait(200);
+  yield wait(200);
 
   // btn shouldn't have the checked class set
   ok(!btn.classList.contains("checked"), "The checked class must not be set");
diff --git a/devtools/client/framework/test/head.js b/devtools/client/framework/test/head.js
index 4a80243bd9b7..9f66e6204484 100644
--- a/devtools/client/framework/test/head.js
+++ b/devtools/client/framework/test/head.js
@@ -55,11 +55,11 @@ function getSourceActor(aSources, aURL) {
  * @return nsIDOMWindow
  *         The new window object that holds Scratchpad.
  */
-async function openScratchpadWindow() {
+function* openScratchpadWindow() {
   let { promise: p, resolve } = defer();
   let win = ScratchpadManager.openScratchpad();
 
-  await once(win, "load");
+  yield once(win, "load");
 
   win.Scratchpad.addObserver({
     onReady: function () {
diff --git a/devtools/client/framework/test/helper_disable_cache.js b/devtools/client/framework/test/helper_disable_cache.js
index 0818e3b943f2..54fc12afc944 100644
--- a/devtools/client/framework/test/helper_disable_cache.js
+++ b/devtools/client/framework/test/helper_disable_cache.js
@@ -29,36 +29,36 @@ var tabs = [
     startToolbox: false
   }];
 
-async function initTab(tabX, startToolbox) {
-  tabX.tab = await addTab(TEST_URI);
+function* initTab(tabX, startToolbox) {
+  tabX.tab = yield addTab(TEST_URI);
   tabX.target = TargetFactory.forTab(tabX.tab);
 
   if (startToolbox) {
-    tabX.toolbox = await gDevTools.showToolbox(tabX.target, "options");
+    tabX.toolbox = yield gDevTools.showToolbox(tabX.target, "options");
   }
 }
 
-async function checkCacheStateForAllTabs(states) {
+function* checkCacheStateForAllTabs(states) {
   for (let i = 0; i < tabs.length; i++) {
     let tab = tabs[i];
-    await checkCacheEnabled(tab, states[i]);
+    yield checkCacheEnabled(tab, states[i]);
   }
 }
 
-async function checkCacheEnabled(tabX, expected) {
+function* checkCacheEnabled(tabX, expected) {
   gBrowser.selectedTab = tabX.tab;
 
-  await reloadTab(tabX);
+  yield reloadTab(tabX);
 
-  let oldGuid = await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  let oldGuid = yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     let doc = content.document;
     let h1 = doc.querySelector("h1");
     return h1.textContent;
   });
 
-  await reloadTab(tabX);
+  yield reloadTab(tabX);
 
-  let guid = await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  let guid = yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     let doc = content.document;
     let h1 = doc.querySelector("h1");
     return h1.textContent;
@@ -71,7 +71,7 @@ async function checkCacheEnabled(tabX, expected) {
   }
 }
 
-async function setDisableCacheCheckboxChecked(tabX, state) {
+function* setDisableCacheCheckboxChecked(tabX, state) {
   gBrowser.selectedTab = tabX.tab;
 
   let panel = tabX.toolbox.getCurrentPanel();
@@ -83,7 +83,7 @@ async function setDisableCacheCheckboxChecked(tabX, state) {
 
     // We need to wait for all checkboxes to be updated and the docshells to
     // apply the new cache settings.
-    await waitForTick();
+    yield waitForTick();
   }
 }
 
@@ -103,7 +103,7 @@ function reloadTab(tabX) {
   return def.promise;
 }
 
-async function destroyTab(tabX) {
+function* destroyTab(tabX) {
   let toolbox = gDevTools.getToolbox(tabX.target);
 
   let onceDestroyed = promise.resolve();
@@ -116,12 +116,12 @@ async function destroyTab(tabX) {
   info("Removed tab " + tabX.title);
 
   info("Waiting for toolbox-destroyed");
-  await onceDestroyed;
+  yield onceDestroyed;
 }
 
-async function finishUp() {
+function* finishUp() {
   for (let tab of tabs) {
-    await destroyTab(tab);
+    yield destroyTab(tab);
   }
 
   tabs = null;
diff --git a/devtools/client/framework/test/test_browser_toolbox_debugger.js b/devtools/client/framework/test/test_browser_toolbox_debugger.js
index de063c7b5c7a..d6fa794f4f6d 100644
--- a/devtools/client/framework/test/test_browser_toolbox_debugger.js
+++ b/devtools/client/framework/test/test_browser_toolbox_debugger.js
@@ -2,17 +2,17 @@
 
 info(`START: ${new Error().lineNumber}`);
 
-(async function () {
+Task.spawn(function* () {
   Services.prefs.clearUserPref("devtools.debugger.tabs")
   Services.prefs.clearUserPref("devtools.debugger.pending-selected-location")
 
   info("Waiting for debugger load");
-  await toolbox.selectTool("jsdebugger");
+  yield toolbox.selectTool("jsdebugger");
   let dbg = createDebuggerContext(toolbox);
   let window = dbg.win;
   let document = window.document;
 
-  await waitForSources(dbg, testUrl);
+  yield waitForSources(dbg, testUrl);
 //  yield waitForSourceCount(dbg, 6);
 
   info("Loaded, selecting the test script to debug");
@@ -32,23 +32,23 @@ info(`START: ${new Error().lineNumber}`);
   script.click();
 
   let onPaused = waitForPaused(dbg);
-  await addBreakpoint(dbg, fileName, 2);
+  yield addBreakpoint(dbg, fileName, 2);
 
-  await onPaused;
+  yield onPaused;
 
   assertPausedLocation(dbg, fileName, 2);
 
-  await stepIn(dbg);
+  yield stepIn(dbg);
 
   assertPausedLocation(dbg, fileName, 3);
 
   // Remove the breakpoint before resuming in order to prevent hitting the breakpoint
   // again during test closing.
   let source = findSource(dbg, fileName);
-  await removeBreakpoint(dbg, source.id, 2);
+  yield removeBreakpoint(dbg, source.id, 2);
 
-  await resume(dbg);
+  yield resume(dbg);
 
   info("Close the browser toolbox");
   toolbox.destroy();
-})();
+});
diff --git a/devtools/client/framework/toolbox-highlighter-utils.js b/devtools/client/framework/toolbox-highlighter-utils.js
index bb21baaf1bba..a9c644c929b5 100644
--- a/devtools/client/framework/toolbox-highlighter-utils.js
+++ b/devtools/client/framework/toolbox-highlighter-utils.js
@@ -5,6 +5,7 @@
 "use strict";
 
 const promise = require("promise");
+const {Task} = require("devtools/shared/task");
 const flags = require("devtools/shared/flags");
 
 /**
@@ -78,13 +79,13 @@ exports.getHighlighterUtils = function (toolbox) {
    */
   let isInspectorInitialized = false;
   let requireInspector = generator => {
-    return async function (...args) {
+    return Task.async(function* (...args) {
       if (!isInspectorInitialized) {
-        await toolbox.initInspector();
+        yield toolbox.initInspector();
         isInspectorInitialized = true;
       }
-      return generator.apply(null, args);
-    };
+      return yield generator.apply(null, args);
+    });
   };
 
   /**
@@ -111,34 +112,33 @@ exports.getHighlighterUtils = function (toolbox) {
    * @return A promise that resolves when the picker has started or immediately
    * if it is already started
    */
-  let startPicker = exported.startPicker =
-    requireInspector(async function (doFocus = false) {
-      if (isPicking) {
-        return;
-      }
-      isPicking = true;
+  let startPicker = exported.startPicker = requireInspector(function* (doFocus = false) {
+    if (isPicking) {
+      return;
+    }
+    isPicking = true;
 
-      toolbox.pickerButton.isChecked = true;
-      await toolbox.selectTool("inspector");
-      toolbox.on("select", cancelPicker);
+    toolbox.pickerButton.isChecked = true;
+    yield toolbox.selectTool("inspector");
+    toolbox.on("select", cancelPicker);
 
-      if (isRemoteHighlightable()) {
-        toolbox.walker.on("picker-node-hovered", onPickerNodeHovered);
-        toolbox.walker.on("picker-node-picked", onPickerNodePicked);
-        toolbox.walker.on("picker-node-previewed", onPickerNodePreviewed);
-        toolbox.walker.on("picker-node-canceled", onPickerNodeCanceled);
+    if (isRemoteHighlightable()) {
+      toolbox.walker.on("picker-node-hovered", onPickerNodeHovered);
+      toolbox.walker.on("picker-node-picked", onPickerNodePicked);
+      toolbox.walker.on("picker-node-previewed", onPickerNodePreviewed);
+      toolbox.walker.on("picker-node-canceled", onPickerNodeCanceled);
 
-        await toolbox.highlighter.pick(doFocus);
-        toolbox.emit("picker-started");
-      } else {
-        // If the target doesn't have the highlighter actor, we can use the
-        // walker's pick method instead, knowing that it only responds when a node
-        // is picked (instead of emitting events)
-        toolbox.emit("picker-started");
-        let node = await toolbox.walker.pick();
-        onPickerNodePicked({node: node});
-      }
-    });
+      yield toolbox.highlighter.pick(doFocus);
+      toolbox.emit("picker-started");
+    } else {
+      // If the target doesn't have the highlighter actor, we can use the
+      // walker's pick method instead, knowing that it only responds when a node
+      // is picked (instead of emitting events)
+      toolbox.emit("picker-started");
+      let node = yield toolbox.walker.pick();
+      onPickerNodePicked({node: node});
+    }
+  });
 
   /**
    * Stop the element picker. Note that the picker is automatically stopped when
@@ -146,7 +146,7 @@ exports.getHighlighterUtils = function (toolbox) {
    * @return A promise that resolves when the picker has stopped or immediately
    * if it is already stopped
    */
-  let stopPicker = exported.stopPicker = requireInspector(async function () {
+  let stopPicker = exported.stopPicker = requireInspector(function* () {
     if (!isPicking) {
       return;
     }
@@ -155,7 +155,7 @@ exports.getHighlighterUtils = function (toolbox) {
     toolbox.pickerButton.isChecked = false;
 
     if (isRemoteHighlightable()) {
-      await toolbox.highlighter.cancelPick();
+      yield toolbox.highlighter.cancelPick();
       toolbox.walker.off("picker-node-hovered", onPickerNodeHovered);
       toolbox.walker.off("picker-node-picked", onPickerNodePicked);
       toolbox.walker.off("picker-node-previewed", onPickerNodePreviewed);
@@ -163,7 +163,7 @@ exports.getHighlighterUtils = function (toolbox) {
     } else {
       // If the target doesn't have the highlighter actor, use the walker's
       // cancelPick method instead
-      await toolbox.walker.cancelPick();
+      yield toolbox.walker.cancelPick();
     }
 
     toolbox.off("select", cancelPicker);
@@ -173,10 +173,10 @@ exports.getHighlighterUtils = function (toolbox) {
   /**
    * Stop the picker, but also emit an event that the picker was canceled.
    */
-  let cancelPicker = exported.cancelPicker = async function () {
-    await stopPicker();
+  let cancelPicker = exported.cancelPicker = Task.async(function* () {
+    yield stopPicker();
     toolbox.emit("picker-canceled");
-  };
+  });
 
   /**
    * When a node is hovered by the mouse when the highlighter is in picker mode
@@ -222,18 +222,18 @@ exports.getHighlighterUtils = function (toolbox) {
    * @return A promise that resolves when the node has been highlighted
    */
   let highlightNodeFront = exported.highlightNodeFront = requireInspector(
-  async function (nodeFront, options = {}) {
+  function* (nodeFront, options = {}) {
     if (!nodeFront) {
       return;
     }
 
     isNodeFrontHighlighted = true;
     if (isRemoteHighlightable()) {
-      await toolbox.highlighter.showBoxModel(nodeFront, options);
+      yield toolbox.highlighter.showBoxModel(nodeFront, options);
     } else {
       // If the target doesn't have the highlighter actor, revert to the
       // walker's highlight method, which draws a simple outline
-      await toolbox.walker.highlight(nodeFront);
+      yield toolbox.walker.highlight(nodeFront);
     }
 
     toolbox.emit("node-highlight", nodeFront);
@@ -246,15 +246,14 @@ exports.getHighlighterUtils = function (toolbox) {
    * highlightNodeFront, so it has the same signature.
    * @see highlightNodeFront
    */
-  exported.highlightDomValueGrip =
-    requireInspector(async function (valueGrip, options = {}) {
-      let nodeFront = await gripToNodeFront(valueGrip);
-      if (nodeFront) {
-        await highlightNodeFront(nodeFront, options);
-      } else {
-        throw new Error("The ValueGrip passed could not be translated to a NodeFront");
-      }
-    });
+  exported.highlightDomValueGrip = requireInspector(function* (valueGrip, options = {}) {
+    let nodeFront = yield gripToNodeFront(valueGrip);
+    if (nodeFront) {
+      yield highlightNodeFront(nodeFront, options);
+    } else {
+      throw new Error("The ValueGrip passed could not be translated to a NodeFront");
+    }
+  });
 
   /**
    * Translate a debugger value grip into a node front usable by the inspector
@@ -262,8 +261,8 @@ exports.getHighlighterUtils = function (toolbox) {
    * @return a promise that resolves to the node front when done
    */
   let gripToNodeFront = exported.gripToNodeFront = requireInspector(
-  async function (grip) {
-    return toolbox.walker.getNodeActorFromObjectActor(grip.actor);
+  function* (grip) {
+    return yield toolbox.walker.getNodeActorFromObjectActor(grip.actor);
   });
 
   /**
@@ -275,7 +274,7 @@ exports.getHighlighterUtils = function (toolbox) {
    * markup view, which is when this param is passed to true
    * @return a promise that resolves when the highlighter is hidden
    */
-  exported.unhighlight = async function (forceHide = false) {
+  exported.unhighlight = Task.async(function* (forceHide = false) {
     forceHide = forceHide || !flags.testing;
 
     // Note that if isRemoteHighlightable is true, there's no need to hide the
@@ -283,7 +282,7 @@ exports.getHighlighterUtils = function (toolbox) {
     if (isNodeFrontHighlighted && forceHide && toolbox.highlighter &&
         isRemoteHighlightable()) {
       isNodeFrontHighlighted = false;
-      await toolbox.highlighter.hideBoxModel();
+      yield toolbox.highlighter.hideBoxModel();
     }
 
     // unhighlight is called when destroying the toolbox, which means that by
@@ -291,7 +290,7 @@ exports.getHighlighterUtils = function (toolbox) {
     if (toolbox) {
       toolbox.emit("node-unhighlight");
     }
-  };
+  });
 
   /**
    * If the main, box-model, highlighter isn't enough, or if multiple
@@ -302,11 +301,11 @@ exports.getHighlighterUtils = function (toolbox) {
    * methods and needs to be released by the consumer when not needed anymore.
    * @return a promise that resolves to the highlighter
    */
-  exported.getHighlighterByType = requireInspector(async function (typeName) {
+  exported.getHighlighterByType = requireInspector(function* (typeName) {
     let highlighter = null;
 
     if (supportsCustomHighlighters()) {
-      highlighter = await toolbox.inspector.getHighlighterByType(typeName);
+      highlighter = yield toolbox.inspector.getHighlighterByType(typeName);
     }
 
     return highlighter || promise.reject("The target doesn't support " +
diff --git a/devtools/client/framework/toolbox-host-manager.js b/devtools/client/framework/toolbox-host-manager.js
index 080a6e55cf53..93021c84e7ae 100644
--- a/devtools/client/framework/toolbox-host-manager.js
+++ b/devtools/client/framework/toolbox-host-manager.js
@@ -8,6 +8,7 @@ const Services = require("Services");
 const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");
 const DevToolsUtils = require("devtools/shared/DevToolsUtils");
+const {Task} = require("devtools/shared/task");
 
 loader.lazyRequireGetter(this, "Toolbox", "devtools/client/framework/toolbox", true);
 loader.lazyRequireGetter(this, "Hosts", "devtools/client/framework/toolbox-hosts", true);
@@ -63,8 +64,8 @@ function ToolboxHostManager(target, hostType, hostOptions) {
 }
 
 ToolboxHostManager.prototype = {
-  async create(toolId) {
-    await this.host.create();
+  create: Task.async(function* (toolId) {
+    yield this.host.create();
 
     this.host.frame.setAttribute("aria-label", L10N.getStr("toolbox.label"));
     this.host.frame.ownerDocument.defaultView.addEventListener("message", this);
@@ -82,7 +83,7 @@ ToolboxHostManager.prototype = {
     }
 
     return toolbox;
-  },
+  }),
 
   handleEvent(event) {
     switch (event.type) {
@@ -185,7 +186,7 @@ ToolboxHostManager.prototype = {
     });
   },
 
-  async switchHost(hostType) {
+  switchHost: Task.async(function* (hostType) {
     if (hostType == "previous") {
       // Switch to the last used host for the toolbox UI.
       // This is determined by the devtools.toolbox.previousHost pref.
@@ -203,7 +204,7 @@ ToolboxHostManager.prototype = {
     }
     let iframe = this.host.frame;
     let newHost = this.createHost(hostType);
-    let newIframe = await newHost.create();
+    let newIframe = yield newHost.create();
     // change toolbox document's parent to the new host
     newIframe.swapFrameLoaders(iframe);
 
@@ -228,7 +229,7 @@ ToolboxHostManager.prototype = {
       name: "switched-host",
       hostType
     });
-  },
+  }),
 
   /**
    * Destroy the current host, and remove event listeners from its frame.
diff --git a/devtools/client/framework/toolbox-init.js b/devtools/client/framework/toolbox-init.js
index b7ca729515fb..7ae0e8b3ebe1 100644
--- a/devtools/client/framework/toolbox-init.js
+++ b/devtools/client/framework/toolbox-init.js
@@ -20,6 +20,7 @@ if (url.search.length > 1) {
   const { TargetFactory } = require("devtools/client/framework/target");
   const { DebuggerServer } = require("devtools/server/main");
   const { DebuggerClient } = require("devtools/shared/client/debugger-client");
+  const { Task } = require("devtools/shared/task");
 
   // `host` is the frame element loading the toolbox.
   let host = window.QueryInterface(Ci.nsIInterfaceRequestor)
@@ -46,7 +47,7 @@ if (url.search.length > 1) {
   // Specify the default tool to open
   let tool = url.searchParams.get("tool");
 
-  (async function () {
+  Task.spawn(function* () {
     let target;
     if (url.searchParams.has("target")) {
       // Attach toolbox to a given browser iframe (<xul:browser> or <html:iframe
@@ -71,17 +72,17 @@ if (url.search.length > 1) {
       DebuggerServer.registerAllActors();
       let client = new DebuggerClient(DebuggerServer.connectPipe());
 
-      await client.connect();
+      yield client.connect();
       // Creates a target for a given browser iframe.
-      let response = await client.getTab({ tab });
+      let response = yield client.getTab({ tab });
       let form = response.tab;
-      target = await TargetFactory.forRemoteTab({client, form, chrome: false});
+      target = yield TargetFactory.forRemoteTab({client, form, chrome: false});
     } else {
-      target = await targetFromURL(url);
+      target = yield targetFromURL(url);
     }
     let options = { customIframe: host };
-    await gDevTools.showToolbox(target, tool, Toolbox.HostType.CUSTOM, options);
-  })().catch(error => {
+    yield gDevTools.showToolbox(target, tool, Toolbox.HostType.CUSTOM, options);
+  }).catch(error => {
     console.error("Exception while loading the toolbox", error);
   });
 }
diff --git a/devtools/client/framework/toolbox-options.js b/devtools/client/framework/toolbox-options.js
index 01e8d6aeed6d..05c47dba9435 100644
--- a/devtools/client/framework/toolbox-options.js
+++ b/devtools/client/framework/toolbox-options.js
@@ -6,6 +6,7 @@
 
 const Services = require("Services");
 const defer = require("devtools/shared/defer");
+const {Task} = require("devtools/shared/task");
 const {gDevTools} = require("devtools/client/framework/devtools");
 
 const {LocalizationHelper} = require("devtools/shared/l10n");
@@ -80,21 +81,21 @@ OptionsPanel.prototype = {
     return this.toolbox.target;
   },
 
-  async open() {
+  open: Task.async(function* () {
     // For local debugging we need to make the target remote.
     if (!this.target.isRemote) {
-      await this.target.makeRemote();
+      yield this.target.makeRemote();
     }
 
     this.setupToolsList();
     this.setupToolbarButtonsList();
     this.setupThemeList();
     this.setupNightlyOptions();
-    await this.populatePreferences();
+    yield this.populatePreferences();
     this.isReady = true;
     this.emit("ready");
     return this;
-  },
+  }),
 
   _addListeners: function () {
     Services.prefs.addObserver("devtools.cache.disabled", this._prefChanged);
@@ -139,9 +140,9 @@ OptionsPanel.prototype = {
     }
   },
 
-  async setupToolbarButtonsList() {
+  setupToolbarButtonsList: Task.async(function* () {
     // Ensure the toolbox is open, and the buttons are all set up.
-    await this.toolbox.isOpen;
+    yield this.toolbox.isOpen;
 
     let enabledToolbarButtonsBox = this.panelDoc.getElementById(
       "enabled-toolbox-buttons-box");
@@ -186,7 +187,7 @@ OptionsPanel.prototype = {
 
       enabledToolbarButtonsBox.appendChild(createCommandCheckbox(button));
     }
-  },
+  }),
 
   setupToolsList: function () {
     let defaultToolsBox = this.panelDoc.getElementById("default-tools-box");
@@ -361,7 +362,7 @@ OptionsPanel.prototype = {
     }
   },
 
-  async populatePreferences() {
+  populatePreferences: Task.async(function* () {
     let prefCheckboxes = this.panelDoc.querySelectorAll(
       "input[type=checkbox][data-pref]");
     for (let prefCheckbox of prefCheckboxes) {
@@ -412,7 +413,7 @@ OptionsPanel.prototype = {
     }
 
     if (this.target.activeTab) {
-      let [ response ] = await this.target.client.attachTab(this.target.activeTab._actor);
+      let [ response ] = yield this.target.client.attachTab(this.target.activeTab._actor);
       this._origJavascriptEnabled = !response.javascriptEnabled;
       this.disableJSNode.checked = this._origJavascriptEnabled;
       this.disableJSNode.addEventListener("click", this._disableJSClicked);
@@ -420,7 +421,7 @@ OptionsPanel.prototype = {
       // Hide the checkbox and label
       this.disableJSNode.parentNode.style.display = "none";
     }
-  },
+  }),
 
   updateCurrentTheme: function () {
     let currentTheme = GetPref("devtools.theme");
diff --git a/devtools/client/framework/toolbox.js b/devtools/client/framework/toolbox.js
index f80a55a78914..8e76cda30ead 100644
--- a/devtools/client/framework/toolbox.js
+++ b/devtools/client/framework/toolbox.js
@@ -20,6 +20,7 @@ var promise = require("promise");
 var defer = require("devtools/shared/defer");
 var Services = require("Services");
 var ChromeUtils = require("ChromeUtils");
+var {Task} = require("devtools/shared/task");
 var {gDevTools} = require("devtools/client/framework/devtools");
 var EventEmitter = require("devtools/shared/old-event-emitter");
 var Telemetry = require("devtools/client/shared/telemetry");
@@ -425,7 +426,7 @@ Toolbox.prototype = {
    * Open the toolbox
    */
   open: function () {
-    return (async function () {
+    return Task.spawn(function* () {
       this.browserRequire = BrowserLoader({
         window: this.doc.defaultView,
         useOnlyShared: true
@@ -446,19 +447,19 @@ Toolbox.prototype = {
       // the iframe being ready (makes startup faster)
 
       // Load the toolbox-level actor fronts and utilities now
-      await this._target.makeRemote();
+      yield this._target.makeRemote();
 
       // Start tracking network activity on toolbox open for targets such as tabs.
       // (Workers and potentially others don't manage the console client in the target.)
       if (this._target.activeConsole) {
-        await this._target.activeConsole.startListeners([
+        yield this._target.activeConsole.startListeners([
           "NetworkActivity",
         ]);
       }
 
       // Attach the thread
-      this._threadClient = await attachThread(this);
-      await domReady.promise;
+      this._threadClient = yield attachThread(this);
+      yield domReady.promise;
 
       this.isReady = true;
 
@@ -537,7 +538,7 @@ Toolbox.prototype = {
         }, {timeout: 16});
       });
 
-      await this.selectTool(this._defaultToolId);
+      yield this.selectTool(this._defaultToolId);
 
       // Wait until the original tool is selected so that the split
       // console input will receive focus.
@@ -546,7 +547,7 @@ Toolbox.prototype = {
         splitConsolePromise = this.openSplitConsole();
       }
 
-      await promise.all([
+      yield promise.all([
         splitConsolePromise,
         buttonsPromise,
         framesPromise
@@ -560,12 +561,12 @@ Toolbox.prototype = {
       // so we don't have to explicitly wait for this in tests; ideally, all tests
       // will handle this on their own, but each have their own tear down function.
       if (flags.testing) {
-        await performanceFrontConnection;
+        yield performanceFrontConnection;
       }
 
       this.emit("ready");
       this._isOpenDeferred.resolve();
-    }.bind(this))().catch(console.error.bind(console));
+    }.bind(this)).catch(console.error.bind(console));
   },
 
   /**
@@ -1257,12 +1258,12 @@ Toolbox.prototype = {
   /**
    * Add buttons to the UI as specified in devtools/client/definitions.js
    */
-  async _buildButtons() {
+  _buildButtons: Task.async(function* () {
     // Beyond the normal preference filtering
     this.toolbarButtons = [
       this._buildPickerButton(),
       this._buildFrameButton(),
-      await this._buildNoAutoHideButton()
+      yield this._buildNoAutoHideButton()
     ];
 
     ToolboxButtons.forEach(definition => {
@@ -1271,7 +1272,7 @@ Toolbox.prototype = {
     });
 
     this.component.setToolboxButtons(this.toolbarButtons);
-  },
+  }),
 
   /**
    * Button to select a frame for the inspector to target.
@@ -1294,7 +1295,7 @@ Toolbox.prototype = {
    * Button that disables/enables auto-hiding XUL pop-ups. When enabled, XUL
    * pop-ups will not automatically close when they lose focus.
    */
-  async _buildNoAutoHideButton() {
+  _buildNoAutoHideButton: Task.async(function* () {
     this.autohideButton = this._createButtonState({
       id: "command-button-noautohide",
       description: L10N.getStr("toolbox.noautohide.tooltip"),
@@ -1307,7 +1308,7 @@ Toolbox.prototype = {
     });
 
     return this.autohideButton;
-  },
+  }),
 
   /**
    * Toggle the picker, but also decide whether or not the highlighter should
@@ -2065,12 +2066,12 @@ Toolbox.prototype = {
    * @param {string} id
    *        The id of the tool to highlight
    */
-  async highlightTool(id) {
+  highlightTool: Task.async(function* (id) {
     if (!this.component) {
-      await this.isOpen;
+      yield this.isOpen;
     }
     this.component.highlightTool(id);
-  },
+  }),
 
   /**
    * De-highlights the tool's tab.
@@ -2078,12 +2079,12 @@ Toolbox.prototype = {
    * @param {string} id
    *        The id of the tool to unhighlight
    */
-  async unhighlightTool(id) {
+  unhighlightTool: Task.async(function* (id) {
     if (!this.component) {
-      await this.isOpen;
+      yield this.isOpen;
     }
     this.component.unhighlightTool(id);
-  },
+  }),
 
   /**
    * Raise the toolbox host.
@@ -2151,26 +2152,26 @@ Toolbox.prototype = {
     });
   },
 
-  async _toggleNoAutohide() {
-    let front = await this.preferenceFront;
-    let toggledValue = !(await this._isDisableAutohideEnabled());
+  _toggleNoAutohide: Task.async(function* () {
+    let front = yield this.preferenceFront;
+    let toggledValue = !(yield this._isDisableAutohideEnabled());
 
     front.setBoolPref(DISABLE_AUTOHIDE_PREF, toggledValue);
 
     this.autohideButton.isChecked = toggledValue;
     this._autohideHasBeenToggled = true;
-  },
+  }),
 
-  async _isDisableAutohideEnabled() {
+  _isDisableAutohideEnabled: Task.async(function* () {
     // Ensure that the tools are open, and the button is visible.
-    await this.isOpen;
+    yield this.isOpen;
     if (!this.autohideButton.isVisible) {
       return false;
     }
 
-    let prefFront = await this.preferenceFront;
-    return prefFront.getBoolPref(DISABLE_AUTOHIDE_PREF);
-  },
+    let prefFront = yield this.preferenceFront;
+    return yield prefFront.getBoolPref(DISABLE_AUTOHIDE_PREF);
+  }),
 
   _listFrames: function (event) {
     if (!this._target.activeTab || !this._target.activeTab.traits.frames) {
@@ -2552,11 +2553,11 @@ Toolbox.prototype = {
    */
   initInspector: function () {
     if (!this._initInspector) {
-      this._initInspector = (async function () {
+      this._initInspector = Task.spawn(function* () {
         this._inspector = InspectorFront(this._target.client, this._target.form);
         let pref = "devtools.inspector.showAllAnonymousContent";
         let showAllAnonymousContent = Services.prefs.getBoolPref(pref);
-        this._walker = await this._inspector.getWalker({ showAllAnonymousContent });
+        this._walker = yield this._inspector.getWalker({ showAllAnonymousContent });
         this._selection = new Selection(this._walker);
         this._selection.on("new-node-front", this._onNewSelectedNodeFront);
 
@@ -2565,9 +2566,9 @@ Toolbox.prototype = {
           this.walker.on("highlighter-hide", this._highlighterHidden);
 
           let autohide = !flags.testing;
-          this._highlighter = await this._inspector.getHighlighter(autohide);
+          this._highlighter = yield this._inspector.getHighlighter(autohide);
         }
-      }.bind(this))();
+      }.bind(this));
     }
     return this._initInspector;
   },
@@ -2615,23 +2616,23 @@ Toolbox.prototype = {
       return this._destroyingInspector;
     }
 
-    this._destroyingInspector = (async function () {
+    this._destroyingInspector = Task.spawn(function* () {
       if (!this._inspector) {
         return;
       }
 
       // Ensure that the inspector isn't still being initiated, otherwise race conditions
       // in the initialization process can throw errors.
-      await this._initInspector;
+      yield this._initInspector;
 
       let currentPanel = this.getCurrentPanel();
       if (currentPanel.stopPicker) {
-        await currentPanel.stopPicker();
+        yield currentPanel.stopPicker();
       } else {
-        await this.highlighterUtils.stopPicker();
+        yield this.highlighterUtils.stopPicker();
       }
 
-      await this._inspector.destroy();
+      yield this._inspector.destroy();
       if (this._highlighter) {
         // Note that if the toolbox is closed, this will work fine, but will fail
         // in case the browser is closed and will trigger a noSuchActor message.
@@ -2641,7 +2642,7 @@ Toolbox.prototype = {
         if (!this.highlighter.traits.autoHideOnDestroy) {
           this.highlighterUtils.unhighlight();
         }
-        await this._highlighter.destroy();
+        yield this._highlighter.destroy();
       }
       if (this._selection) {
         this._selection.off("new-node-front", this._onNewSelectedNodeFront);
@@ -2657,7 +2658,7 @@ Toolbox.prototype = {
       this._highlighter = null;
       this._selection = null;
       this._walker = null;
-    }.bind(this))();
+    }.bind(this));
     return this._destroyingInspector;
   },
 
@@ -2897,7 +2898,7 @@ Toolbox.prototype = {
    * Connects to the Gecko Profiler when the developer tools are open. This is
    * necessary because of the WebConsole's `profile` and `profileEnd` methods.
    */
-  async initPerformance() {
+  initPerformance: Task.async(function* () {
     // If target does not have performance actor (addons), do not
     // even register the shared performance connection.
     if (!this.target.hasActor("performance")) {
@@ -2910,7 +2911,7 @@ Toolbox.prototype = {
 
     this._performanceFrontConnection = defer();
     this._performance = createPerformanceFront(this._target);
-    await this.performance.connect();
+    yield this.performance.connect();
 
     // Emit an event when connected, but don't wait on startup for this.
     this.emit("profiler-connected");
@@ -2918,26 +2919,26 @@ Toolbox.prototype = {
     this.performance.on("*", this._onPerformanceFrontEvent);
     this._performanceFrontConnection.resolve(this.performance);
     return this._performanceFrontConnection.promise;
-  },
+  }),
 
   /**
    * Disconnects the underlying Performance actor. If the connection
    * has not finished initializing, as opening a toolbox does not wait,
    * the performance connection destroy method will wait for it on its own.
    */
-  async destroyPerformance() {
+  destroyPerformance: Task.async(function* () {
     if (!this.performance) {
       return;
     }
     // If still connecting to performance actor, allow the
     // actor to resolve its connection before attempting to destroy.
     if (this._performanceFrontConnection) {
-      await this._performanceFrontConnection.promise;
+      yield this._performanceFrontConnection.promise;
     }
     this.performance.off("*", this._onPerformanceFrontEvent);
-    await this.performance.destroy();
+    yield this.performance.destroy();
     this._performance = null;
-  },
+  }),
 
   /**
    * Return the style sheets front, creating it if necessary.  If the
@@ -2953,7 +2954,7 @@ Toolbox.prototype = {
   /**
    * Destroy the preferences actor when the toolbox is unloaded.
    */
-  async destroyPreference() {
+  destroyPreference: Task.async(function* () {
     if (!this._preferenceFront) {
       return;
     }
@@ -2961,12 +2962,12 @@ Toolbox.prototype = {
     // Only reset the autohide pref in the Browser Toolbox if it's been toggled
     // in the UI (don't reset the pref if it was already set before opening)
     if (this._autohideHasBeenToggled) {
-      await this._preferenceFront.clearUserPref(DISABLE_AUTOHIDE_PREF);
+      yield this._preferenceFront.clearUserPref(DISABLE_AUTOHIDE_PREF);
     }
 
     this._preferenceFront.destroy();
     this._preferenceFront = null;
-  },
+  }),
 
   /**
    * Called when any event comes from the PerformanceFront. If the performance tool is
@@ -2975,7 +2976,7 @@ Toolbox.prototype = {
    * handle them, which will only occur when `console.profile()` recordings are started
    * before the tool loads.
    */
-  async _onPerformanceFrontEvent(eventName, recording) {
+  _onPerformanceFrontEvent: Task.async(function* (eventName, recording) {
     if (this.getPanel("performance")) {
       this.performance.off("*", this._onPerformanceFrontEvent);
       return;
@@ -2990,8 +2991,8 @@ Toolbox.prototype = {
     // observed during that time.
     if (eventName === "console-profile-start" && !this._performanceToolOpenedViaConsole) {
       this._performanceToolOpenedViaConsole = this.loadTool("performance");
-      let panel = await this._performanceToolOpenedViaConsole;
-      await panel.open();
+      let panel = yield this._performanceToolOpenedViaConsole;
+      yield panel.open();
 
       panel.panelWin.PerformanceController.populateWithRecordings(recordings);
       this.performance.off("*", this._onPerformanceFrontEvent);
@@ -3003,7 +3004,7 @@ Toolbox.prototype = {
     if (eventName === "recording-started") {
       recordings.push(recording);
     }
-  },
+  }),
 
   /**
    * Returns gViewSourceUtils for viewing source.
diff --git a/devtools/client/inspector/test/shared-head.js b/devtools/client/inspector/test/shared-head.js
index 0a0359c3699b..99c0864cac21 100644
--- a/devtools/client/inspector/test/shared-head.js
+++ b/devtools/client/inspector/test/shared-head.js
@@ -5,11 +5,9 @@
 "use strict";
 
 /* eslint no-unused-vars: [2, {"vars": "local"}] */
-/* globals registerTestActor, getTestActor, openToolboxForTab, gBrowser */
+/* globals registerTestActor, getTestActor, Task, openToolboxForTab, gBrowser */
 /* import-globals-from ../../shared/test/shared-head.js */
 
-const { Task } = require("devtools/shared/task");
-
 var {getInplaceEditorForSpan: inplaceEditor} = require("devtools/client/shared/inplace-editor");
 
 // This file contains functions related to the inspector that are also of interest to
diff --git a/devtools/client/jsonview/test/browser_json_refresh.js b/devtools/client/jsonview/test/browser_json_refresh.js
index 12eac98bb83e..a8062f83641a 100644
--- a/devtools/client/jsonview/test/browser_json_refresh.js
+++ b/devtools/client/jsonview/test/browser_json_refresh.js
@@ -7,17 +7,17 @@
 
 const TEST_JSON_FILE = "simple_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test JSON refresh started");
 
   // generate file:// URI for JSON file and load in new tab
   let dir = getChromeDir(getResolvedURI(gTestPath));
   dir.append(TEST_JSON_FILE);
   let uri = Services.io.newFileURI(dir);
-  let tab = await addJsonViewTab(uri.spec);
+  let tab = yield addJsonViewTab(uri.spec);
 
   // perform sanity checks for URI and pricnipals in loadInfo
-  await ContentTask.spawn(tab.linkedBrowser, {TEST_JSON_FILE}, async function ({TEST_JSON_FILE}) { // eslint-disable-line
+  yield ContentTask.spawn(tab.linkedBrowser, {TEST_JSON_FILE}, function*({TEST_JSON_FILE}) { // eslint-disable-line
     let channel = content.document.docShell.currentDocumentChannel;
     let channelURI = channel.URI.spec;
     ok(channelURI.startsWith("file://") && channelURI.includes(TEST_JSON_FILE),
@@ -40,10 +40,10 @@ add_task(async function () {
   // reload the tab
   let loaded = BrowserTestUtils.browserLoaded(tab.linkedBrowser);
   tab.linkedBrowser.reload();
-  await loaded;
+  yield loaded;
 
   // check principals in loadInfo are still correct
-  await ContentTask.spawn(tab.linkedBrowser, {TEST_JSON_FILE}, async function ({TEST_JSON_FILE}) { // eslint-disable-line
+  yield ContentTask.spawn(tab.linkedBrowser, {TEST_JSON_FILE}, function*({TEST_JSON_FILE}) { // eslint-disable-line
     let channel = content.document.docShell.currentDocumentChannel;
     let channelURI = channel.URI.spec;
     ok(channelURI.startsWith("file://") && channelURI.includes(TEST_JSON_FILE),
diff --git a/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js b/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js
index edc2d49a8e79..12a80b6ca416 100644
--- a/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js
+++ b/devtools/client/jsonview/test/browser_jsonview_bug_1380828.js
@@ -7,26 +7,26 @@ const VALID_JSON_URL = URL_ROOT + "valid_json.json";
 const INVALID_JSON_URL = URL_ROOT + "invalid_json.json";
 const prettyPrintButtonClass = ".textPanelBox .toolbar button.prettyprint";
 
-add_task(async function () {
+add_task(function* () {
   info("Test 'Pretty Print' button disappears on parsing invalid JSON");
 
-  let count = await testPrettyPrintButton(INVALID_JSON_URL);
+  let count = yield testPrettyPrintButton(INVALID_JSON_URL);
   is(count, 0, "There must be no pretty-print button for invalid json");
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Test 'Pretty Print' button is present on parsing valid JSON");
 
-  let count = await testPrettyPrintButton(VALID_JSON_URL);
+  let count = yield testPrettyPrintButton(VALID_JSON_URL);
   is(count, 1, "There must be pretty-print button for valid json");
 });
 
-async function testPrettyPrintButton(url) {
-  await addJsonViewTab(url);
+function* testPrettyPrintButton(url) {
+  yield addJsonViewTab(url);
 
-  await selectJsonViewContentTab("rawdata");
+  yield selectJsonViewContentTab("rawdata");
   info("Switched to Raw Data tab.");
 
-  let count = await getElementCount(prettyPrintButtonClass);
+  let count = yield getElementCount(prettyPrintButtonClass);
   return count;
 }
diff --git a/devtools/client/jsonview/test/browser_jsonview_content_type.js b/devtools/client/jsonview/test/browser_jsonview_content_type.js
index 93a7a20067bc..d8d55a9a2204 100644
--- a/devtools/client/jsonview/test/browser_jsonview_content_type.js
+++ b/devtools/client/jsonview/test/browser_jsonview_content_type.js
@@ -26,7 +26,7 @@ let contentTypes = {
   ],
 };
 
-add_task(async function () {
+add_task(function* () {
   info("Test JSON content types started");
 
   // Prevent saving files to disk.
@@ -46,8 +46,8 @@ add_task(async function () {
       mimeInfo.alwaysAskBeforeHandling = false;
       handlerSvc.store(mimeInfo);
 
-      await testType(isValid, type);
-      await testType(isValid, type, ";foo=bar+json");
+      yield testType(isValid, type);
+      yield testType(isValid, type, ";foo=bar+json");
 
       // Restore old nsIMIMEInfo
       if (exists) {
diff --git a/devtools/client/jsonview/test/browser_jsonview_copy_headers.js b/devtools/client/jsonview/test/browser_jsonview_copy_headers.js
index 60a623a87701..1ffe9f8ca9f4 100644
--- a/devtools/client/jsonview/test/browser_jsonview_copy_headers.js
+++ b/devtools/client/jsonview/test/browser_jsonview_copy_headers.js
@@ -7,25 +7,25 @@
 
 const TEST_JSON_URL = URL_ROOT + "valid_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test valid JSON started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
   // Select the RawData tab
-  await selectJsonViewContentTab("headers");
+  yield selectJsonViewContentTab("headers");
 
   // Check displayed headers
-  let count = await getElementCount(".headersPanelBox .netHeadersGroup");
+  let count = yield getElementCount(".headersPanelBox .netHeadersGroup");
   is(count, 2, "There must be two header groups");
 
-  let text = await getElementText(".headersPanelBox .netInfoHeadersTable");
+  let text = yield getElementText(".headersPanelBox .netInfoHeadersTable");
   isnot(text, "", "Headers text must not be empty");
 
   let browser = gBrowser.selectedBrowser;
 
   // Verify JSON copy into the clipboard.
-  await waitForClipboardPromise(function setup() {
+  yield waitForClipboardPromise(function setup() {
     BrowserTestUtils.synthesizeMouseAtCenter(
       ".headersPanelBox .toolbar button.copy",
       {}, browser);
diff --git a/devtools/client/jsonview/test/browser_jsonview_copy_json.js b/devtools/client/jsonview/test/browser_jsonview_copy_json.js
index 0b04e7e9d80f..b4c08b843d3d 100644
--- a/devtools/client/jsonview/test/browser_jsonview_copy_json.js
+++ b/devtools/client/jsonview/test/browser_jsonview_copy_json.js
@@ -7,22 +7,22 @@
 
 const TEST_JSON_URL = URL_ROOT + "simple_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test copy JSON started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let countBefore = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let countBefore = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   ok(countBefore == 1, "There must be one row");
 
-  let text = await getElementText(".jsonPanelBox .treeTable .treeRow");
+  let text = yield getElementText(".jsonPanelBox .treeTable .treeRow");
   is(text, "name\"value\"", "There must be proper JSON displayed");
 
   // Verify JSON copy into the clipboard.
   let value = "{\"name\": \"value\"}\n";
   let browser = gBrowser.selectedBrowser;
   let selector = ".jsonPanelBox .toolbar button.copy";
-  await waitForClipboardPromise(function setup() {
+  yield waitForClipboardPromise(function setup() {
     BrowserTestUtils.synthesizeMouseAtCenter(selector, {}, browser);
   }, function validator(result) {
     let str = normalizeNewLines(result);
diff --git a/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js b/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js
index aee7ce8e554d..d2346ea42256 100644
--- a/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js
+++ b/devtools/client/jsonview/test/browser_jsonview_copy_rawdata.js
@@ -10,39 +10,39 @@ const TEST_JSON_URL = URL_ROOT + "simple_json.json";
 let jsonText = "{\"name\": \"value\"}\n";
 let prettyJson = "{\n  \"name\": \"value\"\n}";
 
-add_task(async function () {
+add_task(function* () {
   info("Test copy raw data started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
   // Select the RawData tab
-  await selectJsonViewContentTab("rawdata");
+  yield selectJsonViewContentTab("rawdata");
 
   // Check displayed JSON
-  let text = await getElementText(".textPanelBox .data");
+  let text = yield getElementText(".textPanelBox .data");
   is(text, jsonText, "Proper JSON must be displayed in DOM");
 
   let browser = gBrowser.selectedBrowser;
 
   // Verify JSON copy into the clipboard.
-  await waitForClipboardPromise(function setup() {
+  yield waitForClipboardPromise(function setup() {
     BrowserTestUtils.synthesizeMouseAtCenter(
       ".textPanelBox .toolbar button.copy",
       {}, browser);
   }, jsonText);
 
   // Click 'Pretty Print' button
-  await BrowserTestUtils.synthesizeMouseAtCenter(
+  yield BrowserTestUtils.synthesizeMouseAtCenter(
     ".textPanelBox .toolbar button.prettyprint",
     {}, browser);
 
-  let prettyText = await getElementText(".textPanelBox .data");
+  let prettyText = yield getElementText(".textPanelBox .data");
   prettyText = normalizeNewLines(prettyText);
   ok(prettyText.startsWith(prettyJson),
     "Pretty printed JSON must be displayed");
 
   // Verify JSON copy into the clipboard.
-  await waitForClipboardPromise(function setup() {
+  yield waitForClipboardPromise(function setup() {
     BrowserTestUtils.synthesizeMouseAtCenter(
       ".textPanelBox .toolbar button.copy",
       {}, browser);
diff --git a/devtools/client/jsonview/test/browser_jsonview_csp_json.js b/devtools/client/jsonview/test/browser_jsonview_csp_json.js
index ddccd5984d60..f7f898ba870e 100644
--- a/devtools/client/jsonview/test/browser_jsonview_csp_json.js
+++ b/devtools/client/jsonview/test/browser_jsonview_csp_json.js
@@ -7,11 +7,11 @@
 
 const TEST_JSON_URL = URL_ROOT + "csp_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test CSP JSON started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let count = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   is(count, 1, "There must be one row");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_empty_object.js b/devtools/client/jsonview/test/browser_jsonview_empty_object.js
index 43bbbb77582e..f4976d5ec6a6 100644
--- a/devtools/client/jsonview/test/browser_jsonview_empty_object.js
+++ b/devtools/client/jsonview/test/browser_jsonview_empty_object.js
@@ -6,37 +6,37 @@
 "use strict";
 
 function testRootObject(objExpr, summary = objExpr) {
-  return async function () {
+  return function* () {
     info("Test JSON with root empty object " + objExpr + " started");
 
     let TEST_JSON_URL = "data:application/json," + objExpr;
-    await addJsonViewTab(TEST_JSON_URL);
+    yield addJsonViewTab(TEST_JSON_URL);
 
-    let objectText = await getElementText(
+    let objectText = yield getElementText(
       ".jsonPanelBox .panelContent");
     is(objectText, summary, "The root object " + objExpr + " is visible");
   };
 }
 
 function testNestedObject(objExpr, summary = objExpr) {
-  return async function () {
+  return function* () {
     info("Test JSON with nested empty object " + objExpr + " started");
 
     let TEST_JSON_URL = "data:application/json,[" + objExpr + "]";
-    await addJsonViewTab(TEST_JSON_URL);
+    yield addJsonViewTab(TEST_JSON_URL);
 
-    let objectCellCount = await getElementCount(
+    let objectCellCount = yield getElementCount(
       ".jsonPanelBox .treeTable .objectCell");
     is(objectCellCount, 1, "There must be one object cell");
 
-    let objectCellText = await getElementText(
+    let objectCellText = yield getElementText(
       ".jsonPanelBox .treeTable .objectCell");
     is(objectCellText, summary, objExpr + " has a visible summary");
 
     // Collapse auto-expanded node.
-    await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+    yield clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
 
-    let textAfter = await getElementText(
+    let textAfter = yield getElementText(
       ".jsonPanelBox .treeTable .objectCell");
     is(textAfter, summary, objExpr + " still has a visible summary");
   };
diff --git a/devtools/client/jsonview/test/browser_jsonview_encoding.js b/devtools/client/jsonview/test/browser_jsonview_encoding.js
index e8d1992188cb..7a0ca487dbfc 100644
--- a/devtools/client/jsonview/test/browser_jsonview_encoding.js
+++ b/devtools/client/jsonview/test/browser_jsonview_encoding.js
@@ -5,7 +5,7 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   info("Test JSON encoding started");
 
   const bom = "%EF%BB%BF"; // UTF-8 BOM
@@ -49,11 +49,11 @@ add_task(async function () {
   for (let {input, output} of tests) {
     info("Test decoding of " + JSON.stringify(input) + ".");
 
-    await addJsonViewTab("data:application/json," + input);
-    await selectJsonViewContentTab("rawdata");
+    yield addJsonViewTab("data:application/json," + input);
+    yield selectJsonViewContentTab("rawdata");
 
     // Check displayed data.
-    let data = await getElementText(".textPanelBox .data");
+    let data = yield getElementText(".textPanelBox .data");
     is(data, output, "The right data has been received.");
   }
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_filter.js b/devtools/client/jsonview/test/browser_jsonview_filter.js
index c1964af9ba0e..5e87bb8aecaa 100644
--- a/devtools/client/jsonview/test/browser_jsonview_filter.js
+++ b/devtools/client/jsonview/test/browser_jsonview_filter.js
@@ -7,22 +7,22 @@
 
 const TEST_JSON_URL = URL_ROOT + "array_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test valid JSON started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let count = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   is(count, 6, "There must be expected number of rows");
 
   // XXX use proper shortcut to focus the filter box
   // as soon as bug Bug 1178771 is fixed.
-  await sendString("h", ".jsonPanelBox .searchBox");
+  yield sendString("h", ".jsonPanelBox .searchBox");
 
   // The filtering is done asynchronously so, we need to wait.
-  await waitForFilter();
+  yield waitForFilter();
 
-  let hiddenCount = await getElementCount(
+  let hiddenCount = yield getElementCount(
     ".jsonPanelBox .treeTable .treeRow.hidden");
   is(hiddenCount, 4, "There must be expected number of hidden rows");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js b/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js
index 9c9076f1f0e6..9ce51314310d 100644
--- a/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js
+++ b/devtools/client/jsonview/test/browser_jsonview_ignore_charset.js
@@ -5,16 +5,16 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   info("Test ignored charset parameter started");
 
   const encodedChar = "%E2%9D%A4"; // In UTF-8 this is a heavy black heart
   const result = "\u2764"; // ❤
   const TEST_JSON_URL = "data:application/json;charset=ANSI," + encodedChar;
 
-  await addJsonViewTab(TEST_JSON_URL);
-  await selectJsonViewContentTab("rawdata");
+  yield addJsonViewTab(TEST_JSON_URL);
+  yield selectJsonViewContentTab("rawdata");
 
-  let text = await getElementText(".textPanelBox .data");
+  let text = yield getElementText(".textPanelBox .data");
   is(text, result, "The charset parameter is ignored and UTF-8 is used.");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_invalid_json.js b/devtools/client/jsonview/test/browser_jsonview_invalid_json.js
index 3c51c8f24271..de3cbd74d443 100644
--- a/devtools/client/jsonview/test/browser_jsonview_invalid_json.js
+++ b/devtools/client/jsonview/test/browser_jsonview_invalid_json.js
@@ -7,14 +7,14 @@
 
 const TEST_JSON_URL = URL_ROOT + "invalid_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test invalid JSON started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let count = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   ok(count == 0, "There must be no row");
 
-  let text = await getElementText(".jsonPanelBox .jsonParseError");
+  let text = yield getElementText(".jsonPanelBox .jsonParseError");
   ok(text, "There must be an error description");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_manifest.js b/devtools/client/jsonview/test/browser_jsonview_manifest.js
index 7483244a0909..d8f79e3d266b 100644
--- a/devtools/client/jsonview/test/browser_jsonview_manifest.js
+++ b/devtools/client/jsonview/test/browser_jsonview_manifest.js
@@ -7,11 +7,11 @@
 
 const TEST_JSON_URL = URL_ROOT + "manifest_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test manifest JSON file started");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let count = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   is(count, 37, "There must be expected number of rows");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_nul.js b/devtools/client/jsonview/test/browser_jsonview_nul.js
index c2cde7c23882..5dac30780f94 100644
--- a/devtools/client/jsonview/test/browser_jsonview_nul.js
+++ b/devtools/client/jsonview/test/browser_jsonview_nul.js
@@ -5,14 +5,14 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   info("Test JSON with NUL started.");
 
   const TEST_JSON_URL = "data:application/json,\"foo_%00_bar\"";
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  await selectJsonViewContentTab("rawdata");
-  let rawData = await getElementText(".textPanelBox .data");
+  yield selectJsonViewContentTab("rawdata");
+  let rawData = yield getElementText(".textPanelBox .data");
   is(rawData, "\"foo_\u0000_bar\"",
      "The NUL character has been preserved.");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_object-type.js b/devtools/client/jsonview/test/browser_jsonview_object-type.js
index fcc5a713d459..790cf6a05f26 100644
--- a/devtools/client/jsonview/test/browser_jsonview_object-type.js
+++ b/devtools/client/jsonview/test/browser_jsonview_object-type.js
@@ -7,21 +7,21 @@
 
 const {ELLIPSIS} = require("devtools/shared/l10n");
 
-add_task(async function () {
+add_task(function* () {
   info("Test Object type property started");
 
   const TEST_JSON_URL = "data:application/json,{\"x\":{\"type\":\"string\"}}";
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let count = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   is(count, 2, "There must be two rows");
 
   // Collapse auto-expanded node.
-  await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+  yield clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
 
-  count = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  count = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   is(count, 1, "There must be one row");
 
-  let label = await getElementText(".jsonPanelBox .treeTable .objectCell");
+  let label = yield getElementText(".jsonPanelBox .treeTable .objectCell");
   is(label, `{${ELLIPSIS}}`, "The label must be indicating an object");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_save_json.js b/devtools/client/jsonview/test/browser_jsonview_save_json.js
index c3b79d7d4e94..da77c4e5ce30 100644
--- a/devtools/client/jsonview/test/browser_jsonview_save_json.js
+++ b/devtools/client/jsonview/test/browser_jsonview_save_json.js
@@ -84,15 +84,15 @@ registerCleanupFunction(function () {
   ok(!destDir.exists(), "Destination dir should be removed");
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Test 1 save JSON started");
 
   const JSON_FILE = "simple_json.json";
   const TEST_JSON_URL = URL_ROOT + JSON_FILE;
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
   let promise, rawJSON, prettyJSON;
-  await fetch(new Request(TEST_JSON_URL))
+  yield fetch(new Request(TEST_JSON_URL))
     .then(response => response.text())
     .then(function (data) {
       info("Fetched JSON contents.");
@@ -102,7 +102,7 @@ add_task(async function () {
 
   // Attempt to save original JSON via "Save As" command
   promise = awaitFileSave(JSON_FILE, "json");
-  await new Promise((resolve) => {
+  yield new Promise((resolve) => {
     info("Register to handle popupshown.");
     document.addEventListener("popupshown", function (event) {
       info("Context menu opened.");
@@ -116,53 +116,53 @@ add_task(async function () {
     rightClick("body");
     info("Right clicked.");
   });
-  await promise.then(getFileContents).then(function (data) {
+  yield promise.then(getFileContents).then(function (data) {
     is(data, rawJSON, "Original JSON contents should have been saved.");
   });
 
   // Attempt to save original JSON via "Save" button
   promise = awaitFileSave(JSON_FILE, "json");
-  await click(saveButton);
+  yield click(saveButton);
   info("Clicked Save button.");
-  await promise.then(getFileContents).then(function (data) {
+  yield promise.then(getFileContents).then(function (data) {
     is(data, rawJSON, "Original JSON contents should have been saved.");
   });
 
   // Attempt to save prettified JSON via "Save" button
-  await selectJsonViewContentTab("rawdata");
+  yield selectJsonViewContentTab("rawdata");
   info("Switched to Raw Data tab.");
-  await click(prettifyButton);
+  yield click(prettifyButton);
   info("Clicked Pretty Print button.");
   promise = awaitFileSave(JSON_FILE, "json");
-  await click(saveButton);
+  yield click(saveButton);
   info("Clicked Save button.");
-  await promise.then(getFileContents).then(function (data) {
+  yield promise.then(getFileContents).then(function (data) {
     is(data, prettyJSON, "Prettified JSON contents should have been saved.");
   });
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Test 2 save JSON started");
 
   const TEST_JSON_URL = "data:application/json,2";
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
   info("Checking that application/json adds .json extension by default.");
   let promise = awaitFileSave("index.json", "json");
-  await click(saveButton);
+  yield click(saveButton);
   info("Clicked Save button.");
-  await promise.then(getFileContents);
+  yield promise.then(getFileContents);
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Test 3 save JSON started");
 
   const TEST_JSON_URL = "data:application/manifest+json,3";
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
   info("Checking that application/manifest+json does not add .json extension.");
   let promise = awaitFileSave("index", null);
-  await click(saveButton);
+  yield click(saveButton);
   info("Clicked Save button.");
-  await promise.then(getFileContents);
+  yield promise.then(getFileContents);
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_slash.js b/devtools/client/jsonview/test/browser_jsonview_slash.js
index fc615a1f40ce..3adce84ac68c 100644
--- a/devtools/client/jsonview/test/browser_jsonview_slash.js
+++ b/devtools/client/jsonview/test/browser_jsonview_slash.js
@@ -5,12 +5,12 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   info("Test JSON with slash started.");
 
   const TEST_JSON_URL = "data:application/json,{\"a/b\":[1,2],\"a\":{\"b\":[3,4]}}";
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  let countBefore = await getElementCount(".jsonPanelBox .treeTable .treeRow");
+  let countBefore = yield getElementCount(".jsonPanelBox .treeTable .treeRow");
   is(countBefore, 7, "There must be seven rows");
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_theme.js b/devtools/client/jsonview/test/browser_jsonview_theme.js
index c01eb58a648b..8679f26e1864 100644
--- a/devtools/client/jsonview/test/browser_jsonview_theme.js
+++ b/devtools/client/jsonview/test/browser_jsonview_theme.js
@@ -7,24 +7,24 @@
 
 const TEST_JSON_URL = URL_ROOT + "valid_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test JSON theme started.");
 
   let oldPref = SpecialPowers.getCharPref("devtools.theme");
   SpecialPowers.setCharPref("devtools.theme", "light");
 
-  await addJsonViewTab(TEST_JSON_URL);
+  yield addJsonViewTab(TEST_JSON_URL);
 
-  is(await getTheme(), "theme-light", "The initial theme is light");
+  is(yield getTheme(), "theme-light", "The initial theme is light");
 
   SpecialPowers.setCharPref("devtools.theme", "dark");
-  is(await getTheme(), "theme-dark", "Theme changed to dark");
+  is(yield getTheme(), "theme-dark", "Theme changed to dark");
 
   SpecialPowers.setCharPref("devtools.theme", "firebug");
-  is(await getTheme(), "theme-firebug", "Theme changed to firebug");
+  is(yield getTheme(), "theme-firebug", "Theme changed to firebug");
 
   SpecialPowers.setCharPref("devtools.theme", "light");
-  is(await getTheme(), "theme-light", "Theme changed to light");
+  is(yield getTheme(), "theme-light", "Theme changed to light");
 
   SpecialPowers.setCharPref("devtools.theme", oldPref);
 });
diff --git a/devtools/client/jsonview/test/browser_jsonview_valid_json.js b/devtools/client/jsonview/test/browser_jsonview_valid_json.js
index 26354bc7cfa8..78a6fae4429e 100644
--- a/devtools/client/jsonview/test/browser_jsonview_valid_json.js
+++ b/devtools/client/jsonview/test/browser_jsonview_valid_json.js
@@ -7,35 +7,35 @@
 
 const TEST_JSON_URL = URL_ROOT + "valid_json.json";
 
-add_task(async function () {
+add_task(function* () {
   info("Test valid JSON started");
 
-  let tab = await addJsonViewTab(TEST_JSON_URL);
+  let tab = yield addJsonViewTab(TEST_JSON_URL);
 
   ok(tab.linkedBrowser.contentPrincipal.isNullPrincipal, "Should have null principal");
 
-  is(await countRows(), 3, "There must be three rows");
+  is(yield countRows(), 3, "There must be three rows");
 
-  let objectCellCount = await getElementCount(
+  let objectCellCount = yield getElementCount(
     ".jsonPanelBox .treeTable .objectCell");
   is(objectCellCount, 1, "There must be one object cell");
 
-  let objectCellText = await getElementText(
+  let objectCellText = yield getElementText(
     ".jsonPanelBox .treeTable .objectCell");
   is(objectCellText, "", "The summary is hidden when object is expanded");
 
   // Clicking the value does not collapse it (so that it can be selected and copied).
-  await clickJsonNode(".jsonPanelBox .treeTable .treeValueCell");
-  is(await countRows(), 3, "There must still be three rows");
+  yield clickJsonNode(".jsonPanelBox .treeTable .treeValueCell");
+  is(yield countRows(), 3, "There must still be three rows");
 
   // Clicking the label collapses the auto-expanded node.
-  await clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
-  is(await countRows(), 1, "There must be one row");
+  yield clickJsonNode(".jsonPanelBox .treeTable .treeLabel");
+  is(yield countRows(), 1, "There must be one row");
 
   // Collapsed nodes are preserved when switching panels.
-  await selectJsonViewContentTab("headers");
-  await selectJsonViewContentTab("json");
-  is(await countRows(), 1, "There must still be one row");
+  yield selectJsonViewContentTab("headers");
+  yield selectJsonViewContentTab("json");
+  is(yield countRows(), 1, "There must still be one row");
 });
 
 function countRows() {
diff --git a/devtools/client/memory/actions/allocations.js b/devtools/client/memory/actions/allocations.js
index 1a6aa15eb857..521319925c94 100644
--- a/devtools/client/memory/actions/allocations.js
+++ b/devtools/client/memory/actions/allocations.js
@@ -6,13 +6,13 @@
 const { actions, ALLOCATION_RECORDING_OPTIONS } = require("../constants");
 
 exports.toggleRecordingAllocationStacks = function (front) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch({ type: actions.TOGGLE_RECORD_ALLOCATION_STACKS_START });
 
     if (getState().recordingAllocationStacks) {
-      await front.stopRecordingAllocations();
+      yield front.stopRecordingAllocations();
     } else {
-      await front.startRecordingAllocations(ALLOCATION_RECORDING_OPTIONS);
+      yield front.startRecordingAllocations(ALLOCATION_RECORDING_OPTIONS);
     }
 
     dispatch({ type: actions.TOGGLE_RECORD_ALLOCATION_STACKS_END });
diff --git a/devtools/client/memory/actions/census-display.js b/devtools/client/memory/actions/census-display.js
index 3c68a19dca5d..416f5d1b5a1c 100644
--- a/devtools/client/memory/actions/census-display.js
+++ b/devtools/client/memory/actions/census-display.js
@@ -8,9 +8,9 @@ const { actions } = require("../constants");
 const { refresh } = require("./refresh");
 
 exports.setCensusDisplayAndRefresh = function (heapWorker, display) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch(setCensusDisplay(display));
-    await dispatch(refresh(heapWorker));
+    yield dispatch(refresh(heapWorker));
   };
 };
 
diff --git a/devtools/client/memory/actions/diffing.js b/devtools/client/memory/actions/diffing.js
index 3d396f9fadbe..9e180c29279a 100644
--- a/devtools/client/memory/actions/diffing.js
+++ b/devtools/client/memory/actions/diffing.js
@@ -46,7 +46,7 @@ const selectSnapshotForDiffing = exports.selectSnapshotForDiffing = function (sn
  * @param {snapshotModel} second
  */
 const takeCensusDiff = exports.takeCensusDiff = function (heapWorker, first, second) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     assert(snapshotIsDiffable(first),
            `First snapshot must be in a diffable state, found ${first.state}`);
     assert(snapshotIsDiffable(second),
@@ -88,7 +88,7 @@ const takeCensusDiff = exports.takeCensusDiff = function (heapWorker, first, sec
       opts.filter = filter || null;
 
       try {
-        ({ delta: report, parentMap } = await heapWorker.takeCensusDiff(
+        ({ delta: report, parentMap } = yield heapWorker.takeCensusDiff(
           first.path,
           second.path,
           { breakdown: display.breakdown },
@@ -122,7 +122,7 @@ const takeCensusDiff = exports.takeCensusDiff = function (heapWorker, first, sec
  * @param {HeapAnalysesClient} heapWorker
  */
 const refreshDiffing = exports.refreshDiffing = function (heapWorker) {
-  return function (dispatch, getState) {
+  return function* (dispatch, getState) {
     if (getState().diffing.secondSnapshotId === null) {
       return;
     }
@@ -152,11 +152,11 @@ const refreshDiffing = exports.refreshDiffing = function (heapWorker) {
  * @param {snapshotModel} snapshot
  */
 exports.selectSnapshotForDiffingAndRefresh = function (heapWorker, snapshot) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     assert(getState().diffing,
            "If we are selecting for diffing, we must be in diffing mode");
     dispatch(selectSnapshotForDiffing(snapshot));
-    await dispatch(refreshDiffing(heapWorker));
+    yield dispatch(refreshDiffing(heapWorker));
   };
 };
 
diff --git a/devtools/client/memory/actions/io.js b/devtools/client/memory/actions/io.js
index d70001a038e5..0bd0fb5809aa 100644
--- a/devtools/client/memory/actions/io.js
+++ b/devtools/client/memory/actions/io.js
@@ -15,8 +15,8 @@ const {
 const VALID_EXPORT_STATES = [states.SAVED, states.READ];
 
 exports.pickFileAndExportSnapshot = function (snapshot) {
-  return async function (dispatch, getState) {
-    let outputFile = await openFilePicker({
+  return function* (dispatch, getState) {
+    let outputFile = yield openFilePicker({
       title: L10N.getFormatStr("snapshot.io.save.window"),
       defaultName: OS.Path.basename(snapshot.path),
       filters: [[L10N.getFormatStr("snapshot.io.filter"), "*.fxsnapshot"]],
@@ -27,19 +27,19 @@ exports.pickFileAndExportSnapshot = function (snapshot) {
       return;
     }
 
-    await dispatch(exportSnapshot(snapshot, outputFile.path));
+    yield dispatch(exportSnapshot(snapshot, outputFile.path));
   };
 };
 
 const exportSnapshot = exports.exportSnapshot = function (snapshot, dest) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch({ type: actions.EXPORT_SNAPSHOT_START, snapshot });
 
     assert(VALID_EXPORT_STATES.includes(snapshot.state),
       `Snapshot is in invalid state for exporting: ${snapshot.state}`);
 
     try {
-      await OS.File.copy(snapshot.path, dest);
+      yield OS.File.copy(snapshot.path, dest);
     } catch (error) {
       reportException("exportSnapshot", error);
       dispatch({ type: actions.EXPORT_SNAPSHOT_ERROR, snapshot, error });
@@ -50,8 +50,8 @@ const exportSnapshot = exports.exportSnapshot = function (snapshot, dest) {
 };
 
 exports.pickFileAndImportSnapshotAndCensus = function (heapWorker) {
-  return async function (dispatch, getState) {
-    let input = await openFilePicker({
+  return function* (dispatch, getState) {
+    let input = yield openFilePicker({
       title: L10N.getFormatStr("snapshot.io.import.window"),
       filters: [[L10N.getFormatStr("snapshot.io.filter"), "*.fxsnapshot"]],
       mode: "open",
@@ -61,12 +61,12 @@ exports.pickFileAndImportSnapshotAndCensus = function (heapWorker) {
       return;
     }
 
-    await dispatch(importSnapshotAndCensus(heapWorker, input.path));
+    yield dispatch(importSnapshotAndCensus(heapWorker, input.path));
   };
 };
 
 const importSnapshotAndCensus = function (heapWorker, path) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     const snapshot = immutableUpdate(createSnapshot(getState()), {
       path,
       state: states.IMPORTING,
@@ -78,8 +78,8 @@ const importSnapshotAndCensus = function (heapWorker, path) {
     dispatch(selectSnapshot(snapshot.id));
 
     try {
-      await dispatch(readSnapshot(heapWorker, id));
-      await dispatch(computeSnapshotData(heapWorker, id));
+      yield dispatch(readSnapshot(heapWorker, id));
+      yield dispatch(computeSnapshotData(heapWorker, id));
     } catch (error) {
       reportException("importSnapshot", error);
       dispatch({ type: actions.IMPORT_SNAPSHOT_ERROR, error, id });
diff --git a/devtools/client/memory/actions/label-display.js b/devtools/client/memory/actions/label-display.js
index ee960edbed7a..82f7d4f5249d 100644
--- a/devtools/client/memory/actions/label-display.js
+++ b/devtools/client/memory/actions/label-display.js
@@ -12,10 +12,10 @@ const { refresh } = require("./refresh");
  * current data.
  */
 exports.setLabelDisplayAndRefresh = function (heapWorker, display) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     // Clears out all stored census data and sets the display.
     dispatch(setLabelDisplay(display));
-    await dispatch(refresh(heapWorker));
+    yield dispatch(refresh(heapWorker));
   };
 };
 
diff --git a/devtools/client/memory/actions/refresh.js b/devtools/client/memory/actions/refresh.js
index f9b687d695eb..801a4f867248 100644
--- a/devtools/client/memory/actions/refresh.js
+++ b/devtools/client/memory/actions/refresh.js
@@ -14,27 +14,27 @@ const snapshot = require("./snapshot");
  * @param {HeapAnalysesWorker} heapWorker
  */
 exports.refresh = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     switch (getState().view.state) {
       case viewState.DIFFING:
         assert(getState().diffing, "Should have diffing state if in diffing view");
-        await dispatch(refreshDiffing(heapWorker));
+        yield dispatch(refreshDiffing(heapWorker));
         return;
 
       case viewState.CENSUS:
-        await dispatch(snapshot.refreshSelectedCensus(heapWorker));
+        yield dispatch(snapshot.refreshSelectedCensus(heapWorker));
         return;
 
       case viewState.DOMINATOR_TREE:
-        await dispatch(snapshot.refreshSelectedDominatorTree(heapWorker));
+        yield dispatch(snapshot.refreshSelectedDominatorTree(heapWorker));
         return;
 
       case viewState.TREE_MAP:
-        await dispatch(snapshot.refreshSelectedTreeMap(heapWorker));
+        yield dispatch(snapshot.refreshSelectedTreeMap(heapWorker));
         return;
 
       case viewState.INDIVIDUALS:
-        await dispatch(snapshot.refreshIndividuals(heapWorker));
+        yield dispatch(snapshot.refreshIndividuals(heapWorker));
         return;
 
       default:
diff --git a/devtools/client/memory/actions/snapshot.js b/devtools/client/memory/actions/snapshot.js
index 85c804d5b810..fbc67a1f6049 100644
--- a/devtools/client/memory/actions/snapshot.js
+++ b/devtools/client/memory/actions/snapshot.js
@@ -34,18 +34,18 @@ const TaskCache = require("./task-cache");
  * @param {Object}
  */
 exports.takeSnapshotAndCensus = function (front, heapWorker) {
-  return async function (dispatch, getState) {
-    const id = await dispatch(takeSnapshot(front));
+  return function* (dispatch, getState) {
+    const id = yield dispatch(takeSnapshot(front));
     if (id === null) {
       return;
     }
 
-    await dispatch(readSnapshot(heapWorker, id));
+    yield dispatch(readSnapshot(heapWorker, id));
     if (getSnapshot(getState(), id).state !== states.READ) {
       return;
     }
 
-    await dispatch(computeSnapshotData(heapWorker, id));
+    yield dispatch(computeSnapshotData(heapWorker, id));
   };
 };
 
@@ -58,18 +58,18 @@ exports.takeSnapshotAndCensus = function (front, heapWorker) {
  * @param {snapshotId} id
  */
 const computeSnapshotData = exports.computeSnapshotData = function (heapWorker, id) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     if (getSnapshot(getState(), id).state !== states.READ) {
       return;
     }
 
     // Decide which type of census to take.
     const censusTaker = getCurrentCensusTaker(getState().view.state);
-    await dispatch(censusTaker(heapWorker, id));
+    yield dispatch(censusTaker(heapWorker, id));
 
     if (getState().view.state === viewState.DOMINATOR_TREE &&
         !getSnapshot(getState(), id).dominatorTree) {
-      await dispatch(computeAndFetchDominatorTree(heapWorker, id));
+      yield dispatch(computeAndFetchDominatorTree(heapWorker, id));
     }
   };
 };
@@ -82,13 +82,13 @@ const computeSnapshotData = exports.computeSnapshotData = function (heapWorker,
  * @param {snapshotId} id
  */
 exports.selectSnapshotAndRefresh = function (heapWorker, id) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     if (getState().diffing || getState().individuals) {
       dispatch(view.changeView(viewState.CENSUS));
     }
 
     dispatch(selectSnapshot(id));
-    await dispatch(refresh.refresh(heapWorker));
+    yield dispatch(refresh.refresh(heapWorker));
   };
 };
 
@@ -99,7 +99,7 @@ exports.selectSnapshotAndRefresh = function (heapWorker, id) {
  * @returns {Number|null}
  */
 const takeSnapshot = exports.takeSnapshot = function (front) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     if (getState().diffing || getState().individuals) {
       dispatch(view.changeView(viewState.CENSUS));
     }
@@ -111,7 +111,7 @@ const takeSnapshot = exports.takeSnapshot = function (front) {
 
     let path;
     try {
-      path = await front.saveHeapSnapshot();
+      path = yield front.saveHeapSnapshot();
     } catch (error) {
       reportException("takeSnapshot", error);
       dispatch({ type: actions.SNAPSHOT_ERROR, id, error });
@@ -136,7 +136,7 @@ TaskCache.declareCacheableTask({
     return id;
   },
 
-  task: async function (heapWorker, id, removeFromCache, dispatch, getState) {
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
     const snapshot = getSnapshot(getState(), id);
     assert([states.SAVED, states.IMPORTING].includes(snapshot.state),
            `Should only read a snapshot once. Found snapshot in state ${snapshot.state}`);
@@ -145,8 +145,8 @@ TaskCache.declareCacheableTask({
 
     dispatch({ type: actions.READ_SNAPSHOT_START, id });
     try {
-      await heapWorker.readHeapSnapshot(snapshot.path);
-      creationTime = await heapWorker.getCreationTime(snapshot.path);
+      yield heapWorker.readHeapSnapshot(snapshot.path);
+      creationTime = yield heapWorker.getCreationTime(snapshot.path);
     } catch (error) {
       removeFromCache();
       reportException("readSnapshot", error);
@@ -188,7 +188,7 @@ function makeTakeCensusTask({ getDisplay, getFilter, getCensus, beginAction,
       return `take-census-task-${thisTakeCensusTaskId}-${id}`;
     },
 
-    task: async function (heapWorker, id, removeFromCache, dispatch, getState) {
+    task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
       const snapshot = getSnapshot(getState(), id);
       if (!snapshot) {
         removeFromCache();
@@ -232,7 +232,7 @@ function makeTakeCensusTask({ getDisplay, getFilter, getCensus, beginAction,
         opts.filter = filter || null;
 
         try {
-          ({ report, parentMap } = await heapWorker.takeCensus(
+          ({ report, parentMap } = yield heapWorker.takeCensus(
             snapshot.path,
             { breakdown: display.breakdown },
             opts));
@@ -337,7 +337,7 @@ exports.focusIndividual = function (node) {
  */
 const fetchIndividuals = exports.fetchIndividuals =
 function (heapWorker, id, censusBreakdown, reportLeafIndex) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     if (getState().view.state !== viewState.INDIVIDUALS) {
       dispatch(view.changeView(viewState.INDIVIDUALS));
     }
@@ -347,7 +347,7 @@ function (heapWorker, id, censusBreakdown, reportLeafIndex) {
            "The snapshot should already be read into memory");
 
     if (!dominatorTreeIsComputed(snapshot)) {
-      await dispatch(computeAndFetchDominatorTree(heapWorker, id));
+      yield dispatch(computeAndFetchDominatorTree(heapWorker, id));
     }
 
     const snapshot_ = getSnapshot(getState(), id);
@@ -376,7 +376,7 @@ function (heapWorker, id, censusBreakdown, reportLeafIndex) {
       dispatch({ type: actions.FETCH_INDIVIDUALS_START });
 
       try {
-        ({ nodes } = await heapWorker.getCensusIndividuals({
+        ({ nodes } = yield heapWorker.getCensusIndividuals({
           dominatorTreeId,
           indices,
           censusBreakdown,
@@ -410,7 +410,7 @@ function (heapWorker, id, censusBreakdown, reportLeafIndex) {
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.refreshIndividuals = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     assert(getState().view.state === viewState.INDIVIDUALS,
            "Should be in INDIVIDUALS view.");
 
@@ -437,7 +437,7 @@ exports.refreshIndividuals = function (heapWorker) {
         return;
     }
 
-    await dispatch(fetchIndividuals(heapWorker,
+    yield dispatch(fetchIndividuals(heapWorker,
                                     individuals.id,
                                     individuals.censusBreakdown,
                                     individuals.indices));
@@ -451,7 +451,7 @@ exports.refreshIndividuals = function (heapWorker) {
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.refreshSelectedCensus = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     let snapshot = getState().snapshots.find(s => s.selected);
     if (!snapshot || snapshot.state !== states.READ) {
       return;
@@ -465,7 +465,7 @@ exports.refreshSelectedCensus = function (heapWorker) {
     // task action will follow through and ensure that a census is taken.
     if ((snapshot.census && snapshot.census.state === censusState.SAVED) ||
         !snapshot.census) {
-      await dispatch(takeCensus(heapWorker, snapshot.id));
+      yield dispatch(takeCensus(heapWorker, snapshot.id));
     }
   };
 };
@@ -477,7 +477,7 @@ exports.refreshSelectedCensus = function (heapWorker) {
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.refreshSelectedTreeMap = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     let snapshot = getState().snapshots.find(s => s.selected);
     if (!snapshot || snapshot.state !== states.READ) {
       return;
@@ -491,7 +491,7 @@ exports.refreshSelectedTreeMap = function (heapWorker) {
     // task action will follow through and ensure that a census is taken.
     if ((snapshot.treeMap && snapshot.treeMap.state === treeMapState.SAVED) ||
         !snapshot.treeMap) {
-      await dispatch(takeTreeMap(heapWorker, snapshot.id));
+      yield dispatch(takeTreeMap(heapWorker, snapshot.id));
     }
   };
 };
@@ -511,7 +511,7 @@ TaskCache.declareCacheableTask({
     return id;
   },
 
-  task: async function (heapWorker, id, removeFromCache, dispatch, getState) {
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
     const snapshot = getSnapshot(getState(), id);
     assert(!(snapshot.dominatorTree && snapshot.dominatorTree.dominatorTreeId),
            "Should not re-compute dominator trees");
@@ -520,7 +520,7 @@ TaskCache.declareCacheableTask({
 
     let dominatorTreeId;
     try {
-      dominatorTreeId = await heapWorker.computeDominatorTree(snapshot.path);
+      dominatorTreeId = yield heapWorker.computeDominatorTree(snapshot.path);
     } catch (error) {
       removeFromCache();
       reportException("actions/snapshot/computeDominatorTree", error);
@@ -549,7 +549,7 @@ TaskCache.declareCacheableTask({
     return id;
   },
 
-  task: async function (heapWorker, id, removeFromCache, dispatch, getState) {
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
     const snapshot = getSnapshot(getState(), id);
     assert(dominatorTreeIsComputed(snapshot),
            "Should have dominator tree model and it should be computed");
@@ -564,7 +564,7 @@ TaskCache.declareCacheableTask({
       dispatch({ type: actions.FETCH_DOMINATOR_TREE_START, id, display });
 
       try {
-        root = await heapWorker.getDominatorTree({
+        root = yield heapWorker.getDominatorTree({
           dominatorTreeId: snapshot.dominatorTree.dominatorTreeId,
           breakdown: display.breakdown,
           maxRetainingPaths: Preferences.get("devtools.memory.max-retaining-paths"),
@@ -597,8 +597,7 @@ exports.fetchImmediatelyDominated = TaskCache.declareCacheableTask({
     return `${id}-${lazyChildren.key()}`;
   },
 
-  task: async function (heapWorker, id, lazyChildren, removeFromCache, dispatch,
-                        getState) {
+  task: function* (heapWorker, id, lazyChildren, removeFromCache, dispatch, getState) {
     const snapshot = getSnapshot(getState(), id);
     assert(snapshot.dominatorTree, "Should have dominator tree model");
     assert(snapshot.dominatorTree.state === dominatorTreeState.LOADED ||
@@ -615,7 +614,7 @@ exports.fetchImmediatelyDominated = TaskCache.declareCacheableTask({
       dispatch({ type: actions.FETCH_IMMEDIATELY_DOMINATED_START, id });
 
       try {
-        response = await heapWorker.getImmediatelyDominated({
+        response = yield heapWorker.getImmediatelyDominated({
           dominatorTreeId: snapshot.dominatorTree.dominatorTreeId,
           breakdown: display.breakdown,
           nodeId: lazyChildren.parentNodeId(),
@@ -657,14 +656,14 @@ TaskCache.declareCacheableTask({
     return id;
   },
 
-  task: async function (heapWorker, id, removeFromCache, dispatch, getState) {
-    const dominatorTreeId = await dispatch(computeDominatorTree(heapWorker, id));
+  task: function* (heapWorker, id, removeFromCache, dispatch, getState) {
+    const dominatorTreeId = yield dispatch(computeDominatorTree(heapWorker, id));
     if (dominatorTreeId === null) {
       removeFromCache();
       return null;
     }
 
-    const root = await dispatch(fetchDominatorTree(heapWorker, id));
+    const root = yield dispatch(fetchDominatorTree(heapWorker, id));
     removeFromCache();
 
     if (!root) {
@@ -681,7 +680,7 @@ TaskCache.declareCacheableTask({
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.refreshSelectedDominatorTree = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     let snapshot = getState().snapshots.find(s => s.selected);
     if (!snapshot) {
       return;
@@ -699,9 +698,9 @@ exports.refreshSelectedDominatorTree = function (heapWorker) {
     // then takeSnapshotAndCensus will finish the job for us
     if (snapshot.state === states.READ) {
       if (snapshot.dominatorTree) {
-        await dispatch(fetchDominatorTree(heapWorker, snapshot.id));
+        yield dispatch(fetchDominatorTree(heapWorker, snapshot.id));
       } else {
-        await dispatch(computeAndFetchDominatorTree(heapWorker, snapshot.id));
+        yield dispatch(computeAndFetchDominatorTree(heapWorker, snapshot.id));
       }
     }
   };
@@ -726,7 +725,7 @@ const selectSnapshot = exports.selectSnapshot = function (id) {
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.clearSnapshots = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     let snapshots = getState().snapshots.filter(s => {
       let snapshotReady = s.state === states.READ || s.state === states.ERROR;
       let censusReady = (s.treeMap && s.treeMap.state === treeMapState.SAVED) ||
@@ -746,7 +745,7 @@ exports.clearSnapshots = function (heapWorker) {
       dispatch(view.popView());
     }
 
-    await Promise.all(snapshots.map(snapshot => {
+    yield Promise.all(snapshots.map(snapshot => {
       return heapWorker.deleteHeapSnapshot(snapshot.path).catch(error => {
         reportException("clearSnapshots", error);
         dispatch({ type: actions.SNAPSHOT_ERROR, id: snapshot.id, error });
@@ -764,11 +763,11 @@ exports.clearSnapshots = function (heapWorker) {
  * @param {snapshotModel} snapshot
  */
 exports.deleteSnapshot = function (heapWorker, snapshot) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch({ type: actions.DELETE_SNAPSHOTS_START, ids: [snapshot.id] });
 
     try {
-      await heapWorker.deleteHeapSnapshot(snapshot.path);
+      yield heapWorker.deleteHeapSnapshot(snapshot.path);
     } catch (error) {
       reportException("deleteSnapshot", error);
       dispatch({ type: actions.SNAPSHOT_ERROR, id: snapshot.id, error });
diff --git a/devtools/client/memory/actions/task-cache.js b/devtools/client/memory/actions/task-cache.js
index ed67330e7f85..14e44d0c382d 100644
--- a/devtools/client/memory/actions/task-cache.js
+++ b/devtools/client/memory/actions/task-cache.js
@@ -65,7 +65,7 @@ TaskCache.declareCacheableTask = function ({ getCacheKey, task }) {
   const cache = new TaskCache();
 
   return function (...args) {
-    return async function (dispatch, getState) {
+    return function* (dispatch, getState) {
       const key = getCacheKey(...args);
 
       const extantResult = cache.get(key);
@@ -80,10 +80,10 @@ TaskCache.declareCacheableTask = function ({ getCacheKey, task }) {
         resolve = r;
       }));
 
-      resolve(dispatch(async function () {
+      resolve(dispatch(function* () {
         try {
           args.push(() => cache.remove(key), dispatch, getState);
-          return await task(...args);
+          return yield* task(...args);
         } catch (error) {
           // Don't perma-cache errors.
           if (cache.get(key)) {
@@ -93,7 +93,7 @@ TaskCache.declareCacheableTask = function ({ getCacheKey, task }) {
         }
       }));
 
-      return cache.get(key);
+      return yield cache.get(key);
     };
   };
 };
diff --git a/devtools/client/memory/actions/tree-map-display.js b/devtools/client/memory/actions/tree-map-display.js
index 268b47d520c6..69b205603e15 100644
--- a/devtools/client/memory/actions/tree-map-display.js
+++ b/devtools/client/memory/actions/tree-map-display.js
@@ -11,9 +11,9 @@ const { refresh } = require("./refresh");
  * census.
  */
 exports.setTreeMapAndRefresh = function (heapWorker, display) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch(setTreeMap(display));
-    await dispatch(refresh(heapWorker));
+    yield dispatch(refresh(heapWorker));
   };
 };
 
diff --git a/devtools/client/memory/actions/view.js b/devtools/client/memory/actions/view.js
index 07bba59bd0e5..5ff508840eda 100644
--- a/devtools/client/memory/actions/view.js
+++ b/devtools/client/memory/actions/view.js
@@ -47,9 +47,9 @@ const popView = exports.popView = function () {
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.changeViewAndRefresh = function (view, heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch(changeView(view));
-    await dispatch(refresh.refresh(heapWorker));
+    yield dispatch(refresh.refresh(heapWorker));
   };
 };
 
@@ -60,8 +60,8 @@ exports.changeViewAndRefresh = function (view, heapWorker) {
  * @param {HeapAnalysesClient} heapWorker
  */
 exports.popViewAndRefresh = function (heapWorker) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     dispatch(popView());
-    await dispatch(refresh.refresh(heapWorker));
+    yield dispatch(refresh.refresh(heapWorker));
   };
 };
diff --git a/devtools/client/memory/initializer.js b/devtools/client/memory/initializer.js
index 6ea8565ce5da..024fffe6f035 100644
--- a/devtools/client/memory/initializer.js
+++ b/devtools/client/memory/initializer.js
@@ -12,6 +12,7 @@ const { require } = BrowserLoaderModule.BrowserLoader({
   baseURI: "resource://devtools/client/memory/",
   window
 });
+const { Task } = require("devtools/shared/task");
 const { createFactory, createElement } = require("devtools/client/shared/vendor/react");
 const ReactDOM = require("devtools/client/shared/vendor/react-dom");
 const { Provider } = require("devtools/client/shared/vendor/react-redux");
@@ -31,7 +32,7 @@ var gToolbox, gFront, gHeapAnalysesClient;
  */
 var gStore, gRoot, gApp, gProvider, unsubscribe, isHighlighted;
 
-var initialize = async function () {
+var initialize = Task.async(function* () {
   gRoot = document.querySelector("#app");
   gStore = Store();
   gApp = createElement(App,
@@ -39,16 +40,16 @@ var initialize = async function () {
   gProvider = createElement(Provider, { store: gStore }, gApp);
   ReactDOM.render(gProvider, gRoot);
   unsubscribe = gStore.subscribe(onStateChange);
-};
+});
 
-var destroy = async function () {
+var destroy = Task.async(function* () {
   const ok = ReactDOM.unmountComponentAtNode(gRoot);
   assert(ok, "Should successfully unmount the memory tool's top level React component");
 
   unsubscribe();
 
   gStore = gRoot = gApp = gProvider = unsubscribe = isHighlighted = null;
-};
+});
 
 /**
  * Fired on any state change, currently only handles toggling
diff --git a/devtools/client/memory/panel.js b/devtools/client/memory/panel.js
index 987bd263adca..a7a20d96d95b 100644
--- a/devtools/client/memory/panel.js
+++ b/devtools/client/memory/panel.js
@@ -4,6 +4,7 @@
 
 "use strict";
 
+const { Task } = require("devtools/shared/task");
 const EventEmitter = require("devtools/shared/old-event-emitter");
 const { MemoryFront } = require("devtools/shared/fronts/memory");
 const HeapAnalysesClient = require("devtools/shared/heapsnapshot/HeapAnalysesClient");
@@ -16,7 +17,7 @@ function MemoryPanel(iframeWindow, toolbox) {
 }
 
 MemoryPanel.prototype = {
-  async open() {
+  open: Task.async(function* () {
     if (this._opening) {
       return this._opening;
     }
@@ -24,13 +25,13 @@ MemoryPanel.prototype = {
     this.panelWin.gToolbox = this._toolbox;
     this.panelWin.gTarget = this.target;
 
-    const rootForm = await this.target.root;
+    const rootForm = yield this.target.root;
     this.panelWin.gFront = new MemoryFront(this.target.client,
                                            this.target.form,
                                            rootForm);
     this.panelWin.gHeapAnalysesClient = new HeapAnalysesClient();
 
-    await this.panelWin.gFront.attach();
+    yield this.panelWin.gFront.attach();
 
     this._opening = this.panelWin.initialize().then(() => {
       this.isReady = true;
@@ -39,7 +40,7 @@ MemoryPanel.prototype = {
     });
 
     return this._opening;
-  },
+  }),
 
   // DevToolPanel API
 
@@ -47,13 +48,13 @@ MemoryPanel.prototype = {
     return this._toolbox.target;
   },
 
-  async destroy() {
+  destroy: Task.async(function* () {
     // Make sure this panel is not already destroyed.
     if (this._destroyer) {
       return this._destroyer;
     }
 
-    await this.panelWin.gFront.detach();
+    yield this.panelWin.gFront.detach();
 
     this._destroyer = this.panelWin.destroy().then(() => {
       // Destroy front to ensure packet handler is removed from client
@@ -66,7 +67,7 @@ MemoryPanel.prototype = {
     });
 
     return this._destroyer;
-  }
+  })
 };
 
 exports.MemoryPanel = MemoryPanel;
diff --git a/devtools/client/memory/test/browser/browser_memory_allocationStackDisplay_01.js b/devtools/client/memory/test/browser/browser_memory_allocationStackDisplay_01.js
index fdd0c6ad1a17..60cd5c456d52 100644
--- a/devtools/client/memory/test/browser/browser_memory_allocationStackDisplay_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_allocationStackDisplay_01.js
@@ -13,7 +13,7 @@ const { changeView } = require("devtools/client/memory/actions/view");
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const heapWorker = panel.panelWin.gHeapAnalysesClient;
   const front = panel.panelWin.gFront;
   const { getState, dispatch } = panel.panelWin.gStore;
@@ -24,13 +24,13 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   dispatch(censusDisplayActions.setCensusDisplay(censusDisplays.invertedAllocationStack));
   is(getState().censusDisplay.breakdown.by, "allocationStack");
 
-  await dispatch(toggleRecordingAllocationStacks(front));
+  yield dispatch(toggleRecordingAllocationStacks(front));
   ok(getState().allocations.recording);
 
   // Let some allocations build up.
-  await waitForTime(500);
+  yield waitForTime(500);
 
-  await dispatch(takeSnapshotAndCensus(front, heapWorker));
+  yield dispatch(takeSnapshotAndCensus(front, heapWorker));
 
   const names = [...doc.querySelectorAll(".frame-link-function-display-name")];
   ok(names.length, "Should have rendered some allocation stack tree items");
diff --git a/devtools/client/memory/test/browser/browser_memory_clear_snapshots.js b/devtools/client/memory/test/browser/browser_memory_clear_snapshots.js
index b40fd69ba2d6..7a5686566e98 100644
--- a/devtools/client/memory/test/browser/browser_memory_clear_snapshots.js
+++ b/devtools/client/memory/test/browser/browser_memory_clear_snapshots.js
@@ -10,7 +10,7 @@
 const { treeMapState } = require("devtools/client/memory/constants");
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const { gStore, document } = panel.panelWin;
   const { getState } = gStore;
 
@@ -21,7 +21,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   info("Take two snapshots");
   takeSnapshot(panel.panelWin);
   takeSnapshot(panel.panelWin);
-  await waitUntilState(gStore, state =>
+  yield waitUntilState(gStore, state =>
   state.snapshots.length === 2 &&
   state.snapshots[0].treeMap && state.snapshots[1].treeMap &&
   state.snapshots[0].treeMap.state === treeMapState.SAVED &&
@@ -31,7 +31,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   is(snapshotEls.length, 2, "Two snapshots visible");
 
   info("Click on Clear Snapshots");
-  await clearSnapshots(panel.panelWin);
+  yield clearSnapshots(panel.panelWin);
   is(getState().snapshots.length, 0, "No snapshots in store");
   snapshotEls = document.querySelectorAll("#memory-tool-container .list li");
   is(snapshotEls.length, 0, "No snapshot visible");
diff --git a/devtools/client/memory/test/browser/browser_memory_diff_01.js b/devtools/client/memory/test/browser/browser_memory_diff_01.js
index 79767959fb06..70ea9e4ab888 100644
--- a/devtools/client/memory/test/browser/browser_memory_diff_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_diff_01.js
@@ -12,7 +12,7 @@ const {
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const store = panel.panelWin.gStore;
   const { getState } = store;
   const doc = panel.panelWin.document;
@@ -22,20 +22,20 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   // Take two snapshots.
   const takeSnapshotButton = doc.getElementById("take-snapshot");
   EventUtils.synthesizeMouseAtCenter(takeSnapshotButton, {}, panel.panelWin);
-  await waitForTime(1000);
+  yield waitForTime(1000);
   EventUtils.synthesizeMouseAtCenter(takeSnapshotButton, {}, panel.panelWin);
 
   // Enable diffing mode.
   const diffButton = doc.getElementById("diff-snapshots");
   EventUtils.synthesizeMouseAtCenter(diffButton, {}, panel.panelWin);
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state =>
                          !!state.diffing &&
                          state.diffing.state === diffingState.SELECTING);
   ok(true, "Clicking the diffing button put us into the diffing state.");
   is(getDisplayedSnapshotStatus(doc), "Select the baseline snapshot");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots.length === 2 &&
     state.snapshots[0].treeMap && state.snapshots[1].treeMap &&
     state.snapshots[0].treeMap.state === treeMapState.SAVED &&
@@ -46,7 +46,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   // Select the first snapshot.
   EventUtils.synthesizeMouseAtCenter(listItems[0], {}, panel.panelWin);
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state =>
                          state.diffing.state === diffingState.SELECTING &&
                          state.diffing.firstSnapshotId);
@@ -55,7 +55,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   // Select the second snapshot.
   EventUtils.synthesizeMouseAtCenter(listItems[1], {}, panel.panelWin);
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state =>
                          state.diffing.state === diffingState.TAKING_DIFF);
   ok(true, "Selecting two snapshots for diffing triggers computing the diff");
@@ -63,7 +63,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   // .startsWith because the ellipsis is lost in translation.
   ok(getDisplayedSnapshotStatus(doc).startsWith("Computing difference"));
 
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state => state.diffing.state === diffingState.TOOK_DIFF);
   ok(true, "And that diff is computed successfully");
   is(getDisplayedSnapshotStatus(doc), null, "No status text anymore");
diff --git a/devtools/client/memory/test/browser/browser_memory_displays_01.js b/devtools/client/memory/test/browser/browser_memory_displays_01.js
index 03fbb7e1d995..28bc2a589ddd 100644
--- a/devtools/client/memory/test/browser/browser_memory_displays_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_displays_01.js
@@ -10,7 +10,7 @@ const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser
 const { viewState, censusState } = require("devtools/client/memory/constants");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const { gStore, document } = panel.panelWin;
 
   const { dispatch } = panel.panelWin.gStore;
@@ -20,9 +20,9 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   }
   dispatch(changeView(viewState.CENSUS));
 
-  await takeSnapshot(panel.panelWin);
+  yield takeSnapshot(panel.panelWin);
 
-  await waitUntilState(gStore, state =>
+  yield waitUntilState(gStore, state =>
     state.snapshots[0].census &&
     state.snapshots[0].census.state === censusState.SAVED);
 
@@ -30,7 +30,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   ["Function", "js::Shape", "Object", "strings"].forEach(findNameCell);
 
-  await setCensusDisplay(panel.panelWin, censusDisplays.allocationStack);
+  yield setCensusDisplay(panel.panelWin, censusDisplays.allocationStack);
   info("Check allocation stack heap view");
   [L10N.getStr("tree-item.nostack")].forEach(findNameCell);
 
diff --git a/devtools/client/memory/test/browser/browser_memory_dominator_trees_01.js b/devtools/client/memory/test/browser/browser_memory_dominator_trees_01.js
index 4d4052f349ba..90bc633f3a96 100644
--- a/devtools/client/memory/test/browser/browser_memory_dominator_trees_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_dominator_trees_01.js
@@ -17,7 +17,7 @@ const { changeView } = require("devtools/client/memory/actions/view");
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_big_tree.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   // Taking snapshots and computing dominator trees is slow :-/
   requestLongerTimeout(4);
 
@@ -34,7 +34,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   // Wait for the dominator tree to be computed and fetched.
 
-  await waitUntilDominatorTreeState(store, [dominatorTreeState.LOADED]);
+  yield waitUntilDominatorTreeState(store, [dominatorTreeState.LOADED]);
   ok(true, "Computed and fetched the dominator tree.");
 
   // Expand all the dominator tree nodes that are eagerly fetched, except for
@@ -83,7 +83,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   EventUtils.synthesizeMouseAtCenter(doc.querySelector(`.node-${deepest.nodeId}`),
                                      {},
                                      panel.panelWin);
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.focused.nodeId === deepest.nodeId);
   ok(doc.querySelector(`.node-${deepest.nodeId}`).classList.contains("focused"),
      "The deepest node should be focused now");
@@ -92,7 +92,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   // loaded subtree.
 
   EventUtils.synthesizeKey("VK_RIGHT", {}, panel.panelWin);
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.expanded.has(deepest.nodeId));
   is(getState().snapshots[0].dominatorTree.state,
      dominatorTreeState.INCREMENTAL_FETCHING,
@@ -102,7 +102,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   // Wait for the incremental fetch to complete.
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "And the incremental fetch completes.");
   ok(doc.querySelector(`.node-${deepest.nodeId}`).classList.contains("focused"),
@@ -142,7 +142,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   // Select the newly loaded first child by pressing the right arrow once more.
 
   EventUtils.synthesizeKey("VK_RIGHT", {}, panel.panelWin);
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.focused === firstChild);
   ok(doc.querySelector(`.node-${firstChild.nodeId}`).classList.contains("focused"),
      "The first child should now be focused");
diff --git a/devtools/client/memory/test/browser/browser_memory_dominator_trees_02.js b/devtools/client/memory/test/browser/browser_memory_dominator_trees_02.js
index fdf89632d6f4..72bc52567f00 100644
--- a/devtools/client/memory/test/browser/browser_memory_dominator_trees_02.js
+++ b/devtools/client/memory/test/browser/browser_memory_dominator_trees_02.js
@@ -18,7 +18,7 @@ function clickOnNodeArrow(node, panel) {
                                      {}, panel.panelWin);
 }
 
-this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ panel }) {
   // Taking snapshots and computing dominator trees is slow :-/
   requestLongerTimeout(4);
 
@@ -33,7 +33,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
   EventUtils.synthesizeMouseAtCenter(takeSnapshotButton, {}, panel.panelWin);
 
   // Wait for the dominator tree to be computed and fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
@@ -47,7 +47,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
   const rootNode = doc.querySelector(`.node-${root.nodeId}`);
   clickOnNodeArrow(rootNode, panel);
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     !state.snapshots[0].dominatorTree.expanded.has(root.nodeId));
@@ -56,7 +56,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
   // Click on root arrow to expand it again
   clickOnNodeArrow(rootNode, panel);
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.expanded.has(root.nodeId));
diff --git a/devtools/client/memory/test/browser/browser_memory_filter_01.js b/devtools/client/memory/test/browser/browser_memory_filter_01.js
index f9d5aba54233..7950d987b943 100644
--- a/devtools/client/memory/test/browser/browser_memory_filter_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_filter_01.js
@@ -14,7 +14,7 @@ const { changeViewAndRefresh, changeView } = require("devtools/client/memory/act
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const heapWorker = panel.panelWin.gHeapAnalysesClient;
   const store = panel.panelWin.gStore;
   const { dispatch } = store;
@@ -25,7 +25,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   const takeSnapshotButton = doc.getElementById("take-snapshot");
   EventUtils.synthesizeMouseAtCenter(takeSnapshotButton, {}, panel.panelWin);
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots.length === 1 &&
     state.snapshots[0].census &&
     state.snapshots[0].census.state === censusState.SAVING);
@@ -34,13 +34,13 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   EventUtils.synthesizeMouseAtCenter(filterInput, {}, panel.panelWin);
   EventUtils.sendString("js::Shape", panel.panelWin);
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots.length === 1 &&
     state.snapshots[0].census &&
     state.snapshots[0].census.state === censusState.SAVING);
   ok(true, "adding a filter string should trigger census recompute");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots.length === 1 &&
     state.snapshots[0].census &&
     state.snapshots[0].census.state === censusState.SAVED);
@@ -58,13 +58,13 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   ok(true, "change view to dominator tree");
 
   // Wait for the dominator tree to be computed and fetched.
-  await waitUntilDominatorTreeState(store, [dominatorTreeState.LOADED]);
+  yield waitUntilDominatorTreeState(store, [dominatorTreeState.LOADED]);
   ok(true, "computed and fetched the dominator tree.");
 
   dispatch(changeViewAndRefresh(viewState.CENSUS, heapWorker));
   ok(true, "change view back to census");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots.length === 1 &&
     state.snapshots[0].census &&
     state.snapshots[0].census.state === censusState.SAVED);
diff --git a/devtools/client/memory/test/browser/browser_memory_individuals_01.js b/devtools/client/memory/test/browser/browser_memory_individuals_01.js
index a86eb3efa1b6..b902a569ba6c 100644
--- a/devtools/client/memory/test/browser/browser_memory_individuals_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_individuals_01.js
@@ -15,7 +15,7 @@ const { changeView } = require("devtools/client/memory/actions/view");
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const store = panel.panelWin.gStore;
   const { dispatch } = store;
   const doc = panel.panelWin.document;
@@ -27,7 +27,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   const takeSnapshotButton = doc.getElementById("take-snapshot");
   EventUtils.synthesizeMouseAtCenter(takeSnapshotButton, {}, panel.panelWin);
 
-  await waitUntilState(store, state => {
+  yield waitUntilState(store, state => {
     return state.snapshots.length === 1 &&
            state.snapshots[0].census &&
            state.snapshots[0].census.state === censusState.SAVED;
@@ -39,7 +39,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   const individualsButton = doc.querySelector(".individuals-button");
   EventUtils.synthesizeMouseAtCenter(individualsButton, {}, panel.panelWin);
 
-  await waitUntilState(store, state => {
+  yield waitUntilState(store, state => {
     return state.view.state === viewState.INDIVIDUALS &&
            state.individuals &&
            state.individuals.state === individualsState.FETCHED;
@@ -56,7 +56,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   ok(popViewButton, "Should be showing the #pop-view-button");
   EventUtils.synthesizeMouseAtCenter(popViewButton, {}, panel.panelWin);
 
-  await waitUntilState(store, state => {
+  yield waitUntilState(store, state => {
     return state.view.state === viewState.CENSUS;
   });
 
diff --git a/devtools/client/memory/test/browser/browser_memory_keyboard-snapshot-list.js b/devtools/client/memory/test/browser/browser_memory_keyboard-snapshot-list.js
index 0af3e0e766bd..3271c3330b0a 100644
--- a/devtools/client/memory/test/browser/browser_memory_keyboard-snapshot-list.js
+++ b/devtools/client/memory/test/browser/browser_memory_keyboard-snapshot-list.js
@@ -16,7 +16,7 @@ const { changeView } = require("devtools/client/memory/actions/view");
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ panel }) {
   // Creating snapshots already takes ~25 seconds on linux 32 debug machines
   // which makes the test very likely to go over the allowed timeout
   requestLongerTimeout(2);
@@ -34,22 +34,22 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots.length == 3 &&
     state.snapshots.every(s => s.census && s.census.state === censusState.SAVED));
   ok(true, "All snapshots censuses are in SAVED state");
 
-  await waitUntilSnapshotSelected(store, 2);
+  yield waitUntilSnapshotSelected(store, 2);
   ok(true, "Third snapshot selected after creating all snapshots.");
 
   info("Press ACCEL+UP key, expect second snapshot selected.");
   EventUtils.synthesizeKey("VK_UP", { accelKey: true }, panel.panelWin);
-  await waitUntilSnapshotSelected(store, 1);
+  yield waitUntilSnapshotSelected(store, 1);
   ok(true, "Second snapshot selected after alt+UP.");
 
   info("Press ACCEL+UP key, expect first snapshot selected.");
   EventUtils.synthesizeKey("VK_UP", { accelKey: true }, panel.panelWin);
-  await waitUntilSnapshotSelected(store, 0);
+  yield waitUntilSnapshotSelected(store, 0);
   ok(true, "First snapshot is selected after ACCEL+UP");
 
   info("Check ACCEL+UP is a noop when the first snapshot is selected.");
@@ -59,20 +59,20 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
 
   info("Press ACCEL+DOWN key, expect second snapshot selected.");
   EventUtils.synthesizeKey("VK_DOWN", { accelKey: true }, panel.panelWin);
-  await waitUntilSnapshotSelected(store, 1);
+  yield waitUntilSnapshotSelected(store, 1);
   ok(true, "Second snapshot is selected after ACCEL+DOWN");
 
   info("Click on first node.");
   let firstNode = doc.querySelector(".tree .heap-tree-item-name");
   EventUtils.synthesizeMouseAtCenter(firstNode, {}, panel.panelWin);
-  await waitUntilState(store, state => state.snapshots[1].census.focused ===
+  yield waitUntilState(store, state => state.snapshots[1].census.focused ===
       state.snapshots[1].census.report.children[0]
   );
   ok(true, "First root is selected after click.");
 
   info("Press DOWN key, expect second root focused.");
   EventUtils.synthesizeKey("VK_DOWN", {}, panel.panelWin);
-  await waitUntilState(store, state => state.snapshots[1].census.focused ===
+  yield waitUntilState(store, state => state.snapshots[1].census.focused ===
       state.snapshots[1].census.report.children[1]
   );
   ok(true, "Second root is selected after pressing DOWN.");
@@ -80,7 +80,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
 
   info("Press UP key, expect second root focused.");
   EventUtils.synthesizeKey("VK_UP", {}, panel.panelWin);
-  await waitUntilState(store, state => state.snapshots[1].census.focused ===
+  yield waitUntilState(store, state => state.snapshots[1].census.focused ===
       state.snapshots[1].census.report.children[0]
   );
   ok(true, "First root is selected after pressing UP.");
@@ -88,7 +88,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ panel }) {
 
   info("Press ACCEL+DOWN key, expect third snapshot selected.");
   EventUtils.synthesizeKey("VK_DOWN", { accelKey: true }, panel.panelWin);
-  await waitUntilSnapshotSelected(store, 2);
+  yield waitUntilSnapshotSelected(store, 2);
   ok(true, "Thirdˆ snapshot is selected after ACCEL+DOWN");
 
   info("Check ACCEL+DOWN is a noop when the last snapshot is selected.");
diff --git a/devtools/client/memory/test/browser/browser_memory_keyboard.js b/devtools/client/memory/test/browser/browser_memory_keyboard.js
index 23ebdb3c4201..f04e054b6731 100644
--- a/devtools/client/memory/test/browser/browser_memory_keyboard.js
+++ b/devtools/client/memory/test/browser/browser_memory_keyboard.js
@@ -34,7 +34,7 @@ function waitUntilExpanded(store, node) {
     state.snapshots[0].census.expanded.has(node.id));
 }
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const heapWorker = panel.panelWin.gHeapAnalysesClient;
   const front = panel.panelWin.gFront;
   const store = panel.panelWin.gStore;
@@ -45,7 +45,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   is(getState().censusDisplay.breakdown.by, "coarseType");
 
-  await dispatch(takeSnapshotAndCensus(front, heapWorker));
+  yield dispatch(takeSnapshotAndCensus(front, heapWorker));
   let census = getState().snapshots[0].census;
   let root1 = census.report.children[0];
   let root2 = census.report.children[0];
@@ -56,51 +56,51 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   info("Click on first node.");
   let firstNode = doc.querySelector(".tree .heap-tree-item-name");
   EventUtils.synthesizeMouseAtCenter(firstNode, {}, panel.panelWin);
-  await waitUntilFocused(store, root1);
+  yield waitUntilFocused(store, root1);
   ok(true, "First root is selected after click.");
 
   info("Press DOWN key, expect second root focused.");
   EventUtils.synthesizeKey("VK_DOWN", {}, panel.panelWin);
-  await waitUntilFocused(store, root2);
+  yield waitUntilFocused(store, root2);
   ok(true, "Second root is selected after pressing DOWN arrow.");
 
   info("Press DOWN key, expect third root focused.");
   EventUtils.synthesizeKey("VK_DOWN", {}, panel.panelWin);
-  await waitUntilFocused(store, root3);
+  yield waitUntilFocused(store, root3);
   ok(true, "Third root is selected after pressing DOWN arrow.");
 
   info("Press DOWN key, expect fourth root focused.");
   EventUtils.synthesizeKey("VK_DOWN", {}, panel.panelWin);
-  await waitUntilFocused(store, root4);
+  yield waitUntilFocused(store, root4);
   ok(true, "Fourth root is selected after pressing DOWN arrow.");
 
   info("Press UP key, expect third root focused.");
   EventUtils.synthesizeKey("VK_UP", {}, panel.panelWin);
-  await waitUntilFocused(store, root3);
+  yield waitUntilFocused(store, root3);
   ok(true, "Third root is selected after pressing UP arrow.");
 
   info("Press UP key, expect second root focused.");
   EventUtils.synthesizeKey("VK_UP", {}, panel.panelWin);
-  await waitUntilFocused(store, root2);
+  yield waitUntilFocused(store, root2);
   ok(true, "Second root is selected after pressing UP arrow.");
 
   info("Press UP key, expect first root focused.");
   EventUtils.synthesizeKey("VK_UP", {}, panel.panelWin);
-  await waitUntilFocused(store, root1);
+  yield waitUntilFocused(store, root1);
   ok(true, "First root is selected after pressing UP arrow.");
 
   info("Press RIGHT key");
   EventUtils.synthesizeKey("VK_RIGHT", {}, panel.panelWin);
-  await waitUntilExpanded(store, root1);
+  yield waitUntilExpanded(store, root1);
   ok(true, "Root node is expanded.");
 
   info("Press RIGHT key, expect first child focused.");
   EventUtils.synthesizeKey("VK_RIGHT", {}, panel.panelWin);
-  await waitUntilFocused(store, child1);
+  yield waitUntilFocused(store, child1);
   ok(true, "First child is selected after pressing RIGHT arrow.");
 
   info("Press LEFT key, expect first root focused.");
   EventUtils.synthesizeKey("VK_LEFT", {}, panel.panelWin);
-  await waitUntilFocused(store, root1);
+  yield waitUntilFocused(store, root1);
   ok(true, "First root is selected after pressing LEFT arrow.");
 });
diff --git a/devtools/client/memory/test/browser/browser_memory_no_allocation_stacks.js b/devtools/client/memory/test/browser/browser_memory_no_allocation_stacks.js
index e624da3dacfa..0f309d6245d5 100644
--- a/devtools/client/memory/test/browser/browser_memory_no_allocation_stacks.js
+++ b/devtools/client/memory/test/browser/browser_memory_no_allocation_stacks.js
@@ -12,7 +12,7 @@ const { changeView } = require("devtools/client/memory/actions/view");
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const heapWorker = panel.panelWin.gHeapAnalysesClient;
   const front = panel.panelWin.gFront;
   const { getState, dispatch } = panel.panelWin.gStore;
@@ -23,8 +23,8 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   ok(!getState().allocations.recording,
      "Should not be recording allocagtions");
 
-  await dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await dispatch(censusDisplayActions.setCensusDisplayAndRefresh(
+  yield dispatch(takeSnapshotAndCensus(front, heapWorker));
+  yield dispatch(censusDisplayActions.setCensusDisplayAndRefresh(
     heapWorker,
     censusDisplays.allocationStack));
 
diff --git a/devtools/client/memory/test/browser/browser_memory_no_auto_expand.js b/devtools/client/memory/test/browser/browser_memory_no_auto_expand.js
index d683181c726a..d0c80153b2a5 100644
--- a/devtools/client/memory/test/browser/browser_memory_no_auto_expand.js
+++ b/devtools/client/memory/test/browser/browser_memory_no_auto_expand.js
@@ -12,7 +12,7 @@ const { changeView } = require("devtools/client/memory/actions/view");
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_steady_allocation.html";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const heapWorker = panel.panelWin.gHeapAnalysesClient;
   const front = panel.panelWin.gFront;
   const { getState, dispatch } = panel.panelWin.gStore;
@@ -20,7 +20,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   dispatch(changeView(viewState.CENSUS));
 
-  await dispatch(takeSnapshotAndCensus(front, heapWorker));
+  yield dispatch(takeSnapshotAndCensus(front, heapWorker));
 
   is(getState().allocations.recording, false);
   const recordingCheckbox = doc.getElementById("record-allocation-stacks-checkbox");
diff --git a/devtools/client/memory/test/browser/browser_memory_percents_01.js b/devtools/client/memory/test/browser/browser_memory_percents_01.js
index f1c129ef3239..c3ed37530957 100644
--- a/devtools/client/memory/test/browser/browser_memory_percents_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_percents_01.js
@@ -21,7 +21,7 @@ function checkCells(cells) {
   }
 }
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const heapWorker = panel.panelWin.gHeapAnalysesClient;
   const front = panel.panelWin.gFront;
   const { getState, dispatch } = panel.panelWin.gStore;
@@ -29,7 +29,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
 
   dispatch(changeView(viewState.CENSUS));
 
-  await dispatch(takeSnapshotAndCensus(front, heapWorker));
+  yield dispatch(takeSnapshotAndCensus(front, heapWorker));
   is(getState().censusDisplay.breakdown.by, "coarseType",
      "Should be using coarse type breakdown");
 
diff --git a/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js b/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js
index 47177ad0162d..b25891d70e3a 100644
--- a/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js
+++ b/devtools/client/memory/test/browser/browser_memory_refresh_does_not_leak.js
@@ -15,9 +15,9 @@ const { getLabelAndShallowSize } = require("devtools/shared/heapsnapshot/Dominat
 
 const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser/doc_empty.html";
 
-async function getWindowsInSnapshot(front) {
+function* getWindowsInSnapshot(front) {
   dumpn("Taking snapshot.");
-  const path = await front.saveHeapSnapshot();
+  const path = yield front.saveHeapSnapshot();
   dumpn("Took snapshot with path = " + path);
   const snapshot = ChromeUtils.readHeapSnapshot(path);
   dumpn("Read snapshot into memory, taking census.");
@@ -50,17 +50,17 @@ const DESCRIPTION = {
   }
 };
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const front = panel.panelWin.gFront;
 
-  const startWindows = await getWindowsInSnapshot(front);
+  const startWindows = yield getWindowsInSnapshot(front);
   dumpn("Initial windows found = " + startWindows.map(w => "0x" +
                                      w.toString(16)).join(", "));
   is(startWindows.length, 1);
 
-  await refreshTab();
+  yield refreshTab();
 
-  const endWindows = await getWindowsInSnapshot(front);
+  const endWindows = yield getWindowsInSnapshot(front);
   is(endWindows.length, 1);
 
   if (endWindows.length === 1) {
@@ -71,7 +71,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   dumpn("(This may fail if a moving GC has relocated the initial Window objects.)");
 
   dumpn("Taking full runtime snapshot.");
-  const path = await front.saveHeapSnapshot({ boundaries: { runtime: true } });
+  const path = yield front.saveHeapSnapshot({ boundaries: { runtime: true } });
   dumpn("Full runtime's snapshot path = " + path);
 
   dumpn("Reading full runtime heap snapshot.");
diff --git a/devtools/client/memory/test/browser/browser_memory_simple_01.js b/devtools/client/memory/test/browser/browser_memory_simple_01.js
index d28da9c776a5..c4b78150a32e 100644
--- a/devtools/client/memory/test/browser/browser_memory_simple_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_simple_01.js
@@ -11,7 +11,7 @@ const TEST_URL = "http://example.com/browser/devtools/client/memory/test/browser
 const { viewState, censusState } = require("devtools/client/memory/constants");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const { gStore, document } = panel.panelWin;
   const { getState, dispatch } = gStore;
 
@@ -21,14 +21,14 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   is(getState().snapshots.length, 0, "Starts with no snapshots in store");
   is(snapshotEls.length, 0, "No snapshots rendered");
 
-  await takeSnapshot(panel.panelWin);
+  yield takeSnapshot(panel.panelWin);
   snapshotEls = document.querySelectorAll("#memory-tool-container .list li");
   is(getState().snapshots.length, 1, "One snapshot was created in store");
   is(snapshotEls.length, 1, "One snapshot was rendered");
   ok(snapshotEls[0].classList.contains("selected"),
      "Only snapshot has `selected` class");
 
-  await takeSnapshot(panel.panelWin);
+  yield takeSnapshot(panel.panelWin);
   snapshotEls = document.querySelectorAll("#memory-tool-container .list li");
   is(getState().snapshots.length, 2, "Two snapshots created in store");
   is(snapshotEls.length, 2, "Two snapshots rendered");
@@ -37,7 +37,7 @@ this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
   ok(snapshotEls[1].classList.contains("selected"),
      "Second snapshot has `selected` class");
 
-  await waitUntilCensusState(gStore, s => s.census,
+  yield waitUntilCensusState(gStore, s => s.census,
                              [censusState.SAVED, censusState.SAVED]);
 
   ok(document.querySelector(".heap-tree-item-name"),
diff --git a/devtools/client/memory/test/browser/browser_memory_transferHeapSnapshot_e10s_01.js b/devtools/client/memory/test/browser/browser_memory_transferHeapSnapshot_e10s_01.js
index 00e3e284a2bc..5d5a2cabec44 100644
--- a/devtools/client/memory/test/browser/browser_memory_transferHeapSnapshot_e10s_01.js
+++ b/devtools/client/memory/test/browser/browser_memory_transferHeapSnapshot_e10s_01.js
@@ -11,17 +11,17 @@
 
 const TEST_URL = "data:text/html,<html><body></body></html>";
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const memoryFront = panel.panelWin.gFront;
   ok(memoryFront, "Should get the MemoryFront");
 
-  const snapshotFilePath = await memoryFront.saveHeapSnapshot({
+  const snapshotFilePath = yield memoryFront.saveHeapSnapshot({
     // Force a copy so that we go through the HeapSnapshotFileActor's
     // transferHeapSnapshot request and exercise this code path on e10s.
     forceCopy: true
   });
 
-  ok(!!(await OS.File.stat(snapshotFilePath)),
+  ok(!!(yield OS.File.stat(snapshotFilePath)),
      "Should have the heap snapshot file");
 
   const snapshot = ChromeUtils.readHeapSnapshot(snapshotFilePath);
diff --git a/devtools/client/memory/test/browser/browser_memory_tree_map-01.js b/devtools/client/memory/test/browser/browser_memory_tree_map-01.js
index 46d6d68af6a6..ca564a658a68 100644
--- a/devtools/client/memory/test/browser/browser_memory_tree_map-01.js
+++ b/devtools/client/memory/test/browser/browser_memory_tree_map-01.js
@@ -11,7 +11,7 @@ const D3_SCRIPT = '<script type="application/javascript" ' +
                   'src="chrome://devtools/content/shared/vendor/d3.js>';
 const TEST_URL = `data:text/html,<html><body>${D3_SCRIPT}</body></html>`;
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const document = panel.panelWin.document;
   const window = panel.panelWin;
   const div = document.createElement("div");
diff --git a/devtools/client/memory/test/browser/browser_memory_tree_map-02.js b/devtools/client/memory/test/browser/browser_memory_tree_map-02.js
index a2e41f93a8da..db549c8ca3f8 100644
--- a/devtools/client/memory/test/browser/browser_memory_tree_map-02.js
+++ b/devtools/client/memory/test/browser/browser_memory_tree_map-02.js
@@ -14,7 +14,7 @@ const PIXEL_SCROLL_MODE = 0;
 const PIXEL_DELTA = 10;
 const MAX_RAF_LOOP = 1000;
 
-this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
   const panelWin = panel.panelWin;
   const panelDoc = panelWin.document;
   const div = panelDoc.createElement("div");
diff --git a/devtools/client/memory/test/browser/head.js b/devtools/client/memory/test/browser/head.js
index 38416eb24617..47702d416c57 100644
--- a/devtools/client/memory/test/browser/head.js
+++ b/devtools/client/memory/test/browser/head.js
@@ -21,25 +21,25 @@ Services.prefs.setBoolPref("devtools.memory.enabled", true);
 /**
  * Open the memory panel for the given tab.
  */
-this.openMemoryPanel = async function (tab) {
+this.openMemoryPanel = Task.async(function* (tab) {
   info("Opening memory panel.");
   const target = TargetFactory.forTab(tab);
-  const toolbox = await gDevTools.showToolbox(target, "memory");
+  const toolbox = yield gDevTools.showToolbox(target, "memory");
   info("Memory panel shown successfully.");
   let panel = toolbox.getCurrentPanel();
   return { tab, panel };
-};
+});
 
 /**
  * Close the memory panel for the given tab.
  */
-this.closeMemoryPanel = async function (tab) {
+this.closeMemoryPanel = Task.async(function* (tab) {
   info("Closing memory panel.");
   const target = TargetFactory.forTab(tab);
   const toolbox = gDevTools.getToolbox(target);
-  await toolbox.destroy();
+  yield toolbox.destroy();
   info("Closed memory panel successfully.");
-};
+});
 
 /**
  * Return a test function that adds a tab with the given url, opens the memory
@@ -48,32 +48,32 @@ this.closeMemoryPanel = async function (tab) {
  *
  * Example usage:
  *
- *     this.test = makeMemoryTest(TEST_URL, async function ({ tab, panel }) {
+ *     this.test = makeMemoryTest(TEST_URL, function* ({ tab, panel }) {
  *         // Your tests go here...
  *     });
  */
 function makeMemoryTest(url, generator) {
-  return async function () {
+  return Task.async(function* () {
     waitForExplicitFinish();
 
     // It can take a long time to save a snapshot to disk, read the snapshots
     // back from disk, and finally perform analyses on them.
     requestLongerTimeout(2);
 
-    const tab = await addTab(url);
-    const results = await openMemoryPanel(tab);
+    const tab = yield addTab(url);
+    const results = yield openMemoryPanel(tab);
 
     try {
-      await generator(results);
+      yield* generator(results);
     } catch (err) {
       ok(false, "Got an error: " + DevToolsUtils.safeErrorString(err));
     }
 
-    await closeMemoryPanel(tab);
-    await removeTab(tab);
+    yield closeMemoryPanel(tab);
+    yield removeTab(tab);
 
     finish();
-  };
+  });
 }
 
 function dumpn(msg) {
diff --git a/devtools/client/memory/test/chrome/head.js b/devtools/client/memory/test/chrome/head.js
index 20f34f8b7e34..0dbc47892e71 100644
--- a/devtools/client/memory/test/chrome/head.js
+++ b/devtools/client/memory/test/chrome/head.js
@@ -10,6 +10,7 @@ var { require } = BrowserLoader({
 });
 var { Assert } = require("resource://testing-common/Assert.jsm");
 var Services = require("Services");
+var { Task } = require("devtools/shared/task");
 
 var EXPECTED_DTU_ASSERT_FAILURE_COUNT = 0;
 
diff --git a/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html b/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html
index 418dbc36b204..5dddb96ec5c8 100644
--- a/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html
+++ b/devtools/client/memory/test/chrome/test_CensusTreeItem_01.html
@@ -16,11 +16,11 @@ Test that children pointers show up at the correct times.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
-             await renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
+             yield renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
                inverted: true,
                depth: 0,
              })), container);
@@ -28,7 +28,7 @@ Test that children pointers show up at the correct times.
              ok(!container.querySelector(".children-pointer"),
                 "Don't show children pointer for roots when we are inverted");
 
-             await renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
+             yield renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
                inverted: true,
                depth: 1,
              })), container);
@@ -36,7 +36,7 @@ Test that children pointers show up at the correct times.
              ok(container.querySelector(".children-pointer"),
                 "Do show children pointer for non-roots when we are inverted");
 
-             await renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
+             yield renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
                inverted: false,
                item: immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS.item, { children: undefined }),
              })), container);
@@ -44,7 +44,7 @@ Test that children pointers show up at the correct times.
              ok(!container.querySelector(".children-pointer"),
                 "Don't show children pointer when non-inverted and no children");
 
-             await renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
+             yield renderComponent(CensusTreeItem(immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS, {
                inverted: false,
                depth: 0,
                item: immutableUpdate(TEST_CENSUS_TREE_ITEM_PROPS.item, { children: [{}] }),
@@ -58,7 +58,7 @@ Test that children pointers show up at the correct times.
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html b/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html
index 6937e1fc3115..631c988a6ab3 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTreeItem_01.html
@@ -16,11 +16,11 @@ Test that we don't display `JS::ubi::RootList` for the root, and instead show "G
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
-             await renderComponent(DominatorTreeItem({
+             yield renderComponent(DominatorTreeItem({
                item: makeTestDominatorTreeNode({ label: ["other", "JS::ubi::RootList"] }),
                depth: 0,
                arrow: dom.div(),
@@ -38,7 +38,7 @@ Test that we don't display `JS::ubi::RootList` for the root, and instead show "G
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_DominatorTree_01.html b/devtools/client/memory/test/chrome/test_DominatorTree_01.html
index 518d3504c841..e6bf08c0c9bc 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTree_01.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTree_01.html
@@ -16,7 +16,7 @@ Test that we show a place holder for a subtree we are lazily fetching.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
@@ -26,7 +26,7 @@ Test that we show a place holder for a subtree we are lazily fetching.
              const expanded = new Set();
              expanded.add(root.nodeId);
 
-             await renderComponent(DominatorTreeComponent(immutableUpdate(TEST_DOMINATOR_TREE_PROPS, {
+             yield renderComponent(DominatorTreeComponent(immutableUpdate(TEST_DOMINATOR_TREE_PROPS, {
                dominatorTree: immutableUpdate(TEST_DOMINATOR_TREE_PROPS.dominatorTree, {
                  expanded,
                  root,
@@ -43,7 +43,7 @@ Test that we show a place holder for a subtree we are lazily fetching.
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_DominatorTree_02.html b/devtools/client/memory/test/chrome/test_DominatorTree_02.html
index ae8e80b1dcc3..e2159dcfb65d 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTree_02.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTree_02.html
@@ -16,7 +16,7 @@ Test that we show a link to load more children when some (but not all) are loade
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
@@ -29,7 +29,7 @@ Test that we show a link to load more children when some (but not all) are loade
              const expanded = new Set();
              expanded.add(root.nodeId);
 
-             await renderComponent(DominatorTreeComponent(immutableUpdate(TEST_DOMINATOR_TREE_PROPS, {
+             yield renderComponent(DominatorTreeComponent(immutableUpdate(TEST_DOMINATOR_TREE_PROPS, {
                dominatorTree: immutableUpdate(TEST_DOMINATOR_TREE_PROPS.dominatorTree, {
                  expanded,
                  root,
@@ -43,7 +43,7 @@ Test that we show a link to load more children when some (but not all) are loade
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_DominatorTree_03.html b/devtools/client/memory/test/chrome/test_DominatorTree_03.html
index 2f75ed711daa..c51c2f67108c 100644
--- a/devtools/client/memory/test/chrome/test_DominatorTree_03.html
+++ b/devtools/client/memory/test/chrome/test_DominatorTree_03.html
@@ -16,7 +16,7 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-        window.onload = async function () {
+        window.onload = Task.async(function* () {
           try {
             const container = document.getElementById("container");
 
@@ -32,7 +32,7 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
             const expanded = new Set();
             expanded.add(root.nodeId);
 
-            let component = await renderComponent(
+            let component = yield renderComponent(
               DominatorTreeComponent(immutableUpdate(
                 TEST_DOMINATOR_TREE_PROPS,
                 {
@@ -48,7 +48,7 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
             is(container.querySelectorAll(".arrow.open").length, 1,
                 "Should display one expanded arrow");
 
-            await renderComponent(
+            yield renderComponent(
               DominatorTreeComponent(immutableUpdate(
                 TEST_DOMINATOR_TREE_PROPS,
                 {
@@ -70,7 +70,7 @@ Test that expanded DominatorTreeItems are correctly rendered and updated
           } finally {
             SimpleTest.finish();
           }
-        };
+        });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Heap_01.html b/devtools/client/memory/test/chrome/test_Heap_01.html
index ebd9076ea805..e8efbd1935c9 100644
--- a/devtools/client/memory/test/chrome/test_Heap_01.html
+++ b/devtools/client/memory/test/chrome/test_Heap_01.html
@@ -15,7 +15,7 @@ Test that rendering a dominator tree error is handled correctly.
         <script src="head.js" type="application/javascript"></script>
 
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              ok(React, "Should get React");
              ok(Heap, "Should get Heap");
@@ -33,7 +33,7 @@ Test that rendering a dominator tree error is handled correctly.
                })
              });
 
-             await renderComponent(Heap(props), container);
+             yield renderComponent(Heap(props), container);
 
              ok(container.querySelector(".error"), "Should render an error view");
              ok(container.textContent.includes(errorMessage),
@@ -43,7 +43,7 @@ Test that rendering a dominator tree error is handled correctly.
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Heap_02.html b/devtools/client/memory/test/chrome/test_Heap_02.html
index 630f7972d4e9..0dd1ba9ea8d9 100644
--- a/devtools/client/memory/test/chrome/test_Heap_02.html
+++ b/devtools/client/memory/test/chrome/test_Heap_02.html
@@ -14,7 +14,7 @@ Test that the currently selected view is rendered.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              ok(React, "Should get React");
              ok(Heap, "Should get Heap");
@@ -24,7 +24,7 @@ Test that the currently selected view is rendered.
 
              // Dominator tree view.
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                view: { state: viewState.DOMINATOR_TREE, },
              })), container);
 
@@ -33,7 +33,7 @@ Test that the currently selected view is rendered.
 
              // Census view.
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                view: { state: viewState.CENSUS, },
              })), container);
 
@@ -42,7 +42,7 @@ Test that the currently selected view is rendered.
 
              // Diffing view.
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                view: { state: viewState.DIFFING, },
                snapshot: null,
                diffing: {
@@ -59,7 +59,7 @@ Test that the currently selected view is rendered.
 
              // Initial view.
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: null,
                diffing: null,
              })), container);
@@ -71,7 +71,7 @@ Test that the currently selected view is rendered.
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Heap_03.html b/devtools/client/memory/test/chrome/test_Heap_03.html
index d33a30e7e531..687707c39eab 100644
--- a/devtools/client/memory/test/chrome/test_Heap_03.html
+++ b/devtools/client/memory/test/chrome/test_Heap_03.html
@@ -15,12 +15,12 @@ but not in other dominator tree states.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
              for (let state of [dominatorTreeState.COMPUTING, dominatorTreeState.FETCHING]) {
-               await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+               yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                  view: { state: viewState.DOMINATOR_TREE, },
                  snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                    dominatorTree: immutableUpdate(TEST_HEAP_PROPS.snapshot.dominatorTree, {
@@ -36,7 +36,7 @@ but not in other dominator tree states.
              }
 
              for (let state of [dominatorTreeState.LOADED, dominatorTreeState.INCREMENTAL_FETCHING]) {
-               await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+               yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                  view: { state: viewState.DOMINATOR_TREE, },
                  snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                    dominatorTree: immutableUpdate(TEST_HEAP_PROPS.snapshot.dominatorTree, {
@@ -50,7 +50,7 @@ but not in other dominator tree states.
                   `Should not show a throbber for state = ${state}`);
              }
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                view: { state: viewState.DOMINATOR_TREE, },
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  dominatorTree: {
@@ -67,7 +67,7 @@ but not in other dominator tree states.
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Heap_04.html b/devtools/client/memory/test/chrome/test_Heap_04.html
index c80c0a6104a6..751a57228e8e 100644
--- a/devtools/client/memory/test/chrome/test_Heap_04.html
+++ b/devtools/client/memory/test/chrome/test_Heap_04.html
@@ -14,11 +14,11 @@ Test that we show the "hey you're not recording allocation stacks" message at th
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, {
                    report: {
@@ -49,7 +49,7 @@ Test that we show the "hey you're not recording allocation stacks" message at th
              ok(container.querySelector(".no-allocation-stacks"),
                 "When there are no allocation stacks, we should show the message");
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, {
                    report: {
@@ -90,7 +90,7 @@ Test that we show the "hey you're not recording allocation stacks" message at th
              ok(!container.querySelector(".no-allocation-stacks"),
                 "When there are allocation stacks, we should not show the message");
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, {
                    report: {
@@ -114,7 +114,7 @@ Test that we show the "hey you're not recording allocation stacks" message at th
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Heap_05.html b/devtools/client/memory/test/chrome/test_Heap_05.html
index 4662e09e89f7..57406f619c71 100644
--- a/devtools/client/memory/test/chrome/test_Heap_05.html
+++ b/devtools/client/memory/test/chrome/test_Heap_05.html
@@ -14,11 +14,11 @@ Test that we show a message when the census results are empty.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, {
                    report: {
@@ -79,7 +79,7 @@ Test that we show a message when the census results are empty.
                state: censusState.SAVED,
              };
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, emptyCensus),
                }),
@@ -91,7 +91,7 @@ Test that we show a message when the census results are empty.
 
              // Empty Diffing Report
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                view: { state: viewState.DIFFING, },
                diffing: {
                  firstSnapshotId: 1,
@@ -108,7 +108,7 @@ Test that we show a message when the census results are empty.
 
              // Empty Filtered Census
 
-             await renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
+             yield renderComponent(Heap(immutableUpdate(TEST_HEAP_PROPS, {
                snapshot: immutableUpdate(TEST_HEAP_PROPS.snapshot, {
                  census: immutableUpdate(TEST_HEAP_PROPS.snapshot.census, immutableUpdate(emptyCensus, {
                    filter: "zzzz"
@@ -125,7 +125,7 @@ Test that we show a message when the census results are empty.
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_List_01.html b/devtools/client/memory/test/chrome/test_List_01.html
index a3fd2f70a99f..e50790ec79b4 100644
--- a/devtools/client/memory/test/chrome/test_List_01.html
+++ b/devtools/client/memory/test/chrome/test_List_01.html
@@ -15,7 +15,7 @@ Test to verify the delete button calls the onDelete handler for an item
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
           try {
             const container = document.getElementById("container");
 
@@ -26,7 +26,7 @@ Test to verify the delete button calls the onDelete handler for an item
                 index: snapshot.index + index
               }));
 
-            await renderComponent(
+            yield renderComponent(
               List({
                 itemComponent: SnapshotListItem,
                 onClick: noop,
@@ -67,7 +67,7 @@ Test to verify the delete button calls the onDelete handler for an item
           } finally {
             SimpleTest.finish();
           }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_ShortestPaths_01.html b/devtools/client/memory/test/chrome/test_ShortestPaths_01.html
index b0bace20c4b0..fdecde765a7f 100644
--- a/devtools/client/memory/test/chrome/test_ShortestPaths_01.html
+++ b/devtools/client/memory/test/chrome/test_ShortestPaths_01.html
@@ -23,11 +23,11 @@ Test that the ShortestPaths component properly renders a graph of the merged sho
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
-             await renderComponent(ShortestPaths(TEST_SHORTEST_PATHS_PROPS), container);
+             yield renderComponent(ShortestPaths(TEST_SHORTEST_PATHS_PROPS), container);
 
              let found1 = false;
              let found2 = false;
@@ -105,7 +105,7 @@ Test that the ShortestPaths component properly renders a graph of the merged sho
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_ShortestPaths_02.html b/devtools/client/memory/test/chrome/test_ShortestPaths_02.html
index 5b48bd49f6a6..501cffc9f79c 100644
--- a/devtools/client/memory/test/chrome/test_ShortestPaths_02.html
+++ b/devtools/client/memory/test/chrome/test_ShortestPaths_02.html
@@ -23,11 +23,11 @@ Test that the ShortestPaths component renders a suggestion to select a node when
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
-             await renderComponent(ShortestPaths(immutableUpdate(TEST_SHORTEST_PATHS_PROPS,
+             yield renderComponent(ShortestPaths(immutableUpdate(TEST_SHORTEST_PATHS_PROPS,
                                                                  { graph: null })),
                                    container);
 
@@ -38,7 +38,7 @@ Test that the ShortestPaths component renders a suggestion to select a node when
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html b/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html
index f4796c97e482..c5a07e0be96c 100644
--- a/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html
+++ b/devtools/client/memory/test/chrome/test_SnapshotListItem_01.html
@@ -16,11 +16,11 @@ path.
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
           try {
             const container = document.getElementById("container");
 
-            await renderComponent(
+            yield renderComponent(
               SnapshotListItem(TEST_SNAPSHOT_LIST_ITEM_PROPS),
               container
             );
@@ -33,7 +33,7 @@ path.
                 {item: immutableUpdate(TEST_SNAPSHOT, {path: null})}
             );
 
-            await renderComponent(
+            yield renderComponent(
               SnapshotListItem(pathlessProps),
               container
             );
@@ -46,7 +46,7 @@ path.
           } finally {
             SimpleTest.finish();
           }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_Toolbar_01.html b/devtools/client/memory/test/chrome/test_Toolbar_01.html
index c2c234e09e90..bb16fefe2ff9 100644
--- a/devtools/client/memory/test/chrome/test_Toolbar_01.html
+++ b/devtools/client/memory/test/chrome/test_Toolbar_01.html
@@ -14,14 +14,14 @@ Test that the Toolbar component shows the view switcher only at the appropriate
     <pre id="test">
         <script src="head.js" type="application/javascript"></script>
         <script type="application/javascript">
-         window.onload = async function () {
+         window.onload = Task.async(function* () {
            try {
              const container = document.getElementById("container");
 
              // Census and dominator tree views.
 
              for (let view of [viewState.CENSUS, viewState.DOMINATOR_TREE]) {
-               await renderComponent(Toolbar(immutableUpdate(TEST_TOOLBAR_PROPS, {
+               yield renderComponent(Toolbar(immutableUpdate(TEST_TOOLBAR_PROPS, {
                  view: { state: view },
                })), container);
 
@@ -29,7 +29,7 @@ Test that the Toolbar component shows the view switcher only at the appropriate
                   `The view selector is shown in view = ${view}`);
              }
 
-             await renderComponent(Toolbar(immutableUpdate(TEST_TOOLBAR_PROPS, {
+             yield renderComponent(Toolbar(immutableUpdate(TEST_TOOLBAR_PROPS, {
                view: { state: viewState.DIFFING, },
              })), container);
 
@@ -40,7 +40,7 @@ Test that the Toolbar component shows the view switcher only at the appropriate
            } finally {
              SimpleTest.finish();
            }
-         };
+         });
         </script>
     </pre>
 </body>
diff --git a/devtools/client/memory/test/chrome/test_TreeMap_01.html b/devtools/client/memory/test/chrome/test_TreeMap_01.html
index 15be48b5e164..d35134bf9772 100644
--- a/devtools/client/memory/test/chrome/test_TreeMap_01.html
+++ b/devtools/client/memory/test/chrome/test_TreeMap_01.html
@@ -20,11 +20,11 @@ Test that the Tree Map correctly renders onto 2 managed canvases.
   <pre id="test">
     <script src="head.js" type="application/javascript"></script>
     <script type="application/javascript">
-      window.onload = async function () {
+      window.onload = Task.async(function*() {
         try {
           const container = document.getElementById("container");
 
-          await renderComponent(TreeMap(TEST_TREE_MAP_PROPS), container);
+          yield renderComponent(TreeMap(TEST_TREE_MAP_PROPS), container);
 
           let treeMapContainer = container.querySelector(".tree-map-container");
           ok(treeMapContainer, "Component creates a container");
@@ -37,7 +37,7 @@ Test that the Tree Map correctly renders onto 2 managed canvases.
         } finally {
           SimpleTest.finish();
         }
-      };
+      });
     </script>
   </pre>
 </body>
diff --git a/devtools/client/memory/test/unit/head.js b/devtools/client/memory/test/unit/head.js
index a58329e4f24c..81ce6423cb96 100644
--- a/devtools/client/memory/test/unit/head.js
+++ b/devtools/client/memory/test/unit/head.js
@@ -17,6 +17,7 @@ var { FileUtils } = require("resource://gre/modules/FileUtils.jsm");
 var { TargetFactory } = require("devtools/client/framework/target");
 var promise = require("promise");
 var defer = require("devtools/shared/defer");
+var { Task } = require("devtools/shared/task");
 var { expectState } = require("devtools/server/actors/common");
 var HeapSnapshotFileUtils = require("devtools/shared/heapsnapshot/HeapSnapshotFileUtils");
 var HeapAnalysesClient = require("devtools/shared/heapsnapshot/HeapAnalysesClient");
@@ -49,28 +50,28 @@ function StubbedMemoryFront() {
   this.dbg = initDebugger();
 }
 
-StubbedMemoryFront.prototype.attach = async function () {
+StubbedMemoryFront.prototype.attach = Task.async(function* () {
   this.state = "attached";
-};
+});
 
-StubbedMemoryFront.prototype.detach = async function () {
+StubbedMemoryFront.prototype.detach = Task.async(function* () {
   this.state = "detached";
-};
+});
 
 StubbedMemoryFront.prototype.saveHeapSnapshot = expectState("attached",
-  async function () {
+  Task.async(function* () {
     return ChromeUtils.saveHeapSnapshot({ runtime: true });
-  }, "saveHeapSnapshot");
+  }), "saveHeapSnapshot");
 
 StubbedMemoryFront.prototype.startRecordingAllocations = expectState("attached",
-  async function () {
+  Task.async(function* () {
     this.recordingAllocations = true;
-  });
+  }));
 
 StubbedMemoryFront.prototype.stopRecordingAllocations = expectState("attached",
-  async function () {
+  Task.async(function* () {
     this.recordingAllocations = false;
-  });
+  }));
 
 function waitUntilSnapshotState(store, expected) {
   let predicate = () => {
@@ -119,11 +120,11 @@ function waitUntilCensusState(store, getCensus, expected) {
   return waitUntilState(store, predicate);
 }
 
-async function createTempFile() {
+function* createTempFile() {
   let file = FileUtils.getFile("TmpD", ["tmp.fxsnapshot"]);
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, FileUtils.PERMS_FILE);
   let destPath = file.path;
-  let stat = await OS.File.stat(destPath);
+  let stat = yield OS.File.stat(destPath);
   ok(stat.size === 0, "new file is 0 bytes at start");
   return destPath;
 }
diff --git a/devtools/client/memory/test/unit/test_action-clear-snapshots_01.js b/devtools/client/memory/test/unit/test_action-clear-snapshots_01.js
index cbc880ecc407..47635a9b23d2 100644
--- a/devtools/client/memory/test/unit/test_action-clear-snapshots_01.js
+++ b/devtools/client/memory/test/unit/test_action-clear-snapshots_01.js
@@ -9,15 +9,15 @@ let { takeSnapshotAndCensus, clearSnapshots } = require("devtools/client/memory/
 let { actions } = require("devtools/client/memory/constants");
 const { treeMapState } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
+  yield waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
   ok(true, "snapshot created");
 
   ok(true, "dispatch clearSnapshots action");
@@ -26,11 +26,11 @@ add_task(async function () {
     waitUntilAction(store, actions.DELETE_SNAPSHOTS_END)
   ]);
   dispatch(clearSnapshots(heapWorker));
-  await deleteEvents;
+  yield deleteEvents;
   ok(true, "received delete snapshots events");
 
   equal(getState().snapshots.length, 0, "no snapshot remaining");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-clear-snapshots_02.js b/devtools/client/memory/test/unit/test_action-clear-snapshots_02.js
index b2ef780512f2..7cd6984c5972 100644
--- a/devtools/client/memory/test/unit/test_action-clear-snapshots_02.js
+++ b/devtools/client/memory/test/unit/test_action-clear-snapshots_02.js
@@ -8,10 +8,10 @@
 let { takeSnapshotAndCensus, clearSnapshots, takeSnapshot } = require("devtools/client/memory/actions/snapshot");
 let { snapshotState: states, treeMapState, actions } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -19,8 +19,8 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   ok(true, "create a snapshot in SAVED state");
   dispatch(takeSnapshot(front));
-  await waitUntilSnapshotState(store, [states.SAVED, states.SAVED]);
-  await waitUntilCensusState(store, snapshot => snapshot.treeMap,
+  yield waitUntilSnapshotState(store, [states.SAVED, states.SAVED]);
+  yield waitUntilCensusState(store, snapshot => snapshot.treeMap,
                              [treeMapState.SAVED, null]);
   ok(true, "snapshots created with expected states");
 
@@ -30,7 +30,7 @@ add_task(async function () {
     waitUntilAction(store, actions.DELETE_SNAPSHOTS_END)
   ]);
   dispatch(clearSnapshots(heapWorker));
-  await deleteEvents;
+  yield deleteEvents;
   ok(true, "received delete snapshots events");
 
   equal(getState().snapshots.length, 1, "one snapshot remaining");
@@ -41,5 +41,5 @@ add_task(async function () {
     "remaining snapshot doesn't have a census property");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-clear-snapshots_03.js b/devtools/client/memory/test/unit/test_action-clear-snapshots_03.js
index 027f6c9da25e..ba97ec5de898 100644
--- a/devtools/client/memory/test/unit/test_action-clear-snapshots_03.js
+++ b/devtools/client/memory/test/unit/test_action-clear-snapshots_03.js
@@ -8,25 +8,25 @@
 let { takeSnapshotAndCensus, clearSnapshots } = require("devtools/client/memory/actions/snapshot");
 let { snapshotState: states, treeMapState, actions } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
   ok(true, "create a snapshot with a treeMap");
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilSnapshotState(store, [states.SAVED]);
+  yield waitUntilSnapshotState(store, [states.SAVED]);
   ok(true, "snapshot created with a SAVED state");
-  await waitUntilCensusState(store, snapshot => snapshot.treeMap,
+  yield waitUntilCensusState(store, snapshot => snapshot.treeMap,
                              [treeMapState.SAVED]);
   ok(true, "treeMap created with a SAVED state");
 
   ok(true, "set snapshot state to error");
   let id = getState().snapshots[0].id;
   dispatch({ type: actions.SNAPSHOT_ERROR, id, error: new Error("_") });
-  await waitUntilSnapshotState(store, [states.ERROR]);
+  yield waitUntilSnapshotState(store, [states.ERROR]);
   ok(true, "snapshot set to error state");
 
   ok(true, "dispatch clearSnapshots action");
@@ -35,10 +35,10 @@ add_task(async function () {
     waitUntilAction(store, actions.DELETE_SNAPSHOTS_END)
   ]);
   dispatch(clearSnapshots(heapWorker));
-  await deleteEvents;
+  yield deleteEvents;
   ok(true, "received delete snapshots events");
   equal(getState().snapshots.length, 0, "error snapshot deleted");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-clear-snapshots_04.js b/devtools/client/memory/test/unit/test_action-clear-snapshots_04.js
index 536baf83d690..70c90b4b856d 100644
--- a/devtools/client/memory/test/unit/test_action-clear-snapshots_04.js
+++ b/devtools/client/memory/test/unit/test_action-clear-snapshots_04.js
@@ -8,10 +8,10 @@
 let { takeSnapshotAndCensus, clearSnapshots } = require("devtools/client/memory/actions/snapshot");
 let { snapshotState: states, actions, treeMapState } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -19,14 +19,14 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.treeMap,
+  yield waitUntilCensusState(store, snapshot => snapshot.treeMap,
     [treeMapState.SAVED, treeMapState.SAVED, treeMapState.SAVED]);
   ok(true, "snapshots created with a saved census");
 
   ok(true, "set first snapshot state to error");
   let id = getState().snapshots[0].id;
   dispatch({ type: actions.SNAPSHOT_ERROR, id, error: new Error("_") });
-  await waitUntilSnapshotState(store,
+  yield waitUntilSnapshotState(store,
     [states.ERROR, states.READ, states.READ]);
   ok(true, "first snapshot set to error state");
 
@@ -36,11 +36,11 @@ add_task(async function () {
     waitUntilAction(store, actions.DELETE_SNAPSHOTS_END)
   ]);
   dispatch(clearSnapshots(heapWorker));
-  await deleteEvents;
+  yield deleteEvents;
   ok(true, "received delete snapshots events");
 
   equal(getState().snapshots.length, 0, "no snapshot remaining");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-clear-snapshots_05.js b/devtools/client/memory/test/unit/test_action-clear-snapshots_05.js
index fce1af5a7358..b5c579341584 100644
--- a/devtools/client/memory/test/unit/test_action-clear-snapshots_05.js
+++ b/devtools/client/memory/test/unit/test_action-clear-snapshots_05.js
@@ -8,10 +8,10 @@
 let { takeSnapshotAndCensus, clearSnapshots } = require("devtools/client/memory/actions/snapshot");
 let { actions, treeMapState } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -19,7 +19,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   ok(true, "snapshots created with a saved census");
-  await waitUntilCensusState(store, snapshot => snapshot.treeMap,
+  yield waitUntilCensusState(store, snapshot => snapshot.treeMap,
                              [treeMapState.SAVED, treeMapState.SAVED]);
 
   let errorHeapWorker = {
@@ -36,10 +36,10 @@ add_task(async function () {
     waitUntilAction(store, actions.SNAPSHOT_ERROR),
   ]);
   dispatch(clearSnapshots(errorHeapWorker));
-  await deleteEvents;
+  yield deleteEvents;
   ok(true, "received delete snapshots and snapshot error events");
   equal(getState().snapshots.length, 0, "no snapshot remaining");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-clear-snapshots_06.js b/devtools/client/memory/test/unit/test_action-clear-snapshots_06.js
index 44858a6cc7c1..889c49e32f5f 100644
--- a/devtools/client/memory/test/unit/test_action-clear-snapshots_06.js
+++ b/devtools/client/memory/test/unit/test_action-clear-snapshots_06.js
@@ -18,17 +18,17 @@ const {
   selectSnapshotForDiffingAndRefresh
 } = require("devtools/client/memory/actions/diffing");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
   ok(true, "create 2 snapshots with a saved census");
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.treeMap,
+  yield waitUntilCensusState(store, snapshot => snapshot.treeMap,
                              [treeMapState.SAVED, treeMapState.SAVED]);
   ok(true, "snapshots created with a saved census");
 
@@ -40,7 +40,7 @@ add_task(async function () {
 
   ok(getState().diffing, "We should be in diffing view");
 
-  await waitUntilAction(store, actions.TAKE_CENSUS_DIFF_END);
+  yield waitUntilAction(store, actions.TAKE_CENSUS_DIFF_END);
   ok(true, "Received TAKE_CENSUS_DIFF_END action");
 
   ok(true, "Dispatch clearSnapshots action");
@@ -49,12 +49,12 @@ add_task(async function () {
     waitUntilAction(store, actions.DELETE_SNAPSHOTS_END)
   ]);
   dispatch(clearSnapshots(heapWorker));
-  await deleteEvents;
+  yield deleteEvents;
   ok(true, "received delete snapshots events");
 
   ok(getState().snapshots.length === 0, "Snapshots array should be empty");
   ok(!getState().diffing, "We should no longer be diffing");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-export-snapshot.js b/devtools/client/memory/test/unit/test_action-export-snapshot.js
index 6a13fdb58a99..a26869dfb2ee 100644
--- a/devtools/client/memory/test/unit/test_action-export-snapshot.js
+++ b/devtools/client/memory/test/unit/test_action-export-snapshot.js
@@ -9,16 +9,16 @@ let { exportSnapshot } = require("devtools/client/memory/actions/io");
 let { takeSnapshotAndCensus } = require("devtools/client/memory/actions/snapshot");
 let { actions, treeMapState } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
-  let destPath = await createTempFile();
+  let destPath = yield createTempFile();
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.treeMap,
+  yield waitUntilCensusState(store, snapshot => snapshot.treeMap,
                              [treeMapState.SAVED]);
 
   let exportEvents = Promise.all([
@@ -26,12 +26,12 @@ add_task(async function () {
     waitUntilAction(store, actions.EXPORT_SNAPSHOT_END)
   ]);
   dispatch(exportSnapshot(getState().snapshots[0], destPath));
-  await exportEvents;
+  yield exportEvents;
 
-  let stat = await OS.File.stat(destPath);
+  let stat = yield OS.File.stat(destPath);
   info(stat.size);
   ok(stat.size > 0, "destination file is more than 0 bytes");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-filter-02.js b/devtools/client/memory/test/unit/test_action-filter-02.js
index 11f7549d3257..f69201ba3051 100644
--- a/devtools/client/memory/test/unit/test_action-filter-02.js
+++ b/devtools/client/memory/test/unit/test_action-filter-02.js
@@ -10,10 +10,10 @@ let { setFilterStringAndRefresh } = require("devtools/client/memory/actions/filt
 let { takeSnapshotAndCensus, selectSnapshotAndRefresh } = require("devtools/client/memory/actions/snapshot");
 let { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -25,18 +25,18 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
   ok(true, "saved 3 snapshots and took a census of each of them");
 
   dispatch(setFilterStringAndRefresh("str", heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVING]);
   ok(true, "setting filter string should recompute the selected snapshot's census");
 
   equal(getState().filter, "str", "now inverted");
 
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
 
   equal(getState().snapshots[0].census.filter, null);
@@ -44,11 +44,11 @@ add_task(async function () {
   equal(getState().snapshots[2].census.filter, "str");
 
   dispatch(selectSnapshotAndRefresh(heapWorker, getState().snapshots[1].id));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVING, censusState.SAVED]);
   ok(true, "selecting non-inverted census should trigger a recompute");
 
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
 
   equal(getState().snapshots[0].census.filter, null);
@@ -56,5 +56,5 @@ add_task(async function () {
   equal(getState().snapshots[2].census.filter, "str");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-filter-03.js b/devtools/client/memory/test/unit/test_action-filter-03.js
index 51fced580160..23fa6d5cdb50 100644
--- a/devtools/client/memory/test/unit/test_action-filter-03.js
+++ b/devtools/client/memory/test/unit/test_action-filter-03.js
@@ -11,21 +11,21 @@ let { setFilterString, setFilterStringAndRefresh } = require("devtools/client/me
 let { takeSnapshotAndCensus } = require("devtools/client/memory/actions/snapshot");
 let { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(changeView(viewState.CENSUS));
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilSnapshotState(store, [states.SAVING]);
+  yield waitUntilSnapshotState(store, [states.SAVING]);
 
   dispatch(setFilterString("str"));
 
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED]);
   equal(getState().filter, "str",
         "should want filtered trees");
@@ -33,18 +33,18 @@ add_task(async function () {
         "snapshot-we-were-in-the-middle-of-saving's census should be filtered");
 
   dispatch(setFilterStringAndRefresh("", heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVING]);
   ok(true, "changing filter string retriggers census");
   ok(!getState().filter, "no longer filtering");
 
   dispatch(setFilterString("obj"));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED]);
   equal(getState().filter, "obj", "filtering for obj now");
   equal(getState().snapshots[0].census.filter, "obj",
         "census-we-were-in-the-middle-of-recomputing should be filtered again");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-import-snapshot-and-census.js b/devtools/client/memory/test/unit/test_action-import-snapshot-and-census.js
index 7a3d370c8581..182cc8ea6f49 100644
--- a/devtools/client/memory/test/unit/test_action-import-snapshot-and-census.js
+++ b/devtools/client/memory/test/unit/test_action-import-snapshot-and-census.js
@@ -12,23 +12,23 @@ let { actions, snapshotState: states, treeMapState } = require("devtools/client/
 let { exportSnapshot, importSnapshotAndCensus } = require("devtools/client/memory/actions/io");
 let { takeSnapshotAndCensus } = require("devtools/client/memory/actions/snapshot");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { subscribe, dispatch, getState } = store;
 
-  let destPath = await createTempFile();
+  let destPath = yield createTempFile();
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
+  yield waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
 
   let exportEvents = Promise.all([
     waitUntilAction(store, actions.EXPORT_SNAPSHOT_START),
     waitUntilAction(store, actions.EXPORT_SNAPSHOT_END)
   ]);
   dispatch(exportSnapshot(getState().snapshots[0], destPath));
-  await exportEvents;
+  yield exportEvents;
 
   // Now import our freshly exported snapshot
   let snapshotI = 0;
@@ -58,7 +58,7 @@ add_task(async function () {
   let unsubscribe = subscribe(expectStates);
   dispatch(importSnapshotAndCensus(heapWorker, destPath));
 
-  await waitUntilState(store, () => {
+  yield waitUntilState(store, () => {
     return snapshotI === snapshotStates.length &&
            censusI === censusStates.length;
   });
diff --git a/devtools/client/memory/test/unit/test_action-import-snapshot-dominator-tree.js b/devtools/client/memory/test/unit/test_action-import-snapshot-dominator-tree.js
index 9f770d280d73..d0c367f7dfd3 100644
--- a/devtools/client/memory/test/unit/test_action-import-snapshot-dominator-tree.js
+++ b/devtools/client/memory/test/unit/test_action-import-snapshot-dominator-tree.js
@@ -14,10 +14,10 @@ let { snapshotState, dominatorTreeState, viewState, treeMapState } =
 let { importSnapshotAndCensus } = require("devtools/client/memory/actions/io");
 let { changeViewAndRefresh } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { subscribe, dispatch, getState } = store;
 
@@ -45,10 +45,10 @@ add_task(async function () {
   };
 
   let unsubscribe = subscribe(expectStates);
-  const snapshotPath = await front.saveHeapSnapshot();
+  const snapshotPath = yield front.saveHeapSnapshot();
   dispatch(importSnapshotAndCensus(heapWorker, snapshotPath));
 
-  await waitUntilState(store, () => i === expected.length);
+  yield waitUntilState(store, () => i === expected.length);
   unsubscribe();
   equal(i, expected.length, "importSnapshotAndCensus() produces the correct " +
     "sequence of states in a snapshot");
diff --git a/devtools/client/memory/test/unit/test_action-select-snapshot.js b/devtools/client/memory/test/unit/test_action-select-snapshot.js
index fa54b3fbc6a4..d257d78ddd47 100644
--- a/devtools/client/memory/test/unit/test_action-select-snapshot.js
+++ b/devtools/client/memory/test/unit/test_action-select-snapshot.js
@@ -10,22 +10,22 @@
 let actions = require("devtools/client/memory/actions/snapshot");
 let { snapshotState: states } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
-  await front.attach();
+  yield front.attach();
   let store = Store();
 
   for (let i = 0; i < 5; i++) {
     store.dispatch(actions.takeSnapshot(front));
   }
 
-  await waitUntilState(store,
+  yield waitUntilState(store,
     ({ snapshots }) => snapshots.length === 5 && snapshots.every(isDone));
 
   for (let i = 0; i < 5; i++) {
     info(`Selecting snapshot[${i}]`);
     store.dispatch(actions.selectSnapshot(store.getState().snapshots[i].id));
-    await waitUntilState(store, ({ snapshots }) => snapshots[i].selected);
+    yield waitUntilState(store, ({ snapshots }) => snapshots[i].selected);
 
     let { snapshots } = store.getState();
     ok(snapshots[i].selected, `snapshot[${i}] selected`);
diff --git a/devtools/client/memory/test/unit/test_action-set-display-and-refresh-01.js b/devtools/client/memory/test/unit/test_action-set-display-and-refresh-01.js
index addebaee724d..159262c7321c 100644
--- a/devtools/client/memory/test/unit/test_action-set-display-and-refresh-01.js
+++ b/devtools/client/memory/test/unit/test_action-set-display-and-refresh-01.js
@@ -18,10 +18,10 @@ const { changeView } = require("devtools/client/memory/actions/view");
 // We test setting an invalid display, which triggers an assertion failure.
 EXPECTED_DTU_ASSERT_FAILURE_COUNT = 1;
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -38,7 +38,7 @@ add_task(async function () {
   // Test invalid displays
   ok(getState().errors.length === 0, "No error actions in the queue.");
   dispatch(setCensusDisplayAndRefresh(heapWorker, {}));
-  await waitUntilState(store, () => getState().errors.length === 1);
+  yield waitUntilState(store, () => getState().errors.length === 1);
   ok(true, "Emits an error action when passing in an invalid display object");
 
   equal(getState().censusDisplay.breakdown.by, "allocationStack",
@@ -46,7 +46,7 @@ add_task(async function () {
 
   // Test new snapshots
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED]);
 
   equal(getState().snapshots[0].census.display, censusDisplays.allocationStack,
@@ -54,10 +54,10 @@ add_task(async function () {
 
   // Updates when changing display during `SAVING`
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVING]);
   dispatch(setCensusDisplayAndRefresh(heapWorker, censusDisplays.coarseType));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED]);
   equal(getState().snapshots[1].census.display, censusDisplays.coarseType,
         "Changing display while saving a snapshot results " +
@@ -65,10 +65,10 @@ add_task(async function () {
 
   // Updates when changing display during `SAVING_CENSUS`
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVING]);
   dispatch(setCensusDisplayAndRefresh(heapWorker, censusDisplays.allocationStack));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
   equal(getState().snapshots[2].census.display, censusDisplays.allocationStack,
         "Display can be changed while saving census, stores updated display in snapshot");
@@ -76,16 +76,16 @@ add_task(async function () {
   // Updates census on currently selected snapshot when changing display
   ok(getState().snapshots[2].selected, "Third snapshot currently selected");
   dispatch(setCensusDisplayAndRefresh(heapWorker, censusDisplays.coarseType));
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state => state.snapshots[2].census.state === censusState.SAVING);
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state => state.snapshots[2].census.state === censusState.SAVED);
   equal(getState().snapshots[2].census.display, censusDisplays.coarseType,
         "Snapshot census updated when changing displays " +
         "after already generating one census");
 
   dispatch(setCensusDisplayAndRefresh(heapWorker, censusDisplays.allocationStack));
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state => state.snapshots[2].census.state === censusState.SAVED);
   equal(getState().snapshots[2].census.display, censusDisplays.allocationStack,
         "Snapshot census updated when changing displays " +
@@ -99,9 +99,9 @@ add_task(async function () {
 
   // Updates to current display when switching to stale snapshot.
   dispatch(selectSnapshotAndRefresh(heapWorker, getState().snapshots[1].id));
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVING, censusState.SAVED]);
-  await waitUntilCensusState(store, snapshot => snapshot.census,
+  yield waitUntilCensusState(store, snapshot => snapshot.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
 
   ok(getState().snapshots[1].selected, "Second snapshot selected currently");
@@ -109,5 +109,5 @@ add_task(async function () {
         "Second snapshot using `allocationStack` display and updated to correct display");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-set-display-and-refresh-02.js b/devtools/client/memory/test/unit/test_action-set-display-and-refresh-02.js
index 567c414d67c4..1146f1e8767d 100644
--- a/devtools/client/memory/test/unit/test_action-set-display-and-refresh-02.js
+++ b/devtools/client/memory/test/unit/test_action-set-display-and-refresh-02.js
@@ -23,10 +23,10 @@ let CUSTOM = {
   }
 };
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -36,7 +36,7 @@ add_task(async function () {
         "CUSTOM display stored in display state.");
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   equal(getState().snapshots[0].census.display, CUSTOM,
   "New snapshot stored CUSTOM display when done taking census");
diff --git a/devtools/client/memory/test/unit/test_action-set-display.js b/devtools/client/memory/test/unit/test_action-set-display.js
index bea4c4c3d4cb..be555087c986 100644
--- a/devtools/client/memory/test/unit/test_action-set-display.js
+++ b/devtools/client/memory/test/unit/test_action-set-display.js
@@ -17,10 +17,10 @@ const { changeView } = require("devtools/client/memory/actions/view");
 // We test setting an invalid display, which triggers an assertion failure.
 EXPECTED_DTU_ASSERT_FAILURE_COUNT = 1;
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -46,7 +46,7 @@ add_task(async function () {
 
   // Test new snapshots
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
   equal(getState().snapshots[0].census.display, censusDisplays.allocationStack,
         "New snapshots use the current, non-default display");
 });
diff --git a/devtools/client/memory/test/unit/test_action-take-census.js b/devtools/client/memory/test/unit/test_action-take-census.js
index 256e2d7639cc..9da57d1104a1 100644
--- a/devtools/client/memory/test/unit/test_action-take-census.js
+++ b/devtools/client/memory/test/unit/test_action-take-census.js
@@ -15,16 +15,16 @@ var { changeView } = require("devtools/client/memory/actions/view");
 // triggers an assertion failure.
 EXPECTED_DTU_ASSERT_FAILURE_COUNT = 1;
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
 
   store.dispatch(changeView(viewState.CENSUS));
 
   store.dispatch(actions.takeSnapshot(front));
-  await waitUntilState(store, () => {
+  yield waitUntilState(store, () => {
     let snapshots = store.getState().snapshots;
     return snapshots.length === 1 && snapshots[0].state === states.SAVED;
   });
@@ -34,18 +34,18 @@ add_task(async function () {
 
   // Test error case of wrong state.
   store.dispatch(actions.takeCensus(heapWorker, snapshot.id));
-  await waitUntilState(store, () => store.getState().errors.length === 1);
+  yield waitUntilState(store, () => store.getState().errors.length === 1);
 
   dumpn("Found error: " + store.getState().errors[0]);
   ok(/Assertion failure/.test(store.getState().errors[0]),
     "Error thrown when taking a census of a snapshot that has not been read.");
 
   store.dispatch(actions.readSnapshot(heapWorker, snapshot.id));
-  await waitUntilState(store, () => store.getState().snapshots[0].state === states.READ);
+  yield waitUntilState(store, () => store.getState().snapshots[0].state === states.READ);
 
   store.dispatch(actions.takeCensus(heapWorker, snapshot.id));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVING]);
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVING]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   snapshot = store.getState().snapshots[0];
   ok(snapshot.census, "Snapshot has census after saved census");
diff --git a/devtools/client/memory/test/unit/test_action-take-snapshot-and-census.js b/devtools/client/memory/test/unit/test_action-take-snapshot-and-census.js
index 53b87cb277d5..bb300719a92e 100644
--- a/devtools/client/memory/test/unit/test_action-take-snapshot-and-census.js
+++ b/devtools/client/memory/test/unit/test_action-take-snapshot-and-census.js
@@ -11,10 +11,10 @@
 let { snapshotState: states, treeMapState } = require("devtools/client/memory/constants");
 let actions = require("devtools/client/memory/actions/snapshot");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
 
   let snapshotI = 0;
@@ -44,7 +44,7 @@ add_task(async function () {
   let unsubscribe = store.subscribe(expectStates);
   store.dispatch(actions.takeSnapshotAndCensus(front, heapWorker));
 
-  await waitUntilState(store, () => {
+  yield waitUntilState(store, () => {
     return snapshotI === snapshotStates.length &&
            censusI === censusStates.length;
   });
diff --git a/devtools/client/memory/test/unit/test_action-take-snapshot.js b/devtools/client/memory/test/unit/test_action-take-snapshot.js
index a246c17d532e..f344edcb3287 100644
--- a/devtools/client/memory/test/unit/test_action-take-snapshot.js
+++ b/devtools/client/memory/test/unit/test_action-take-snapshot.js
@@ -10,9 +10,9 @@
 let actions = require("devtools/client/memory/actions/snapshot");
 let { snapshotState: states } = require("devtools/client/memory/constants");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
-  await front.attach();
+  yield front.attach();
   let store = Store();
 
   let unsubscribe = store.subscribe(checkState);
@@ -41,7 +41,7 @@ add_task(async function () {
 
   for (let i = 0; i < 4; i++) {
     store.dispatch(actions.takeSnapshot(front));
-    await waitUntilState(store, () => foundPendingState && foundDoneState);
+    yield waitUntilState(store, () => foundPendingState && foundDoneState);
 
     // reset state trackers
     foundDoneState = foundPendingState = false;
diff --git a/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-01.js b/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-01.js
index 69fea4c666e7..3f3459c7c8bc 100644
--- a/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-01.js
+++ b/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-01.js
@@ -20,10 +20,10 @@ const {
 } = require("devtools/client/memory/actions/snapshot");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -37,7 +37,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
   ok(true, "saved 3 snapshots and took a census of each of them");
 
@@ -45,13 +45,13 @@ add_task(async function () {
   dispatch(setCensusDisplayAndRefresh(heapWorker,
                                       censusDisplays.invertedAllocationStack));
 
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVING]);
   ok(true, "toggling inverted should recompute the selected snapshot's census");
 
   equal(getState().censusDisplay.inverted, true, "now inverted");
 
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
 
   equal(getState().snapshots[0].census.display.inverted, false);
@@ -59,11 +59,11 @@ add_task(async function () {
   equal(getState().snapshots[2].census.display.inverted, true);
 
   dispatch(selectSnapshotAndRefresh(heapWorker, getState().snapshots[1].id));
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
                              [censusState.SAVED, censusState.SAVING, censusState.SAVED]);
   ok(true, "selecting non-inverted census should trigger a recompute");
 
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
                              [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
 
   equal(getState().snapshots[0].census.display.inverted, false);
@@ -71,5 +71,5 @@ add_task(async function () {
   equal(getState().snapshots[2].census.display.inverted, true);
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-02.js b/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-02.js
index 6e63d0476b93..c5f594f7baac 100644
--- a/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-02.js
+++ b/devtools/client/memory/test/unit/test_action-toggle-inverted-and-refresh-02.js
@@ -14,10 +14,10 @@ const {
 } = require("devtools/client/memory/actions/census-display");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -28,12 +28,12 @@ add_task(async function () {
         "Should not have an inverted census display");
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilSnapshotState(store, [states.SAVING]);
+  yield waitUntilSnapshotState(store, [states.SAVING]);
 
   dispatch(setCensusDisplayAndRefresh(heapWorker,
                                       censusDisplays.invertedAllocationStack));
 
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   ok(getState().censusDisplay.inverted,
      "should want inverted trees");
@@ -41,17 +41,17 @@ add_task(async function () {
      "snapshot-we-were-in-the-middle-of-saving's census should be inverted");
 
   dispatch(setCensusDisplayAndRefresh(heapWorker, censusDisplays.allocationStack));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVING]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVING]);
   ok(true, "toggling inverted retriggers census");
   ok(!getState().censusDisplay.inverted, "no longer inverted");
 
   dispatch(setCensusDisplayAndRefresh(heapWorker,
                                       censusDisplays.invertedAllocationStack));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
   ok(getState().censusDisplay.inverted, "inverted again");
   ok(getState().snapshots[0].census.display.inverted,
      "census-we-were-in-the-middle-of-recomputing should be inverted again");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action-toggle-recording-allocations.js b/devtools/client/memory/test/unit/test_action-toggle-recording-allocations.js
index a4d73a502c11..ec3795016052 100644
--- a/devtools/client/memory/test/unit/test_action-toggle-recording-allocations.js
+++ b/devtools/client/memory/test/unit/test_action-toggle-recording-allocations.js
@@ -9,9 +9,9 @@
 
 let { toggleRecordingAllocationStacks } = require("devtools/client/memory/actions/allocations");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -20,20 +20,20 @@ add_task(async function () {
         "not in the process of toggling by default");
 
   dispatch(toggleRecordingAllocationStacks(front));
-  await waitUntilState(store, () => getState().allocations.togglingInProgress);
+  yield waitUntilState(store, () => getState().allocations.togglingInProgress);
   ok(true, "`togglingInProgress` set to true when toggling on");
-  await waitUntilState(store, () => !getState().allocations.togglingInProgress);
+  yield waitUntilState(store, () => !getState().allocations.togglingInProgress);
 
   equal(getState().allocations.recording, true, "now we are recording");
   ok(front.recordingAllocations, "front is recording too");
 
   dispatch(toggleRecordingAllocationStacks(front));
-  await waitUntilState(store, () => getState().allocations.togglingInProgress);
+  yield waitUntilState(store, () => getState().allocations.togglingInProgress);
   ok(true, "`togglingInProgress` set to true when toggling off");
-  await waitUntilState(store, () => !getState().allocations.togglingInProgress);
+  yield waitUntilState(store, () => !getState().allocations.togglingInProgress);
 
   equal(getState().allocations.recording, false, "now we are not recording");
   ok(front.recordingAllocations, "front is not recording anymore");
 
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action_diffing_01.js b/devtools/client/memory/test/unit/test_action_diffing_01.js
index dc29b12f0834..d62fbf8743e8 100644
--- a/devtools/client/memory/test/unit/test_action_diffing_01.js
+++ b/devtools/client/memory/test/unit/test_action_diffing_01.js
@@ -7,10 +7,10 @@
 
 const { toggleDiffing } = require("devtools/client/memory/actions/diffing");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -23,5 +23,5 @@ add_task(async function () {
   equal(getState().diffing, null, "not diffing again after toggling again");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action_diffing_02.js b/devtools/client/memory/test/unit/test_action_diffing_02.js
index 944f3392b0c3..6ba9d4ec4447 100644
--- a/devtools/client/memory/test/unit/test_action_diffing_02.js
+++ b/devtools/client/memory/test/unit/test_action_diffing_02.js
@@ -10,10 +10,10 @@ const { toggleDiffing } = require("devtools/client/memory/actions/diffing");
 const { takeSnapshotAndCensus } = require("devtools/client/memory/actions/snapshot");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -24,7 +24,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
     [censusState.SAVED, censusState.SAVED, censusState.SAVED]);
 
   ok(getState().snapshots.some(s => s.selected),
@@ -39,5 +39,5 @@ add_task(async function () {
   }
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action_diffing_03.js b/devtools/client/memory/test/unit/test_action_diffing_03.js
index 96e91817f7d5..87244d792ab3 100644
--- a/devtools/client/memory/test/unit/test_action_diffing_03.js
+++ b/devtools/client/memory/test/unit/test_action_diffing_03.js
@@ -18,10 +18,10 @@ const { changeView } = require("devtools/client/memory/actions/view");
 // trigger assertion failures.
 EXPECTED_DTU_ASSERT_FAILURE_COUNT = 2;
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -32,7 +32,7 @@ add_task(async function () {
   dispatch(takeSnapshot(front, heapWorker));
   dispatch(takeSnapshot(front, heapWorker));
 
-  await waitUntilSnapshotState(store,
+  yield waitUntilSnapshotState(store,
         [snapshotState.SAVED, snapshotState.SAVED, snapshotState.SAVED]);
   dispatch(takeSnapshot(front));
 
@@ -97,5 +97,5 @@ add_task(async function () {
   ok(threw, "Can't select more than two snapshots for diffing");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action_diffing_04.js b/devtools/client/memory/test/unit/test_action_diffing_04.js
index 5d1f396b6c58..735a734150af 100644
--- a/devtools/client/memory/test/unit/test_action_diffing_04.js
+++ b/devtools/client/memory/test/unit/test_action_diffing_04.js
@@ -20,23 +20,23 @@ const {
 } = require("devtools/client/memory/actions/snapshot");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
   dispatch(changeView(viewState.CENSUS));
 
   equal(getState().diffing, null, "not diffing by default");
 
-  const s1 = await dispatch(takeSnapshot(front, heapWorker));
-  const s2 = await dispatch(takeSnapshot(front, heapWorker));
-  const s3 = await dispatch(takeSnapshot(front, heapWorker));
+  const s1 = yield dispatch(takeSnapshot(front, heapWorker));
+  const s2 = yield dispatch(takeSnapshot(front, heapWorker));
+  const s3 = yield dispatch(takeSnapshot(front, heapWorker));
   dispatch(readSnapshot(heapWorker, s1));
   dispatch(readSnapshot(heapWorker, s2));
   dispatch(readSnapshot(heapWorker, s3));
-  await waitUntilSnapshotState(store,
+  yield waitUntilSnapshotState(store,
     [snapshotState.READ, snapshotState.READ, snapshotState.READ]);
 
   dispatch(toggleDiffing());
@@ -51,13 +51,13 @@ add_task(async function () {
   equal(getState().diffing.secondSnapshotId, getState().snapshots[1].id,
         "Second snapshot selected.");
 
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state =>
                          state.diffing.state === diffingState.TAKING_DIFF);
   ok(true,
      "Selecting two snapshots for diffing should trigger computing a diff.");
 
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state => state.diffing.state === diffingState.TOOK_DIFF);
   ok(true, "And then the diff should complete.");
   ok(getState().diffing.census, "And we should have a census.");
@@ -71,5 +71,5 @@ add_task(async function () {
         "And that census should have the correct inversion");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_action_diffing_05.js b/devtools/client/memory/test/unit/test_action_diffing_05.js
index 201d24960a4d..74e47badee15 100644
--- a/devtools/client/memory/test/unit/test_action_diffing_05.js
+++ b/devtools/client/memory/test/unit/test_action_diffing_05.js
@@ -27,36 +27,36 @@ const {
 } = require("devtools/client/memory/actions/snapshot");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
   dispatch(changeView(viewState.CENSUS));
 
-  await dispatch(setCensusDisplayAndRefresh(heapWorker,
+  yield dispatch(setCensusDisplayAndRefresh(heapWorker,
                                         censusDisplays.allocationStack));
   equal(getState().censusDisplay.inverted, false,
         "not inverted at start");
 
   equal(getState().diffing, null, "not diffing by default");
 
-  const s1 = await dispatch(takeSnapshot(front, heapWorker));
-  const s2 = await dispatch(takeSnapshot(front, heapWorker));
-  const s3 = await dispatch(takeSnapshot(front, heapWorker));
+  const s1 = yield dispatch(takeSnapshot(front, heapWorker));
+  const s2 = yield dispatch(takeSnapshot(front, heapWorker));
+  const s3 = yield dispatch(takeSnapshot(front, heapWorker));
   dispatch(readSnapshot(heapWorker, s1));
   dispatch(readSnapshot(heapWorker, s2));
   dispatch(readSnapshot(heapWorker, s3));
-  await waitUntilSnapshotState(store,
+  yield waitUntilSnapshotState(store,
     [snapshotState.READ, snapshotState.READ, snapshotState.READ]);
 
-  await dispatch(toggleDiffing());
+  yield dispatch(toggleDiffing());
   dispatch(selectSnapshotForDiffingAndRefresh(heapWorker,
                                               getState().snapshots[0]));
   dispatch(selectSnapshotForDiffingAndRefresh(heapWorker,
                                               getState().snapshots[1]));
-  await waitUntilState(store,
+  yield waitUntilState(store,
                        state => state.diffing.state === diffingState.TOOK_DIFF);
 
   const shouldTriggerRecompute = [
@@ -82,12 +82,12 @@ add_task(async function () {
     dumpn(`Testing that "${name}" triggers a diff recompute`);
     func();
 
-    await waitUntilState(store,
+    yield waitUntilState(store,
                          state =>
                            state.diffing.state === diffingState.TAKING_DIFF);
     ok(true, "triggered diff recompute.");
 
-    await waitUntilState(store,
+    yield waitUntilState(store,
                          state =>
                            state.diffing.state === diffingState.TOOK_DIFF);
     ok(true, "And then the diff should complete.");
@@ -105,5 +105,5 @@ add_task(async function () {
   }
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_01.js b/devtools/client/memory/test/unit/test_dominator_trees_01.js
index b92e445a01ed..8044a5543849 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_01.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_01.js
@@ -14,15 +14,15 @@ let {
   computeAndFetchDominatorTree,
 } = require("devtools/client/memory/actions/snapshot");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
+  yield waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
   ok(!getState().snapshots[0].dominatorTree,
      "There shouldn't be a dominator tree model yet since it is not computed " +
      "until we switch to the dominators view.");
@@ -33,26 +33,26 @@ add_task(async function () {
      "Should now have a dominator tree model for the selected snapshot");
 
   // Wait for the dominator tree to start being computed.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.COMPUTING);
   ok(true, "The dominator tree started computing");
   ok(!getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is computing, we should not have its root");
 
   // Wait for the dominator tree to finish computing and start being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
   ok(true, "The dominator tree started fetching");
   ok(!getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is fetching, we should not have its root");
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "The dominator tree was fetched");
   ok(getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is loaded, we should have its root");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_02.js b/devtools/client/memory/test/unit/test_dominator_trees_02.js
index c7bd0854583e..c682964f53d2 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_02.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_02.js
@@ -18,15 +18,15 @@ const {
   changeViewAndRefresh
 } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
+  yield waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
   ok(!getState().snapshots[0].dominatorTree,
      "There shouldn't be a dominator tree model yet since it is not computed " +
      "until we switch to the dominators view.");
@@ -36,26 +36,26 @@ add_task(async function () {
      "Should now have a dominator tree model for the selected snapshot");
 
   // Wait for the dominator tree to start being computed.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.COMPUTING);
   ok(true, "The dominator tree started computing");
   ok(!getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is computing, we should not have its root");
 
   // Wait for the dominator tree to finish computing and start being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
   ok(true, "The dominator tree started fetching");
   ok(!getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is fetching, we should not have its root");
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "The dominator tree was fetched");
   ok(getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is loaded, we should have its root");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_03.js b/devtools/client/memory/test/unit/test_dominator_trees_03.js
index 1274076e175e..7779fdab2703 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_03.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_03.js
@@ -17,10 +17,10 @@ const {
   changeView
 } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -31,7 +31,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
   // Wait for the dominator tree to start being computed.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] && state.snapshots[0].dominatorTree);
   equal(getState().snapshots[0].dominatorTree.state,
         dominatorTreeState.COMPUTING,
@@ -40,19 +40,19 @@ add_task(async function () {
      "When the dominator tree is computing, we should not have its root");
 
   // Wait for the dominator tree to finish computing and start being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
   ok(true, "The dominator tree started fetching");
   ok(!getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is fetching, we should not have its root");
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "The dominator tree was fetched");
   ok(getState().snapshots[0].dominatorTree.root,
      "When the dominator tree is loaded, we should have its root");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_04.js b/devtools/client/memory/test/unit/test_dominator_trees_04.js
index 82ba8767bed0..addd418fb7bb 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_04.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_04.js
@@ -18,10 +18,10 @@ const {
   changeView
 } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
 
   for (let intermediateSnapshotState of [states.SAVING, states.READING, states.READ]) {
     dumpn("Testing switching to the DOMINATOR_TREE view in the middle of the " +
@@ -31,14 +31,14 @@ add_task(async function () {
     let { getState, dispatch } = store;
 
     dispatch(takeSnapshotAndCensus(front, heapWorker));
-    await waitUntilSnapshotState(store, [intermediateSnapshotState]);
+    yield waitUntilSnapshotState(store, [intermediateSnapshotState]);
 
     dispatch(changeView(viewState.DOMINATOR_TREE));
     equal(getState().view.state, viewState.DOMINATOR_TREE,
           "We should now be in the DOMINATOR_TREE view");
 
     // Wait for the dominator tree to start being computed.
-    await waitUntilState(store, state =>
+    yield waitUntilState(store, state =>
       state.snapshots[0] && state.snapshots[0].dominatorTree);
     equal(getState().snapshots[0].dominatorTree.state,
           dominatorTreeState.COMPUTING,
@@ -47,14 +47,14 @@ add_task(async function () {
        "When the dominator tree is computing, we should not have its root");
 
     // Wait for the dominator tree to finish computing and start being fetched.
-    await waitUntilState(store, state =>
+    yield waitUntilState(store, state =>
       state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
     ok(true, "The dominator tree started fetching");
     ok(!getState().snapshots[0].dominatorTree.root,
        "When the dominator tree is fetching, we should not have its root");
 
     // Wait for the dominator tree to finish being fetched.
-    await waitUntilState(store, state =>
+    yield waitUntilState(store, state =>
       state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
     ok(true, "The dominator tree was fetched");
     ok(getState().snapshots[0].dominatorTree.root,
@@ -62,5 +62,5 @@ add_task(async function () {
   }
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_05.js b/devtools/client/memory/test/unit/test_dominator_trees_05.js
index 202a17754c4e..850a0bd80b49 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_05.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_05.js
@@ -18,16 +18,16 @@ let {
 
 let { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap,
+  yield waitUntilCensusState(store, s => s.treeMap,
                              [treeMapState.SAVED, treeMapState.SAVED]);
 
   ok(getState().snapshots[1].selected, "The second snapshot is selected");
@@ -36,7 +36,7 @@ add_task(async function () {
   dispatch(changeView(viewState.DOMINATOR_TREE));
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[1].dominatorTree &&
     state.snapshots[1].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "The second snapshot's dominator tree was fetched");
@@ -46,11 +46,11 @@ add_task(async function () {
 
   // And now the first snapshot should have its dominator tree fetched and
   // computed because of the new selection.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "The first snapshot's dominator tree was fetched");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_06.js b/devtools/client/memory/test/unit/test_dominator_trees_06.js
index b380a86e4fcb..4155c784ce1e 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_06.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_06.js
@@ -18,10 +18,10 @@ const DominatorTreeLazyChildren
 
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -29,7 +29,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
@@ -72,7 +72,7 @@ add_task(async function () {
         "Fetching immediately dominated children should put us in the " +
         "INCREMENTAL_FETCHING state");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true,
      "The dominator tree should go back to LOADED after the incremental " +
@@ -121,5 +121,5 @@ add_task(async function () {
   ok(newNode.children, "And the new node should have the children attached");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_07.js b/devtools/client/memory/test/unit/test_dominator_trees_07.js
index 643749fd6643..52c78bd5f998 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_07.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_07.js
@@ -19,10 +19,10 @@ const DominatorTreeLazyChildren
 
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -30,7 +30,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
@@ -94,7 +94,7 @@ add_task(async function () {
         "Fetching immediately dominated children should put us in the " +
         "INCREMENTAL_FETCHING state");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true,
      "The dominator tree should go back to LOADED after the incremental " +
@@ -138,5 +138,5 @@ add_task(async function () {
      "And the new node should have the new children attached");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_08.js b/devtools/client/memory/test/unit/test_dominator_trees_08.js
index 57625c7a6cd6..87bdacc6bce6 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_08.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_08.js
@@ -22,23 +22,23 @@ const {
   takeSnapshotAndCensus,
 } = require("devtools/client/memory/actions/snapshot");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(changeView(viewState.DOMINATOR_TREE));
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
+  yield waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
   ok(!getState().snapshots[0].dominatorTree,
      "There shouldn't be a dominator tree model yet since it is not computed " +
      "until we switch to the dominators view.");
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
@@ -57,13 +57,13 @@ add_task(async function () {
     heapWorker,
     labelDisplays.allocationStack));
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
   ok(true,
      "switching display types caused the dominator tree to be fetched " +
      "again.");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   equal(getState().snapshots[0].dominatorTree.display,
         labelDisplays.allocationStack,
@@ -73,5 +73,5 @@ add_task(async function () {
         "as is our requested dominator tree display");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_09.js b/devtools/client/memory/test/unit/test_dominator_trees_09.js
index af1566b43178..1f6ab222baa9 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_09.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_09.js
@@ -22,23 +22,23 @@ const {
   takeSnapshotAndCensus,
 } = require("devtools/client/memory/actions/snapshot");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(changeView(viewState.DOMINATOR_TREE));
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
+  yield waitUntilCensusState(store, s => s.treeMap, [treeMapState.SAVED]);
   ok(!getState().snapshots[0].dominatorTree,
      "There shouldn't be a dominator tree model yet since it is not computed " +
      "until we switch to the dominators view.");
 
   // Wait for the dominator tree to start fetching.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
@@ -59,7 +59,7 @@ add_task(async function () {
     labelDisplays.allocationStack));
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
 
   equal(getState().snapshots[0].dominatorTree.display,
@@ -70,5 +70,5 @@ add_task(async function () {
         "as is our requested dominator tree display");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_dominator_trees_10.js b/devtools/client/memory/test/unit/test_dominator_trees_10.js
index 84496e107cdf..8d2ff9ddbf45 100644
--- a/devtools/client/memory/test/unit/test_dominator_trees_10.js
+++ b/devtools/client/memory/test/unit/test_dominator_trees_10.js
@@ -22,10 +22,10 @@ const {
   setLabelDisplayAndRefresh,
 } = require("devtools/client/memory/actions/label-display");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
@@ -33,7 +33,7 @@ add_task(async function () {
   dispatch(takeSnapshotAndCensus(front, heapWorker));
 
   // Wait for the dominator tree to finish being fetched.
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0] &&
     state.snapshots[0].dominatorTree &&
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
@@ -53,11 +53,11 @@ add_task(async function () {
   equal(getState().labelDisplay, labelDisplays.allocationStack,
         "Using labelDisplays.allocationStack now");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.FETCHING);
   ok(true, "We started re-fetching the dominator tree");
 
-  await waitUntilState(store, state =>
+  yield waitUntilState(store, state =>
     state.snapshots[0].dominatorTree.state === dominatorTreeState.LOADED);
   ok(true, "The dominator tree was loaded again");
 
@@ -67,5 +67,5 @@ add_task(async function () {
         "Focused node is the same as before");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_individuals_01.js b/devtools/client/memory/test/unit/test_individuals_01.js
index 899bb32c4e12..ba06b4cc28e8 100644
--- a/devtools/client/memory/test/unit/test_individuals_01.js
+++ b/devtools/client/memory/test/unit/test_individuals_01.js
@@ -24,10 +24,10 @@ const EXPECTED_INDIVIDUAL_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -36,7 +36,7 @@ add_task(async function () {
 
   dispatch(changeView(viewState.CENSUS));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   const root = getState().snapshots[0].census.report;
   ok(root, "Should have a census");
@@ -55,7 +55,7 @@ add_task(async function () {
 
   // Wait for each expected state.
   for (let state of EXPECTED_INDIVIDUAL_STATES) {
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -69,5 +69,5 @@ add_task(async function () {
      "Should have a positive number of nodes");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_individuals_02.js b/devtools/client/memory/test/unit/test_individuals_02.js
index 4f8d53b7dd54..f3b80c82ac69 100644
--- a/devtools/client/memory/test/unit/test_individuals_02.js
+++ b/devtools/client/memory/test/unit/test_individuals_02.js
@@ -27,10 +27,10 @@ const EXPECTED_INDIVIDUAL_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -39,7 +39,7 @@ add_task(async function () {
 
   dispatch(changeView(viewState.CENSUS));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   const root = getState().snapshots[0].census.report;
   ok(root, "Should have a census");
@@ -67,7 +67,7 @@ add_task(async function () {
 
   // Wait for each expected state.
   for (let state of EXPECTED_INDIVIDUAL_STATES) {
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -81,5 +81,5 @@ add_task(async function () {
      "Should have a positive number of nodes");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_individuals_03.js b/devtools/client/memory/test/unit/test_individuals_03.js
index 41b47b2b1651..12b7ff679b81 100644
--- a/devtools/client/memory/test/unit/test_individuals_03.js
+++ b/devtools/client/memory/test/unit/test_individuals_03.js
@@ -29,10 +29,10 @@ const EXPECTED_INDIVIDUAL_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -42,14 +42,14 @@ add_task(async function () {
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census,
+  yield waitUntilCensusState(store, s => s.census,
                              [censusState.SAVED, censusState.SAVED]);
 
   dispatch(changeView(viewState.DIFFING));
   dispatch(selectSnapshotForDiffingAndRefresh(heapWorker, getState().snapshots[0]));
   dispatch(selectSnapshotForDiffingAndRefresh(heapWorker, getState().snapshots[1]));
 
-  await waitUntilState(store, state => {
+  yield waitUntilState(store, state => {
     return state.diffing &&
            state.diffing.state === diffingState.TOOK_DIFF;
   });
@@ -73,7 +73,7 @@ add_task(async function () {
                             reportLeafIndex));
 
   for (let state of EXPECTED_INDIVIDUAL_STATES) {
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -90,7 +90,7 @@ add_task(async function () {
 
   dispatch(popViewAndRefresh(heapWorker));
 
-  await waitUntilState(store, state => {
+  yield waitUntilState(store, state => {
     return state.diffing &&
       state.diffing.state === diffingState.TOOK_DIFF;
   });
@@ -99,5 +99,5 @@ add_task(async function () {
      "We have our census diff again after popping back to the last view");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_individuals_04.js b/devtools/client/memory/test/unit/test_individuals_04.js
index 284d362421f2..4391508c5a8d 100644
--- a/devtools/client/memory/test/unit/test_individuals_04.js
+++ b/devtools/client/memory/test/unit/test_individuals_04.js
@@ -27,10 +27,10 @@ const EXPECTED_INDIVIDUAL_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -40,7 +40,7 @@ add_task(async function () {
   // Take a snapshot and wait for the census to finish.
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   // Fetch individuals.
 
@@ -60,7 +60,7 @@ add_task(async function () {
                             reportLeafIndex));
 
   for (let state of EXPECTED_INDIVIDUAL_STATES) {
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -82,5 +82,5 @@ add_task(async function () {
   }
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_individuals_05.js b/devtools/client/memory/test/unit/test_individuals_05.js
index 9e4de84aba2d..25ada7eb6d03 100644
--- a/devtools/client/memory/test/unit/test_individuals_05.js
+++ b/devtools/client/memory/test/unit/test_individuals_05.js
@@ -28,10 +28,10 @@ const EXPECTED_INDIVIDUAL_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -41,7 +41,7 @@ add_task(async function () {
   // Take a snapshot and wait for the census to finish.
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   // Fetch individuals.
 
@@ -61,7 +61,7 @@ add_task(async function () {
                             reportLeafIndex));
 
   for (let state of EXPECTED_INDIVIDUAL_STATES) {
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -75,5 +75,5 @@ add_task(async function () {
      "Should have a positive number of nodes");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_individuals_06.js b/devtools/client/memory/test/unit/test_individuals_06.js
index d8feca6b1ed0..9eafd335fb35 100644
--- a/devtools/client/memory/test/unit/test_individuals_06.js
+++ b/devtools/client/memory/test/unit/test_individuals_06.js
@@ -26,10 +26,10 @@ const EXPECTED_INDIVIDUAL_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -38,7 +38,7 @@ add_task(async function () {
   // Take a snapshot and wait for the census to finish.
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   // Fetch individuals.
 
@@ -58,7 +58,7 @@ add_task(async function () {
                             reportLeafIndex));
 
   for (let state of EXPECTED_INDIVIDUAL_STATES) {
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -77,5 +77,5 @@ add_task(async function () {
         "Went back to census view");
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_pop_view_01.js b/devtools/client/memory/test/unit/test_pop_view_01.js
index 5d5eef8c1bf7..520e1608a863 100644
--- a/devtools/client/memory/test/unit/test_pop_view_01.js
+++ b/devtools/client/memory/test/unit/test_pop_view_01.js
@@ -25,10 +25,10 @@ const TEST_STATES = [
   individualsState.FETCHED,
 ];
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   const { getState, dispatch } = store;
 
@@ -37,7 +37,7 @@ add_task(async function () {
 
   dispatch(changeView(viewState.CENSUS));
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   const root = getState().snapshots[0].census.report;
   ok(root, "Should have a census");
@@ -58,7 +58,7 @@ add_task(async function () {
                               reportLeafIndex));
 
     // Wait for the expected test state.
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.INDIVIDUALS &&
              s.individuals &&
              s.individuals.state === state;
@@ -67,12 +67,12 @@ add_task(async function () {
 
     // Pop back to the CENSUS state.
     dispatch(popViewAndRefresh(heapWorker));
-    await waitUntilState(store, s => {
+    yield waitUntilState(store, s => {
       return s.view.state === viewState.CENSUS;
     });
     ok(!getState().individuals, "Should no longer have individuals");
   }
 
   heapWorker.destroy();
-  await front.detach();
+  yield front.detach();
 });
diff --git a/devtools/client/memory/test/unit/test_utils-get-snapshot-totals.js b/devtools/client/memory/test/unit/test_utils-get-snapshot-totals.js
index c42389b4c1a3..d0a113c46f6b 100644
--- a/devtools/client/memory/test/unit/test_utils-get-snapshot-totals.js
+++ b/devtools/client/memory/test/unit/test_utils-get-snapshot-totals.js
@@ -14,20 +14,20 @@ const { takeSnapshotAndCensus } = require("devtools/client/memory/actions/snapsh
 const { setCensusDisplayAndRefresh } = require("devtools/client/memory/actions/census-display");
 const { changeView } = require("devtools/client/memory/actions/view");
 
-add_task(async function () {
+add_task(function* () {
   let front = new StubbedMemoryFront();
   let heapWorker = new HeapAnalysesClient();
-  await front.attach();
+  yield front.attach();
   let store = Store();
   let { getState, dispatch } = store;
 
   dispatch(changeView(viewState.CENSUS));
 
-  await dispatch(setCensusDisplayAndRefresh(heapWorker,
+  yield dispatch(setCensusDisplayAndRefresh(heapWorker,
                                             censusDisplays.allocationStack));
 
   dispatch(takeSnapshotAndCensus(front, heapWorker));
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
 
   ok(!getState().snapshots[0].census.display.inverted, "Snapshot is not inverted");
 
@@ -46,8 +46,8 @@ add_task(async function () {
   dispatch(setCensusDisplayAndRefresh(heapWorker,
                                       censusDisplays.invertedAllocationStack));
 
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVING]);
-  await waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVING]);
+  yield waitUntilCensusState(store, s => s.census, [censusState.SAVED]);
   ok(getState().snapshots[0].census.display.inverted, "Snapshot is inverted");
 
   result = getSnapshotTotals(getState().snapshots[0].census);
diff --git a/devtools/client/netmonitor/test/browser_net_view-source-debugger.js b/devtools/client/netmonitor/test/browser_net_view-source-debugger.js
index ac4e12dc2335..bc98af104b23 100644
--- a/devtools/client/netmonitor/test/browser_net_view-source-debugger.js
+++ b/devtools/client/netmonitor/test/browser_net_view-source-debugger.js
@@ -61,8 +61,7 @@ async function checkClickOnNode(toolbox, frameLinkNode) {
   // wait for the promise to resolve
   await onJsDebuggerSelected;
 
-  let dbg = await toolbox.getPanelWhenReady("jsdebugger");
-  await waitUntil(() => dbg._selectors.getSelectedSource(dbg._getState()));
+  let dbg = toolbox.getPanel("jsdebugger");
   is(
     dbg._selectors.getSelectedSource(dbg._getState()).get("url"),
     url,
diff --git a/devtools/client/performance/components/test/head.js b/devtools/client/performance/components/test/head.js
index 7957e3710129..691d5ddabc7f 100644
--- a/devtools/client/performance/components/test/head.js
+++ b/devtools/client/performance/components/test/head.js
@@ -11,6 +11,7 @@ let { Assert } = require("resource://testing-common/Assert.jsm");
 let { BrowserLoader } = ChromeUtils.import("resource://devtools/client/shared/browser-loader.js", {});
 let defer = require("devtools/shared/defer");
 let flags = require("devtools/shared/flags");
+let { Task } = require("devtools/shared/task");
 let { TargetFactory } = require("devtools/client/framework/target");
 let { Toolbox } = require("devtools/client/framework/toolbox");
 
diff --git a/devtools/client/performance/components/test/test_jit_optimizations_01.html b/devtools/client/performance/components/test/test_jit_optimizations_01.html
index bc09d9845664..8e82bcf89a68 100644
--- a/devtools/client/performance/components/test/test_jit_optimizations_01.html
+++ b/devtools/client/performance/components/test/test_jit_optimizations_01.html
@@ -13,7 +13,7 @@ Test the rendering of the JIT Optimizations tree. Tests when jit data has observ
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -32,7 +32,7 @@ window.onload = async function () {
       optimizationSites: OPTS_DATA_GENERAL,
       autoExpandDepth: 1000,
     }), window.document.body);
-    await forceRender(opts);
+    yield forceRender(opts);
 
     checkOptimizationHeader("myfunc", "file.js", "1");
 
@@ -63,7 +63,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/performance/modules/widgets/graphs.js b/devtools/client/performance/modules/widgets/graphs.js
index 6af864ca2ee2..ff4ba5524369 100644
--- a/devtools/client/performance/modules/widgets/graphs.js
+++ b/devtools/client/performance/modules/widgets/graphs.js
@@ -7,6 +7,7 @@
  * This file contains the base line graph that all Performance line graphs use.
  */
 
+const { Task } = require("devtools/shared/task");
 const { extend } = require("devtools/shared/extend");
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 const MountainGraphWidget = require("devtools/client/shared/widgets/MountainGraphWidget");
@@ -205,12 +206,12 @@ GraphsController.prototype = {
    * Saves rendering progress as a promise to be consumed by `destroy`,
    * to wait for cleaning up rendering during destruction.
    */
-  async render(recordingData, resolution) {
+  render: Task.async(function* (recordingData, resolution) {
     // Get the previous render promise so we don't start rendering
     // until the previous render cycle completes, which can occur
     // especially when a recording is finished, and triggers a
     // fresh rendering at a higher rate
-    await (this._rendering && this._rendering.promise);
+    yield (this._rendering && this._rendering.promise);
 
     // Check after yielding to ensure we're not tearing down,
     // as this can create a race condition in tests
@@ -219,17 +220,17 @@ GraphsController.prototype = {
     }
 
     this._rendering = defer();
-    for (let graph of (await this._getEnabled())) {
-      await graph.setPerformanceData(recordingData, resolution);
+    for (let graph of (yield this._getEnabled())) {
+      yield graph.setPerformanceData(recordingData, resolution);
       this.emit("rendered", graph.graphName);
     }
     this._rendering.resolve();
-  },
+  }),
 
   /**
    * Destroys the underlying graphs.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     let primary = this._getPrimaryLink();
 
     this._destroyed = true;
@@ -241,13 +242,13 @@ GraphsController.prototype = {
     // If there was rendering, wait until the most recent render cycle
     // has finished
     if (this._rendering) {
-      await this._rendering.promise;
+      yield this._rendering.promise;
     }
 
     for (let graph of this.getWidgets()) {
-      await graph.destroy();
+      yield graph.destroy();
     }
-  },
+  }),
 
   /**
    * Applies the theme to the underlying graphs. Optionally takes
@@ -266,7 +267,7 @@ GraphsController.prototype = {
    * to the graph if it is enabled once it's ready, or otherwise returns
    * null if disabled.
    */
-  async isAvailable(graphName) {
+  isAvailable: Task.async(function* (graphName) {
     if (!this._enabled.has(graphName)) {
       return null;
     }
@@ -274,12 +275,12 @@ GraphsController.prototype = {
     let graph = this.get(graphName);
 
     if (!graph) {
-      graph = await this._construct(graphName);
+      graph = yield this._construct(graphName);
     }
 
-    await graph.ready();
+    yield graph.ready();
     return graph;
-  },
+  }),
 
   /**
    * Enable or disable a subgraph controlled by GraphsController.
@@ -355,23 +356,23 @@ GraphsController.prototype = {
   /**
    * Makes sure the selection is enabled or disabled in all the graphs.
    */
-  async selectionEnabled(enabled) {
-    for (let graph of (await this._getEnabled())) {
+  selectionEnabled: Task.async(function* (enabled) {
+    for (let graph of (yield this._getEnabled())) {
       graph.selectionEnabled = enabled;
     }
-  },
+  }),
 
   /**
    * Creates the graph `graphName` and initializes it.
    */
-  async _construct(graphName) {
+  _construct: Task.async(function* (graphName) {
     let def = this._definition[graphName];
     let el = this.$(def.selector);
     let filter = this._getFilter();
     let graph = this._graphs[graphName] = new def.constructor(el, filter);
     graph.graphName = graphName;
 
-    await graph.ready();
+    yield graph.ready();
 
     // Sync the graphs' animations and selections together
     if (def.primaryLink) {
@@ -386,7 +387,7 @@ GraphsController.prototype = {
 
     this.setTheme();
     return graph;
-  },
+  }),
 
   /**
    * Returns the main graph for this collection, that all graphs
@@ -409,20 +410,20 @@ GraphsController.prototype = {
    * as those could be enabled. Uses caching, as rendering happens many times per second,
    * compared to how often which graphs/features are changed (rarely).
    */
-  async _getEnabled() {
+  _getEnabled: Task.async(function* () {
     if (this._enabledGraphs) {
       return this._enabledGraphs;
     }
     let enabled = [];
     for (let graphName of this._enabled) {
-      let graph = await this.isAvailable(graphName);
+      let graph = yield this.isAvailable(graphName);
       if (graph) {
         enabled.push(graph);
       }
     }
     this._enabledGraphs = enabled;
     return this._enabledGraphs;
-  },
+  }),
 };
 
 /**
@@ -440,10 +441,10 @@ function OptimizationsGraph(parent) {
 
 OptimizationsGraph.prototype = extend(MountainGraphWidget.prototype, {
 
-  async render(threadNode, frameNode) {
+  render: Task.async(function* (threadNode, frameNode) {
     // Regardless if we draw or clear the graph, wait
     // until it's ready.
-    await this.ready();
+    yield this.ready();
 
     if (!threadNode || !frameNode) {
       this.setData([]);
@@ -476,8 +477,8 @@ OptimizationsGraph.prototype = extend(MountainGraphWidget.prototype, {
     }
 
     this.dataOffsetX = startTime;
-    await this.setData(data);
-  },
+    yield this.setData(data);
+  }),
 
   /**
    * Sets the theme via `theme` to either "light" or "dark",
diff --git a/devtools/client/performance/panel.js b/devtools/client/performance/panel.js
index df3748da309f..bd6a31e23420 100644
--- a/devtools/client/performance/panel.js
+++ b/devtools/client/performance/panel.js
@@ -5,6 +5,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 
+const { Task } = require("devtools/shared/task");
 const defer = require("devtools/shared/defer");
 
 loader.lazyRequireGetter(this, "EventEmitter",
@@ -27,7 +28,7 @@ PerformancePanel.prototype = {
    *         A promise that is resolved when the Performance tool
    *         completes opening.
    */
-  async open() {
+  open: Task.async(function* () {
     if (this._opening) {
       return this._opening;
     }
@@ -42,7 +43,7 @@ PerformancePanel.prototype = {
     // the same front, and the toolbox will also initialize the front,
     // but redo it here so we can hook into the same event to prevent race conditions
     // in the case of the front still being in the process of opening.
-    let front = await this.panelWin.gToolbox.initPerformance();
+    let front = yield this.panelWin.gToolbox.initPerformance();
 
     // This should only happen if this is completely unsupported (when profiler
     // does not exist), and in that case, the tool shouldn't be available,
@@ -55,7 +56,7 @@ PerformancePanel.prototype = {
     let { PerformanceController, EVENTS } = this.panelWin;
     PerformanceController.on(EVENTS.RECORDING_ADDED, this._checkRecordingStatus);
     PerformanceController.on(EVENTS.RECORDING_STATE_CHANGE, this._checkRecordingStatus);
-    await this.panelWin.startupPerformance();
+    yield this.panelWin.startupPerformance();
 
     // Fire this once incase we have an in-progress recording (console profile)
     // that caused this start up, and no state change yet, so we can highlight the
@@ -67,7 +68,7 @@ PerformancePanel.prototype = {
 
     deferred.resolve(this);
     return this._opening;
-  },
+  }),
 
   // DevToolPanel API
 
@@ -75,7 +76,7 @@ PerformancePanel.prototype = {
     return this.toolbox.target;
   },
 
-  async destroy() {
+  destroy: Task.async(function* () {
     // Make sure this panel is not already destroyed.
     if (this._destroyed) {
       return;
@@ -84,10 +85,10 @@ PerformancePanel.prototype = {
     let { PerformanceController, EVENTS } = this.panelWin;
     PerformanceController.off(EVENTS.RECORDING_ADDED, this._checkRecordingStatus);
     PerformanceController.off(EVENTS.RECORDING_STATE_CHANGE, this._checkRecordingStatus);
-    await this.panelWin.shutdownPerformance();
+    yield this.panelWin.shutdownPerformance();
     this.emit("destroyed");
     this._destroyed = true;
-  },
+  }),
 
   _checkRecordingStatus: function () {
     if (this.panelWin.PerformanceController.isRecording()) {
diff --git a/devtools/client/performance/performance-controller.js b/devtools/client/performance/performance-controller.js
index e71470d7e450..c300a62971c7 100644
--- a/devtools/client/performance/performance-controller.js
+++ b/devtools/client/performance/performance-controller.js
@@ -12,6 +12,7 @@ var { loader, require } = BrowserLoaderModule.BrowserLoader({
   baseURI: "resource://devtools/client/performance/",
   window
 });
+var { Task } = require("devtools/shared/task");
 /* exported ViewHelpers, WidgetMethods, setNamedTimeout, clearNamedTimeout */
 var { ViewHelpers, WidgetMethods, setNamedTimeout, clearNamedTimeout } = require("devtools/client/shared/widgets/view-helpers");
 var { PrefObserver } = require("devtools/client/shared/prefs");
@@ -90,20 +91,20 @@ var gToolbox, gTarget, gFront;
 /**
  * Initializes the profiler controller and views.
  */
-var startupPerformance = async function () {
-  await PerformanceController.initialize();
-  await PerformanceView.initialize();
+var startupPerformance = Task.async(function* () {
+  yield PerformanceController.initialize();
+  yield PerformanceView.initialize();
   PerformanceController.enableFrontEventListeners();
-};
+});
 
 /**
  * Destroys the profiler controller and views.
  */
-var shutdownPerformance = async function () {
-  await PerformanceController.destroy();
-  await PerformanceView.destroy();
+var shutdownPerformance = Task.async(function* () {
+  yield PerformanceController.destroy();
+  yield PerformanceView.destroy();
   PerformanceController.disableFrontEventListeners();
-};
+});
 
 /**
  * Functions handling target-related lifetime events and
@@ -117,7 +118,7 @@ var PerformanceController = {
    * Listen for events emitted by the current tab target and
    * main UI events.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     this._telemetry = new PerformanceTelemetry(this);
     this.startRecording = this.startRecording.bind(this);
     this.stopRecording = this.stopRecording.bind(this);
@@ -149,7 +150,7 @@ var PerformanceController = {
 
     this._prefObserver = new PrefObserver("devtools.");
     this._prefObserver.on("devtools.theme", this._onThemeChanged);
-  },
+  }),
 
   /**
    * Remove events handled by the PerformanceController
@@ -238,22 +239,22 @@ var PerformanceController = {
    * Checks whether or not a new recording is supported by the PerformanceFront.
    * @return Promise:boolean
    */
-  async canCurrentlyRecord() {
-    let hasActor = await gTarget.hasActor("performance");
+  canCurrentlyRecord: Task.async(function* () {
+    let hasActor = yield gTarget.hasActor("performance");
     if (!hasActor) {
       return true;
     }
-    let actorCanCheck = await gTarget.actorHasMethod("performance", "canCurrentlyRecord");
+    let actorCanCheck = yield gTarget.actorHasMethod("performance", "canCurrentlyRecord");
     if (!actorCanCheck) {
       return true;
     }
-    return (await gFront.canCurrentlyRecord()).success;
-  },
+    return (yield gFront.canCurrentlyRecord()).success;
+  }),
 
   /**
    * Starts recording with the PerformanceFront.
    */
-  async startRecording() {
+  startRecording: Task.async(function* () {
     let options = {
       withMarkers: true,
       withTicks: this.getOption("enable-framerate"),
@@ -267,7 +268,7 @@ var PerformanceController = {
       sampleFrequency: this.getPref("profiler-sample-frequency")
     };
 
-    let recordingStarted = await gFront.startRecording(options);
+    let recordingStarted = yield gFront.startRecording(options);
 
     // In some cases, like when the target has a private browsing tab,
     // recording is not currently supported because of the profiler module.
@@ -278,16 +279,16 @@ var PerformanceController = {
     } else {
       this.emit(EVENTS.BACKEND_READY_AFTER_RECORDING_START);
     }
-  },
+  }),
 
   /**
    * Stops recording with the PerformanceFront.
    */
-  async stopRecording() {
+  stopRecording: Task.async(function* () {
     let recording = this.getLatestManualRecording();
-    await gFront.stopRecording(recording);
+    yield gFront.stopRecording(recording);
     this.emit(EVENTS.BACKEND_READY_AFTER_RECORDING_STOP);
-  },
+  }),
 
   /**
    * Saves the given recording to a file. Emits `EVENTS.RECORDING_EXPORTED`
@@ -298,26 +299,26 @@ var PerformanceController = {
    * @param nsIFile file
    *        The file to stream the data into.
    */
-  async exportRecording(_, recording, file) {
-    await recording.exportRecording(file);
+  exportRecording: Task.async(function* (_, recording, file) {
+    yield recording.exportRecording(file);
     this.emit(EVENTS.RECORDING_EXPORTED, recording, file);
-  },
+  }),
 
    /**
    * Clears all completed recordings from the list as well as the current non-console
    * recording. Emits `EVENTS.RECORDING_DELETED` when complete so other components can
    * clean up.
    */
-  async clearRecordings() {
+  clearRecordings: Task.async(function* () {
     for (let i = this._recordings.length - 1; i >= 0; i--) {
       let model = this._recordings[i];
       if (!model.isConsole() && model.isRecording()) {
-        await this.stopRecording();
+        yield this.stopRecording();
       }
       // If last recording is not recording, but finalizing itself,
       // wait for that to finish
       if (!model.isRecording() && !model.isCompleted()) {
-        await this.waitForStateChangeOnRecording(model, "recording-stopped");
+        yield this.waitForStateChangeOnRecording(model, "recording-stopped");
       }
       // If recording is completed,
       // clean it up from UI and remove it from the _recordings array.
@@ -333,7 +334,7 @@ var PerformanceController = {
     } else {
       this.setCurrentRecording(null);
     }
-  },
+  }),
 
   /**
    * Loads a recording from a file, adding it to the recordings list. Emits
@@ -342,12 +343,12 @@ var PerformanceController = {
    * @param nsIFile file
    *        The file to import the data from.
    */
-  async importRecording(_, file) {
-    let recording = await gFront.importRecording(file);
+  importRecording: Task.async(function* (_, file) {
+    let recording = yield gFront.importRecording(file);
     this._addRecordingIfUnknown(recording);
 
     this.emit(EVENTS.RECORDING_IMPORTED, recording);
-  },
+  }),
 
   /**
    * Sets the currently active PerformanceRecording. Should rarely be called directly,
@@ -537,7 +538,7 @@ var PerformanceController = {
    * @param {string} expectedState
    * @return {Promise}
    */
-  async waitForStateChangeOnRecording(recording, expectedState) {
+  waitForStateChangeOnRecording: Task.async(function* (recording, expectedState) {
     let deferred = defer();
     this.on(EVENTS.RECORDING_STATE_CHANGE, function handler(state, model) {
       if (state === expectedState && model === recording) {
@@ -545,8 +546,8 @@ var PerformanceController = {
         deferred.resolve();
       }
     });
-    await deferred.promise;
-  },
+    yield deferred.promise;
+  }),
 
   /**
    * Called on init, sets an `e10s` attribute on the main view container with
diff --git a/devtools/client/performance/performance-view.js b/devtools/client/performance/performance-view.js
index a6f2dbd91df4..526f3a8ec27e 100644
--- a/devtools/client/performance/performance-view.js
+++ b/devtools/client/performance/performance-view.js
@@ -115,7 +115,7 @@ var PerformanceView = {
   /**
    * Sets up the view with event binding and main subviews.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     this._onRecordButtonClick = this._onRecordButtonClick.bind(this);
     this._onImportButtonClick = this._onImportButtonClick.bind(this);
     this._onClearButtonClick = this._onClearButtonClick.bind(this);
@@ -133,7 +133,7 @@ var PerformanceView = {
     PerformanceController.on(EVENTS.BACKEND_FAILED_AFTER_RECORDING_START,
                              this._onNewRecordingFailed);
 
-    if (await PerformanceController.canCurrentlyRecord()) {
+    if (yield PerformanceController.canCurrentlyRecord()) {
       this.setState("empty");
     } else {
       this.setState("unavailable");
@@ -141,10 +141,10 @@ var PerformanceView = {
 
     // Initialize the ToolbarView first, because other views may need access
     // to the OptionsView via the controller, to read prefs.
-    await ToolbarView.initialize();
-    await RecordingsView.initialize();
-    await OverviewView.initialize();
-    await DetailsView.initialize();
+    yield ToolbarView.initialize();
+    yield RecordingsView.initialize();
+    yield OverviewView.initialize();
+    yield DetailsView.initialize();
 
     // DE-XUL: Begin migrating the toolbar to React. Temporarily hold state here.
     this._recordingControlsState = {
@@ -161,7 +161,7 @@ var PerformanceView = {
                                         .map(createHtmlMount);
 
     this._renderRecordingControls();
-  },
+  }),
 
   /**
    * DE-XUL: Render the recording controls and buttons using React.
@@ -177,7 +177,7 @@ var PerformanceView = {
   /**
    * Unbinds events and destroys subviews.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     PerformanceController.off(EVENTS.RECORDING_SELECTED, this._onRecordingSelected);
     PerformanceController.off(EVENTS.RECORDING_PROFILER_STATUS_UPDATE,
                               this._onProfilerStatusUpdated);
@@ -187,11 +187,11 @@ var PerformanceView = {
     PerformanceController.off(EVENTS.BACKEND_FAILED_AFTER_RECORDING_START,
                               this._onNewRecordingFailed);
 
-    await ToolbarView.destroy();
-    await RecordingsView.destroy();
-    await OverviewView.destroy();
-    await DetailsView.destroy();
-  },
+    yield ToolbarView.destroy();
+    yield RecordingsView.destroy();
+    yield OverviewView.destroy();
+    yield DetailsView.destroy();
+  }),
 
   /**
    * Sets the state of the profiler view. Possible options are "unavailable",
diff --git a/devtools/client/performance/test/browser_aaa-run-first-leaktest.js b/devtools/client/performance/test/browser_aaa-run-first-leaktest.js
index d06087ab403e..d3ecef42e328 100644
--- a/devtools/client/performance/test/browser_aaa-run-first-leaktest.js
+++ b/devtools/client/performance/test/browser_aaa-run-first-leaktest.js
@@ -10,8 +10,8 @@
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 
-add_task(async function () {
-  let { target, toolbox, panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { target, toolbox, panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,5 +24,5 @@ add_task(async function () {
   ok(panel.panelWin.gToolbox, "Should have a toolbox reference on the panel window.");
   ok(panel.panelWin.gFront, "Should have a front reference on the panel window.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-button-states.js b/devtools/client/performance/test/browser_perf-button-states.js
index 4ed11ea0f9fa..7f7ca1b2a463 100644
--- a/devtools/client/performance/test/browser_perf-button-states.js
+++ b/devtools/client/performance/test/browser_perf-button-states.js
@@ -10,8 +10,8 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -33,16 +33,16 @@ add_task(async function () {
   });
 
   click(recordButton);
-  await uiStartClick;
+  yield uiStartClick;
 
   checkRecordButtonsStates(true, true);
 
-  await recordingStarted;
+  yield recordingStarted;
 
   checkRecordButtonsStates(true, false);
 
-  await backendStartReady;
-  await uiStateRecording;
+  yield backendStartReady;
+  yield uiStateRecording;
 
   let uiStopClick = once(PerformanceView, EVENTS.UI_STOP_RECORDING);
   let recordingStopped = once(PerformanceController, EVENTS.RECORDING_STATE_CHANGE, {
@@ -55,15 +55,15 @@ add_task(async function () {
   });
 
   click(recordButton);
-  await uiStopClick;
-  await recordingStopped;
+  yield uiStopClick;
+  yield recordingStopped;
 
   checkRecordButtonsStates(false, false);
 
-  await backendStopReady;
-  await uiStateRecorded;
+  yield backendStopReady;
+  yield uiStateRecorded;
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 
   function checkRecordButtonsStates(checked, locked) {
     for (let button of $$(".record-button")) {
diff --git a/devtools/client/performance/test/browser_perf-calltree-js-categories.js b/devtools/client/performance/test/browser_perf-calltree-js-categories.js
index 726e412399c2..c0710932f7fe 100644
--- a/devtools/client/performance/test/browser_perf-calltree-js-categories.js
+++ b/devtools/client/performance/test/browser_perf-calltree-js-categories.js
@@ -14,8 +14,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { busyWait } = require("devtools/client/performance/test/helpers/wait-utils");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -25,14 +25,14 @@ add_task(async function () {
   // Enable platform data to show the categories in the tree.
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, true);
 
-  await startRecording(panel);
+  yield startRecording(panel);
   // To show the `Gecko` category in the tree.
-  await busyWait(100);
-  await stopRecording(panel);
+  yield busyWait(100);
+  yield stopRecording(panel);
 
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
 
   is($(".call-tree-cells-container").hasAttribute("categories-hidden"), false,
     "The call tree cells container should show the categories now.");
@@ -47,7 +47,7 @@ add_task(async function () {
   ok(!geckoCategoryPresent($$),
     "A category node with the text `Gecko` doesn't exist in the tree anymore.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
 
 function geckoCategoryPresent($$) {
diff --git a/devtools/client/performance/test/browser_perf-calltree-js-columns.js b/devtools/client/performance/test/browser_perf-calltree-js-columns.js
index b54fc1689f5d..5c8b6e2f36c4 100644
--- a/devtools/client/performance/test/browser_perf-calltree-js-columns.js
+++ b/devtools/client/performance/test/browser_perf-calltree-js-columns.js
@@ -13,8 +13,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { busyWait } = require("devtools/client/performance/test/helpers/wait-utils");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,14 +24,14 @@ add_task(async function () {
   // Enable platform data to show the platform functions in the tree.
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, true);
 
-  await startRecording(panel);
+  yield startRecording(panel);
   // To show the `busyWait` function in the tree.
-  await busyWait(100);
-  await stopRecording(panel);
+  yield busyWait(100);
+  yield stopRecording(panel);
 
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
 
   ok(DetailsView.isViewSelected(JsCallTreeView), "The call tree is now selected.");
 
@@ -46,7 +46,7 @@ add_task(async function () {
     "function": true
   });
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
 
 function testCells($, $$, visibleCells) {
diff --git a/devtools/client/performance/test/browser_perf-calltree-js-events.js b/devtools/client/performance/test/browser_perf-calltree-js-events.js
index e0198a95a2e0..c93c7f069633 100644
--- a/devtools/client/performance/test/browser_perf-calltree-js-events.js
+++ b/devtools/client/performance/test/browser_perf-calltree-js-events.js
@@ -13,20 +13,20 @@ const { synthesizeProfile } = require("devtools/client/performance/test/helpers/
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { ThreadNode } = require("devtools/client/performance/modules/logic/tree-model");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, $, DetailsView, OverviewView, JsCallTreeView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
 
   // Mock the profile used so we can get a deterministic tree created.
   let profile = synthesizeProfile();
@@ -54,5 +54,5 @@ add_task(async function () {
   JsCallTreeView.off("focus", onFocus);
   is(count, 4, "Several focus events are fired for the calltree.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-calltree-memory-columns.js b/devtools/client/performance/test/browser_perf-calltree-memory-columns.js
index 2a0557fcf2e0..9eb8a8de9cba 100644
--- a/devtools/client/performance/test/browser_perf-calltree-memory-columns.js
+++ b/devtools/client/performance/test/browser_perf-calltree-memory-columns.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -23,12 +23,12 @@ add_task(async function () {
   // Enable allocations to test.
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
-  await DetailsView.selectView("memory-calltree");
-  await rendered;
+  yield DetailsView.selectView("memory-calltree");
+  yield rendered;
 
   ok(DetailsView.isViewSelected(MemoryCallTreeView), "The call tree is now selected.");
 
@@ -49,7 +49,7 @@ add_task(async function () {
     "function": true
   });
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
 
 function testCells($, $$, visibleCells) {
diff --git a/devtools/client/performance/test/browser_perf-console-record-01.js b/devtools/client/performance/test/browser_perf-console-record-01.js
index b3792986e0e9..9353c2f9a478 100644
--- a/devtools/client/performance/test/browser_perf-console-record-01.js
+++ b/devtools/client/performance/test/browser_perf-console-record-01.js
@@ -12,20 +12,20 @@ const { initPerformanceInTab, initConsoleInNewTab, teardownToolboxAndRemoveTab }
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  await console.profile("rust");
-  await console.profileEnd("rust");
+  yield console.profile("rust");
+  yield console.profileEnd("rust");
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { PerformanceController, WaterfallView } = panel.panelWin;
 
-  await waitUntil(() => PerformanceController.getRecordings().length == 1);
-  await waitUntil(() => WaterfallView.wasRenderedAtLeastOnce);
+  yield waitUntil(() => PerformanceController.getRecordings().length == 1);
+  yield waitUntil(() => WaterfallView.wasRenderedAtLeastOnce);
 
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 1, "One recording found in the performance panel.");
@@ -39,5 +39,5 @@ add_task(async function () {
   is(selected.getLabel(), "rust",
     "The profile label for the first recording is correct.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-02.js b/devtools/client/performance/test/browser_perf-console-record-02.js
index e150d21cb107..36d0a54d10fd 100644
--- a/devtools/client/performance/test/browser_perf-console-record-02.js
+++ b/devtools/client/performance/test/browser_perf-console-record-02.js
@@ -15,19 +15,19 @@ const { waitUntil } = require("devtools/client/performance/test/helpers/wait-uti
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  await console.profile("rust");
-  await console.profile("rust2");
+  yield console.profile("rust");
+  yield console.profile("rust2");
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { EVENTS, PerformanceController, OverviewView } = panel.panelWin;
 
-  await waitUntil(() => PerformanceController.getRecordings().length == 2);
+  yield waitUntil(() => PerformanceController.getRecordings().length == 2);
 
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 2, "Two recordings found in the performance panel.");
@@ -45,7 +45,7 @@ add_task(async function () {
     "The profile label for the first recording is correct.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -53,8 +53,8 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profileEnd("rust");
-  await stopped;
+  yield console.profileEnd("rust");
+  yield stopped;
 
   stopped = waitForRecordingStoppedEvents(panel, {
     // only emitted for manual recordings
@@ -63,8 +63,8 @@ add_task(async function () {
     skipWaitingForOverview: true,
     skipWaitingForSubview: true,
   });
-  await console.profileEnd("rust2");
-  await stopped;
+  yield console.profileEnd("rust2");
+  yield stopped;
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-03.js b/devtools/client/performance/test/browser_perf-console-record-03.js
index 69fcab6eecdf..a12aab5f2b61 100644
--- a/devtools/client/performance/test/browser_perf-console-record-03.js
+++ b/devtools/client/performance/test/browser_perf-console-record-03.js
@@ -13,21 +13,21 @@ const { waitForRecordingStoppedEvents } = require("devtools/client/performance/t
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  await console.profile("rust");
-  await console.profileEnd("rust");
-  await console.profile("rust2");
+  yield console.profile("rust");
+  yield console.profileEnd("rust");
+  yield console.profile("rust2");
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { PerformanceController, WaterfallView } = panel.panelWin;
 
-  await waitUntil(() => PerformanceController.getRecordings().length == 2);
-  await waitUntil(() => WaterfallView.wasRenderedAtLeastOnce);
+  yield waitUntil(() => PerformanceController.getRecordings().length == 2);
+  yield waitUntil(() => WaterfallView.wasRenderedAtLeastOnce);
 
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 2, "Two recordings found in the performance panel.");
@@ -51,8 +51,8 @@ add_task(async function () {
     skipWaitingForOverview: true,
     skipWaitingForSubview: true,
   });
-  await console.profileEnd("rust2");
-  await stopped;
+  yield console.profileEnd("rust2");
+  yield stopped;
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-04.js b/devtools/client/performance/test/browser_perf-console-record-04.js
index 45ddc5916698..6465bc7460da 100644
--- a/devtools/client/performance/test/browser_perf-console-record-04.js
+++ b/devtools/client/performance/test/browser_perf-console-record-04.js
@@ -14,21 +14,21 @@ const { waitForRecordingStartedEvents, waitForRecordingStoppedEvents } = require
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { EVENTS, PerformanceController, OverviewView } = panel.panelWin;
 
   let started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profile("rust");
-  await started;
+  yield console.profile("rust");
+  yield started;
 
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 1, "One recording found in the performance panel.");
@@ -43,7 +43,7 @@ add_task(async function () {
     "The profile label for the first recording is correct.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -51,8 +51,8 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profileEnd("rust");
-  await stopped;
+  yield console.profileEnd("rust");
+  yield stopped;
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-05.js b/devtools/client/performance/test/browser_perf-console-record-05.js
index 6a32b9b85bac..373fd5b0f40f 100644
--- a/devtools/client/performance/test/browser_perf-console-record-05.js
+++ b/devtools/client/performance/test/browser_perf-console-record-05.js
@@ -14,21 +14,21 @@ const { waitForRecordingStartedEvents, waitForRecordingStoppedEvents } = require
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { EVENTS, PerformanceController, OverviewView } = panel.panelWin;
 
   let started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profile("rust");
-  await started;
+  yield console.profile("rust");
+  yield started;
 
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 1, "One recording found in the performance panel.");
@@ -43,7 +43,7 @@ add_task(async function () {
     "The profile label for the first recording is correct.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -51,8 +51,8 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profileEnd("rust");
-  await stopped;
+  yield console.profileEnd("rust");
+  yield stopped;
 
   started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
@@ -63,8 +63,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile("rust");
-  await started;
+  yield console.profile("rust");
+  yield started;
 
   recordings = PerformanceController.getRecordings();
   is(recordings.length, 2, "Two recordings found in the performance panel.");
@@ -85,8 +85,8 @@ add_task(async function () {
     skipWaitingForOverview: true,
     skipWaitingForSubview: true,
   });
-  await console.profileEnd("rust");
-  await stopped;
+  yield console.profileEnd("rust");
+  yield stopped;
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-06.js b/devtools/client/performance/test/browser_perf-console-record-06.js
index 6b74ea8269b4..f1057c261f2f 100644
--- a/devtools/client/performance/test/browser_perf-console-record-06.js
+++ b/devtools/client/performance/test/browser_perf-console-record-06.js
@@ -13,21 +13,21 @@ const { waitForRecordingStartedEvents, waitForRecordingStoppedEvents } = require
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { EVENTS, PerformanceController, OverviewView } = panel.panelWin;
 
   let started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profile("rust");
-  await started;
+  yield console.profile("rust");
+  yield started;
 
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 1, "A recording found in the performance panel.");
@@ -35,7 +35,7 @@ add_task(async function () {
     "The first console recording should be selected.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -48,8 +48,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile("golang");
-  await started;
+  yield console.profile("golang");
+  yield started;
 
   recordings = PerformanceController.getRecordings();
   is(recordings.length, 2, "Two recordings found in the performance panel.");
@@ -57,7 +57,7 @@ add_task(async function () {
     "The first console recording should still be selected.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -65,8 +65,8 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profileEnd("rust");
-  await stopped;
+  yield console.profileEnd("rust");
+  yield stopped;
 
   recordings = PerformanceController.getRecordings();
   is(recordings.length, 2, "Two recordings found in the performance panel.");
@@ -82,8 +82,8 @@ add_task(async function () {
     skipWaitingForOverview: true,
     skipWaitingForSubview: true,
   });
-  await console.profileEnd("golang");
-  await stopped;
+  yield console.profileEnd("golang");
+  yield stopped;
 
   recordings = PerformanceController.getRecordings();
   is(recordings.length, 2, "Two recordings found in the performance panel.");
@@ -92,5 +92,5 @@ add_task(async function () {
   is(recordings[1].isRecording(), false,
     "The second console recording should no longer be recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-07.js b/devtools/client/performance/test/browser_perf-console-record-07.js
index 7f6afd5fc802..af8dc5144a40 100644
--- a/devtools/client/performance/test/browser_perf-console-record-07.js
+++ b/devtools/client/performance/test/browser_perf-console-record-07.js
@@ -14,21 +14,21 @@ const { waitForRecordingStartedEvents, waitForRecordingStoppedEvents } = require
 const { idleWait } = require("devtools/client/performance/test/helpers/wait-utils");
 const { getSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { PerformanceController } = panel.panelWin;
 
   let started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profile();
-  await started;
+  yield console.profile();
+  yield started;
 
   started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
@@ -39,8 +39,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile("1");
-  await started;
+  yield console.profile("1");
+  yield started;
 
   started = waitForRecordingStartedEvents(panel, {
     // only emitted for manual recordings
@@ -51,8 +51,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile("2");
-  await started;
+  yield console.profile("2");
+  yield started;
 
   let recordings = PerformanceController.getRecordings();
   let selected = getSelectedRecording(panel);
@@ -80,8 +80,8 @@ add_task(async function () {
     // finished recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profileEnd();
-  await stopped;
+  yield console.profileEnd();
+  yield stopped;
 
   selected = getSelectedRecording(panel);
   recordings = PerformanceController.getRecordings();
@@ -98,7 +98,7 @@ add_task(async function () {
 
   info("Trying to `profileEnd` a non-existent console recording.");
   console.profileEnd("fxos");
-  await idleWait(1000);
+  yield idleWait(1000);
 
   selected = getSelectedRecording(panel);
   recordings = PerformanceController.getRecordings();
@@ -123,8 +123,8 @@ add_task(async function () {
     // finished recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profileEnd();
-  await stopped;
+  yield console.profileEnd();
+  yield stopped;
 
   selected = getSelectedRecording(panel);
   recordings = PerformanceController.getRecordings();
@@ -143,8 +143,8 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profileEnd();
-  await stopped;
+  yield console.profileEnd();
+  yield stopped;
 
   selected = getSelectedRecording(panel);
   recordings = PerformanceController.getRecordings();
@@ -161,10 +161,10 @@ add_task(async function () {
 
   info("Trying to `profileEnd` with no pending recordings.");
   console.profileEnd();
-  await idleWait(1000);
+  yield idleWait(1000);
 
   ok(true, "Calling console.profileEnd() with no argument and no pending recordings " +
     "does not throw.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-console-record-08.js b/devtools/client/performance/test/browser_perf-console-record-08.js
index 45f6538c720a..2ad81c413137 100644
--- a/devtools/client/performance/test/browser_perf-console-record-08.js
+++ b/devtools/client/performance/test/browser_perf-console-record-08.js
@@ -39,16 +39,16 @@ function hasBitFlag(expected, actual) {
   return !!(expected & actual);
 }
 
-add_task(async function () {
+add_task(function* () {
   // This test seems to take a very long time to finish on Linux VMs.
   requestLongerTimeout(4);
 
-  let { target, console } = await initConsoleInNewTab({
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { EVENTS, PerformanceController, OverviewView } = panel.panelWin;
 
   info("Recording 1 - Starting console.profile()...");
@@ -56,14 +56,14 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profile("rust");
-  await started;
+  yield console.profile("rust");
+  yield started;
   testRecordings(PerformanceController, [
     CONSOLE + SELECTED + RECORDING
   ]);
 
   info("Recording 2 - Starting manual recording...");
-  await startRecording(panel);
+  yield startRecording(panel);
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL + RECORDING + SELECTED
@@ -79,8 +79,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile("3");
-  await started;
+  yield console.profile("3");
+  yield started;
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL + RECORDING + SELECTED,
@@ -97,8 +97,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile("4");
-  await started;
+  yield console.profile("4");
+  yield started;
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL + RECORDING + SELECTED,
@@ -117,8 +117,8 @@ add_task(async function () {
     // finished recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profileEnd();
-  await stopped;
+  yield console.profileEnd();
+  yield stopped;
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL + RECORDING + SELECTED,
@@ -129,7 +129,7 @@ add_task(async function () {
   info("Recording 4 - Select last recording...");
   let recordingSelected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 3);
-  await recordingSelected;
+  yield recordingSelected;
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL + RECORDING,
@@ -141,7 +141,7 @@ add_task(async function () {
 
   info("Recording 2 - Stop manual recording.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL + SELECTED,
@@ -154,7 +154,7 @@ add_task(async function () {
   info("Recording 1 - Select first recording.");
   recordingSelected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await recordingSelected;
+  yield recordingSelected;
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING + SELECTED,
     MANUAL,
@@ -165,7 +165,7 @@ add_task(async function () {
     "Should be rendering overview a recording in progress is selected.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -180,8 +180,8 @@ add_task(async function () {
     // finished recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profileEnd();
-  await stopped;
+  yield console.profileEnd();
+  yield stopped;
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING + SELECTED,
     MANUAL,
@@ -192,12 +192,12 @@ add_task(async function () {
     "Should be rendering overview a recording in progress is selected.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
   info("Recording 5 - Start one more manual recording.");
-  await startRecording(panel);
+  yield startRecording(panel);
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL,
@@ -209,12 +209,12 @@ add_task(async function () {
     "Should be rendering overview a recording in progress is selected.");
 
   // Ensure overview is still rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
   info("Recording 5 - Stop manual recording.");
-  await stopRecording(panel);
+  yield stopRecording(panel);
   testRecordings(PerformanceController, [
     CONSOLE + RECORDING,
     MANUAL,
@@ -236,8 +236,8 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profileEnd();
-  await stopped;
+  yield console.profileEnd();
+  yield stopped;
   testRecordings(PerformanceController, [
     CONSOLE,
     MANUAL,
@@ -248,7 +248,7 @@ add_task(async function () {
   ok(!OverviewView.isRendering(),
     "Stop rendering overview when a completed recording is selected.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
 
 function testRecordings(controller, expectedBitFlags) {
diff --git a/devtools/client/performance/test/browser_perf-console-record-09.js b/devtools/client/performance/test/browser_perf-console-record-09.js
index 98d5de92364f..06c14faa59ea 100644
--- a/devtools/client/performance/test/browser_perf-console-record-09.js
+++ b/devtools/client/performance/test/browser_perf-console-record-09.js
@@ -14,17 +14,17 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { waitForRecordingStartedEvents } = require("devtools/client/performance/test/helpers/actions");
 const { idleWait } = require("devtools/client/performance/test/helpers/wait-utils");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   info("Starting console.profile()...");
   let started = waitForRecordingStartedEvents(panel, {
@@ -36,10 +36,10 @@ add_task(async function () {
     // in-progress recording is selected, which won't happen
     skipWaitingForViewState: true,
   });
-  await console.profile();
-  await started;
+  yield console.profile();
+  yield started;
 
-  await PerformanceController.clearRecordings();
+  yield PerformanceController.clearRecordings();
   let recordings = PerformanceController.getRecordings();
   is(recordings.length, 1, "One recording found in the performance panel.");
   is(recordings[0].isConsole(), true, "Recording came from console.profile.");
@@ -48,17 +48,17 @@ add_task(async function () {
     "There current recording should be the first one.");
 
   info("Attempting to end console.profileEnd()...");
-  await console.profileEnd();
-  await idleWait(1000);
+  yield console.profileEnd();
+  yield idleWait(1000);
 
   ok(true,
     "Stopping an in-progress console profile after clearing recordings does not throw.");
 
-  await PerformanceController.clearRecordings();
+  yield PerformanceController.clearRecordings();
   recordings = PerformanceController.getRecordings();
   is(recordings.length, 0, "No recordings found");
   is(PerformanceController.getCurrentRecording(), null,
     "There should be no current recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-01-toggle.js b/devtools/client/performance/test/browser_perf-details-01-toggle.js
index fb4211d68e73..8cc7f9e0c9c8 100644
--- a/devtools/client/performance/test/browser_perf-details-01-toggle.js
+++ b/devtools/client/performance/test/browser_perf-details-01-toggle.js
@@ -12,16 +12,16 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { command } = require("devtools/client/performance/test/helpers/input-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, $, DetailsView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   info("Checking views on startup.");
   checkViews(DetailsView, $, "waterfall");
@@ -30,25 +30,25 @@ add_task(async function () {
   let viewChanged = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED,
                          { spreadArgs: true });
   command($("toolbarbutton[data-view='js-calltree']"));
-  let [, viewName] = await viewChanged;
+  let [, viewName] = yield viewChanged;
   is(viewName, "js-calltree", "UI_DETAILS_VIEW_SELECTED fired with view name");
   checkViews(DetailsView, $, "js-calltree");
 
   // Select js flamegraph view.
   viewChanged = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED, { spreadArgs: true });
   command($("toolbarbutton[data-view='js-flamegraph']"));
-  [, viewName] = await viewChanged;
+  [, viewName] = yield viewChanged;
   is(viewName, "js-flamegraph", "UI_DETAILS_VIEW_SELECTED fired with view name");
   checkViews(DetailsView, $, "js-flamegraph");
 
   // Select waterfall view.
   viewChanged = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED, { spreadArgs: true });
   command($("toolbarbutton[data-view='waterfall']"));
-  [, viewName] = await viewChanged;
+  [, viewName] = yield viewChanged;
   is(viewName, "waterfall", "UI_DETAILS_VIEW_SELECTED fired with view name");
   checkViews(DetailsView, $, "waterfall");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
 
 function checkViews(DetailsView, $, currentView) {
diff --git a/devtools/client/performance/test/browser_perf-details-02-utility-fun.js b/devtools/client/performance/test/browser_perf-details-02-utility-fun.js
index 8b0c623f7cdf..5914742ddb0c 100644
--- a/devtools/client/performance/test/browser_perf-details-02-utility-fun.js
+++ b/devtools/client/performance/test/browser_perf-details-02-utility-fun.js
@@ -11,8 +11,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -25,35 +25,35 @@ add_task(async function () {
     JsFlameGraphView
   } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is selected by default in the details view.");
 
   // Select js calltree view.
   let selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
-  await DetailsView.selectView("js-calltree");
-  await selected;
+  yield DetailsView.selectView("js-calltree");
+  yield selected;
 
   ok(DetailsView.isViewSelected(JsCallTreeView),
     "The js calltree view is now selected in the details view.");
 
   // Select js flamegraph view.
   selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
-  await DetailsView.selectView("js-flamegraph");
-  await selected;
+  yield DetailsView.selectView("js-flamegraph");
+  yield selected;
 
   ok(DetailsView.isViewSelected(JsFlameGraphView),
     "The js flamegraph view is now selected in the details view.");
 
   // Select waterfall view.
   selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
-  await DetailsView.selectView("waterfall");
-  await selected;
+  yield DetailsView.selectView("waterfall");
+  yield selected;
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is now selected in the details view.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-03-without-allocations.js b/devtools/client/performance/test/browser_perf-details-03-without-allocations.js
index 5aa9721789db..c69c1de9fa73 100644
--- a/devtools/client/performance/test/browser_perf-details-03-without-allocations.js
+++ b/devtools/client/performance/test/browser_perf-details-03-without-allocations.js
@@ -16,8 +16,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -37,8 +37,8 @@ add_task(async function () {
   // Disable allocations to prevent recording them.
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, false);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is selected by default in the details view.");
@@ -48,8 +48,8 @@ add_task(async function () {
 
   // The toolbar buttons will always be hidden when a recording isn't available,
   // so make sure we have one that's finished.
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is still selected in the details view.");
@@ -62,8 +62,8 @@ add_task(async function () {
   let selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
   let rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
   DetailsView.selectView("memory-calltree");
-  await selected;
-  await rendered;
+  yield selected;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(MemoryCallTreeView),
     "The memory call tree view can now be selected.");
@@ -71,8 +71,8 @@ add_task(async function () {
   selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   DetailsView.selectView("memory-flamegraph");
-  await selected;
-  await rendered;
+  yield selected;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(MemoryFlameGraphView),
     "The memory flamegraph view can now be selected.");
@@ -81,8 +81,8 @@ add_task(async function () {
   selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   setSelectedRecording(panel, 0);
-  await selected;
-  await rendered;
+  yield selected;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(WaterfallView), "The waterfall view is now selected " +
     "when switching back to a recording that does not have memory data.");
@@ -95,7 +95,7 @@ add_task(async function () {
   // Go back to the recording with memory data.
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   setSelectedRecording(panel, 1);
-  await rendered;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is still selected in the details view.");
@@ -108,8 +108,8 @@ add_task(async function () {
   selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
   rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
   DetailsView.selectView("memory-calltree");
-  await selected;
-  await rendered;
+  yield selected;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(MemoryCallTreeView), "The memory call tree view can be " +
     "selected again after going back to the view with memory data.");
@@ -117,11 +117,11 @@ add_task(async function () {
   selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   DetailsView.selectView("memory-flamegraph");
-  await selected;
-  await rendered;
+  yield selected;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(MemoryFlameGraphView), "The memory flamegraph view can " +
     "be selected again after going back to the view with memory data.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-04-toolbar-buttons.js b/devtools/client/performance/test/browser_perf-details-04-toolbar-buttons.js
index 7509216ce81b..9dec9fe7c5ea 100644
--- a/devtools/client/performance/test/browser_perf-details-04-toolbar-buttons.js
+++ b/devtools/client/performance/test/browser_perf-details-04-toolbar-buttons.js
@@ -13,8 +13,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { setSelectedRecording, getSelectedRecordingIndex } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -43,7 +43,7 @@ add_task(async function () {
   is(memCallBtn.hidden, true,
     "The `memory-calltree` button is hidden when tool starts.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(waterfallBtn.hidden, true,
     "The `waterfall` button is hidden when recording starts.");
@@ -56,7 +56,7 @@ add_task(async function () {
   is(memCallBtn.hidden, true,
     "The `memory-calltree` button is hidden when recording starts.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(waterfallBtn.hidden, false,
     "The `waterfall` button is visible when recording ends.");
@@ -69,7 +69,7 @@ add_task(async function () {
   is(memCallBtn.hidden, true,
     "The `memory-calltree` button is hidden when recording ends.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(waterfallBtn.hidden, true,
     "The `waterfall` button is hidden when another recording starts.");
@@ -85,8 +85,8 @@ add_task(async function () {
   let selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   let rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   setSelectedRecording(panel, 0);
-  await selected;
-  await rendered;
+  yield selected;
+  yield rendered;
 
   let selectedIndex = getSelectedRecordingIndex(panel);
   is(selectedIndex, 0,
@@ -105,7 +105,7 @@ add_task(async function () {
 
   selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 1);
-  await selected;
+  yield selected;
 
   selectedIndex = getSelectedRecordingIndex(panel);
   is(selectedIndex, 1,
@@ -123,8 +123,8 @@ add_task(async function () {
     "The `memory-calltree button` still is hidden when second recording selected.");
 
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
-  await stopRecording(panel);
-  await rendered;
+  yield stopRecording(panel);
+  yield rendered;
 
   selectedIndex = getSelectedRecordingIndex(panel);
   is(selectedIndex, 1,
@@ -141,5 +141,5 @@ add_task(async function () {
   is(memCallBtn.hidden, true,
     "The `memory-calltree` button is hidden when second recording finished.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-05-preserve-view.js b/devtools/client/performance/test/browser_perf-details-05-preserve-view.js
index 7f13417716a4..00c71db7e7ec 100644
--- a/devtools/client/performance/test/browser_perf-details-05-preserve-view.js
+++ b/devtools/client/performance/test/browser_perf-details-05-preserve-view.js
@@ -12,33 +12,33 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, PerformanceController, DetailsView, JsCallTreeView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let selected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await selected;
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield selected;
+  yield rendered;
 
   ok(DetailsView.isViewSelected(JsCallTreeView),
     "The js calltree view is now selected in the details view.");
 
   let cleared = once(PerformanceController, EVENTS.RECORDING_SELECTED,
                      { expectedArgs: { "1": null } });
-  await PerformanceController.clearRecordings();
-  await cleared;
+  yield PerformanceController.clearRecordings();
+  yield cleared;
 
-  await startRecording(panel);
-  await stopRecording(panel, {
+  yield startRecording(panel);
+  yield stopRecording(panel, {
     expectedViewClass: "JsCallTreeView",
     expectedViewEvent: "UI_JS_CALL_TREE_RENDERED"
   });
@@ -46,5 +46,5 @@ add_task(async function () {
   ok(DetailsView.isViewSelected(JsCallTreeView),
     "The js calltree view is still selected in the details view.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-06-rerender-on-selection.js b/devtools/client/performance/test/browser_perf-details-06-rerender-on-selection.js
index 79b6a533844c..abe2dfc75acb 100644
--- a/devtools/client/performance/test/browser_perf-details-06-rerender-on-selection.js
+++ b/devtools/client/performance/test/browser_perf-details-06-rerender-on-selection.js
@@ -13,8 +13,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { scrollCanvasGraph, HORIZONTAL_AXIS } = require("devtools/client/performance/test/helpers/input-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -28,24 +28,24 @@ add_task(async function () {
     JsFlameGraphView
   } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let waterfallRendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.setTimeInterval({ startTime: 10, endTime: 20 });
-  await waterfallRendered;
+  yield waterfallRendered;
 
   // Select the call tree to make sure it's initialized and ready to receive
   // redrawing requests once reselected.
   let callTreeRendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await callTreeRendered;
+  yield DetailsView.selectView("js-calltree");
+  yield callTreeRendered;
 
   // Switch to the flamegraph and perform a scroll over the visualization.
   // The waterfall and call tree should get rerendered when reselected.
   let flamegraphRendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await flamegraphRendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield flamegraphRendered;
 
   let overviewRangeSelected = once(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED);
   let waterfallRerendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
@@ -64,16 +64,16 @@ add_task(async function () {
     x: 10
   });
 
-  await overviewRangeSelected;
+  yield overviewRangeSelected;
   ok(true, "Overview range was changed.");
 
-  await DetailsView.selectView("waterfall");
-  await waterfallRerendered;
+  yield DetailsView.selectView("waterfall");
+  yield waterfallRerendered;
   ok(true, "Waterfall rerendered by flame graph changing interval.");
 
-  await DetailsView.selectView("js-calltree");
-  await callTreeRerendered;
+  yield DetailsView.selectView("js-calltree");
+  yield callTreeRerendered;
   ok(true, "CallTree rerendered by flame graph changing interval.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-07-bleed-events.js b/devtools/client/performance/test/browser_perf-details-07-bleed-events.js
index 4b0c4a77c5fb..f299aadad744 100644
--- a/devtools/client/performance/test/browser_perf-details-07-bleed-events.js
+++ b/devtools/client/performance/test/browser_perf-details-07-bleed-events.js
@@ -11,38 +11,38 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, DetailsView, JsCallTreeView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   // The waterfall should render by default, and we want to make
   // sure that the render events don't bleed between detail views
   // so test that's the case after both views have been created.
   let callTreeRendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await callTreeRendered;
+  yield DetailsView.selectView("js-calltree");
+  yield callTreeRendered;
 
   let waterfallSelected = once(DetailsView, EVENTS.UI_DETAILS_VIEW_SELECTED);
-  await DetailsView.selectView("waterfall");
-  await waterfallSelected;
+  yield DetailsView.selectView("waterfall");
+  yield waterfallSelected;
 
   once(JsCallTreeView, EVENTS.UI_WATERFALL_RENDERED).then(() =>
     ok(false, "JsCallTreeView should not receive UI_WATERFALL_RENDERED event."));
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let callTreeRerendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await callTreeRerendered;
+  yield DetailsView.selectView("js-calltree");
+  yield callTreeRerendered;
 
   ok(true, "Test passed.");
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-render-00-waterfall.js b/devtools/client/performance/test/browser_perf-details-render-00-waterfall.js
index b1738fb27b40..5f65fa00dc7c 100644
--- a/devtools/client/performance/test/browser_perf-details-render-00-waterfall.js
+++ b/devtools/client/performance/test/browser_perf-details-render-00-waterfall.js
@@ -10,31 +10,31 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { DetailsView, WaterfallView } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   // Already waits for EVENTS.UI_WATERFALL_RENDERED.
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is selected by default in the details view.");
 
   ok(true, "WaterfallView rendered after recording is stopped.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
   // Already waits for EVENTS.UI_WATERFALL_RENDERED.
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   ok(DetailsView.isViewSelected(WaterfallView),
     "The waterfall view is still selected in the details view.");
 
   ok(true, "WaterfallView rendered again after recording completed a second time.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-render-01-js-calltree.js b/devtools/client/performance/test/browser_perf-details-render-01-js-calltree.js
index 66b412f2adf5..bc191f2fccf5 100644
--- a/devtools/client/performance/test/browser_perf-details-render-01-js-calltree.js
+++ b/devtools/client/performance/test/browser_perf-details-render-01-js-calltree.js
@@ -11,30 +11,30 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, DetailsView, JsCallTreeView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
 
   ok(true, "JsCallTreeView rendered after recording is stopped.");
 
-  await startRecording(panel);
-  await stopRecording(panel, {
+  yield startRecording(panel);
+  yield stopRecording(panel, {
     expectedViewClass: "JsCallTreeView",
     expectedViewEvent: "UI_JS_CALL_TREE_RENDERED"
   });
 
   ok(true, "JsCallTreeView rendered again after recording completed a second time.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-render-02-js-flamegraph.js b/devtools/client/performance/test/browser_perf-details-render-02-js-flamegraph.js
index 2ca5e816ef9c..e5e74fc7c109 100644
--- a/devtools/client/performance/test/browser_perf-details-render-02-js-flamegraph.js
+++ b/devtools/client/performance/test/browser_perf-details-render-02-js-flamegraph.js
@@ -11,30 +11,30 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, DetailsView, JsFlameGraphView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield rendered;
 
   ok(true, "JsFlameGraphView rendered after recording is stopped.");
 
-  await startRecording(panel);
-  await stopRecording(panel, {
+  yield startRecording(panel);
+  yield stopRecording(panel, {
     expectedViewClass: "JsFlameGraphView",
     expectedViewEvent: "UI_JS_FLAMEGRAPH_RENDERED"
   });
 
   ok(true, "JsFlameGraphView rendered again after recording completed a second time.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-render-03-memory-calltree.js b/devtools/client/performance/test/browser_perf-details-render-03-memory-calltree.js
index 0228c9c8b3a4..758dea8c657d 100644
--- a/devtools/client/performance/test/browser_perf-details-render-03-memory-calltree.js
+++ b/devtools/client/performance/test/browser_perf-details-render-03-memory-calltree.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -23,22 +23,22 @@ add_task(async function () {
   // Enable allocations to test.
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
-  await DetailsView.selectView("memory-calltree");
-  await rendered;
+  yield DetailsView.selectView("memory-calltree");
+  yield rendered;
 
   ok(true, "MemoryCallTreeView rendered after recording is stopped.");
 
-  await startRecording(panel);
-  await stopRecording(panel, {
+  yield startRecording(panel);
+  yield stopRecording(panel, {
     expectedViewClass: "MemoryCallTreeView",
     expectedViewEvent: "UI_MEMORY_CALL_TREE_RENDERED"
   });
 
   ok(true, "MemoryCallTreeView rendered again after recording completed a second time.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-details-render-04-memory-flamegraph.js b/devtools/client/performance/test/browser_perf-details-render-04-memory-flamegraph.js
index d5f9011a4890..119f090e5ff9 100644
--- a/devtools/client/performance/test/browser_perf-details-render-04-memory-flamegraph.js
+++ b/devtools/client/performance/test/browser_perf-details-render-04-memory-flamegraph.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -23,17 +23,17 @@ add_task(async function () {
   // Enable allocations to test.
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("memory-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("memory-flamegraph");
+  yield rendered;
 
   ok(true, "MemoryFlameGraphView rendered after recording is stopped.");
 
-  await startRecording(panel);
-  await stopRecording(panel, {
+  yield startRecording(panel);
+  yield stopRecording(panel, {
     expectedViewClass: "MemoryFlameGraphView",
     expectedViewEvent: "UI_MEMORY_FLAMEGRAPH_RENDERED"
   });
@@ -41,5 +41,5 @@ add_task(async function () {
   ok(true,
     "MemoryFlameGraphView rendered again after recording completed a second time.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-docload.js b/devtools/client/performance/test/browser_perf-docload.js
index 68c888c4d174..b92a8cfbdd13 100644
--- a/devtools/client/performance/test/browser_perf-docload.js
+++ b/devtools/client/performance/test/browser_perf-docload.js
@@ -11,18 +11,18 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording, reload } = require("devtools/client/performance/test/helpers/actions");
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 
-add_task(async function () {
-  let { panel, target } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel, target } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
-  await reload(target);
+  yield startRecording(panel);
+  yield reload(target);
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     // Wait until we get the necessary markers.
     let markers = PerformanceController.getCurrentRecording().getMarkers();
     if (!markers.some(m => m.name == "document::DOMContentLoaded") ||
@@ -38,6 +38,6 @@ add_task(async function () {
     return true;
   });
 
-  await stopRecording(panel);
-  await teardownToolboxAndRemoveTab(panel);
+  yield stopRecording(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-gc-snap.js b/devtools/client/performance/test/browser_perf-gc-snap.js
index 4d147e1195ca..57589825ec95 100644
--- a/devtools/client/performance/test/browser_perf-gc-snap.js
+++ b/devtools/client/performance/test/browser_perf-gc-snap.js
@@ -6,23 +6,23 @@
  * Tests that the marker details on GC markers displays allocation
  * buttons and snaps to the correct range
  */
-async function spawnTest() {
-  let { panel } = await initPerformance(ALLOCS_URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(ALLOCS_URL);
   let { $, $$, EVENTS, PerformanceController, OverviewView, DetailsView, WaterfallView, MemoryCallTreeView } = panel.panelWin;
   let EPSILON = 0.00001;
 
   Services.prefs.setBoolPref(ALLOCATIONS_PREF, true);
 
-  await startRecording(panel);
-  await idleWait(1000);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield idleWait(1000);
+  yield stopRecording(panel);
 
   injectGCMarkers(PerformanceController, WaterfallView);
 
   // Select everything
   let rendered = WaterfallView.once(EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.setTimeInterval({ startTime: 0, endTime: Number.MAX_VALUE });
-  await rendered;
+  yield rendered;
 
   let bars = $$(".waterfall-marker-bar");
   let gcMarkers = PerformanceController.getCurrentRecording().getMarkers();
@@ -39,12 +39,12 @@ async function spawnTest() {
   EventUtils.sendMouseEvent({ type: "mousedown" }, targetBar);
   let showAllocsButton;
   // On slower machines this can not be found immediately?
-  await waitUntil(() => showAllocsButton = $("#waterfall-details .custom-button[type='show-allocations']"));
+  yield waitUntil(() => showAllocsButton = $("#waterfall-details .custom-button[type='show-allocations']"));
   ok(showAllocsButton, "GC buttons when allocations are enabled");
 
   rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
   EventUtils.sendMouseEvent({ type: "click" }, showAllocsButton);
-  await rendered;
+  yield rendered;
 
   is(OverviewView.getTimeInterval().startTime, 0, "When clicking first GC, should use 0 as start time");
   within(OverviewView.getTimeInterval().endTime, targetMarker.start, EPSILON, "Correct end time range");
@@ -52,8 +52,8 @@ async function spawnTest() {
   let duration = PerformanceController.getCurrentRecording().getDuration();
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.setTimeInterval({ startTime: 0, endTime: duration });
-  await DetailsView.selectView("waterfall");
-  await rendered;
+  yield DetailsView.selectView("waterfall");
+  yield rendered;
 
   /**
    * Check when there is a previous GC cycle
@@ -66,12 +66,12 @@ async function spawnTest() {
   info(`Clicking GC Marker of type ${targetMarker.causeName} ${targetMarker.start}:${targetMarker.end}`);
   EventUtils.sendMouseEvent({ type: "mousedown" }, targetBar);
   // On slower machines this can not be found immediately?
-  await waitUntil(() => showAllocsButton = $("#waterfall-details .custom-button[type='show-allocations']"));
+  yield waitUntil(() => showAllocsButton = $("#waterfall-details .custom-button[type='show-allocations']"));
   ok(showAllocsButton, "GC buttons when allocations are enabled");
 
   rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
   EventUtils.sendMouseEvent({ type: "click" }, showAllocsButton);
-  await rendered;
+  yield rendered;
 
   within(OverviewView.getTimeInterval().startTime, gcMarkers[2].end, EPSILON,
     "selection start range is last marker from previous GC cycle.");
@@ -87,20 +87,20 @@ async function spawnTest() {
   duration = PerformanceController.getCurrentRecording().getDuration();
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.setTimeInterval({ startTime: 0, endTime: duration });
-  await rendered;
+  yield rendered;
 
   Services.prefs.setBoolPref(ALLOCATIONS_PREF, false);
-  await startRecording(panel);
+  yield startRecording(panel);
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
-  await stopRecording(panel);
-  await rendered;
+  yield stopRecording(panel);
+  yield rendered;
 
   injectGCMarkers(PerformanceController, WaterfallView);
 
   // Select everything
   rendered = WaterfallView.once(EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.setTimeInterval({ startTime: 0, endTime: Number.MAX_VALUE });
-  await rendered;
+  yield rendered;
 
   ok(true, "WaterfallView rendered after recording is stopped.");
 
@@ -112,7 +112,7 @@ async function spawnTest() {
   ok(!showAllocsButton, "No GC buttons when allocations are disabled");
 
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/performance/test/browser_perf-highlighted.js b/devtools/client/performance/test/browser_perf-highlighted.js
index 3af658963c9e..111747ce0296 100644
--- a/devtools/client/performance/test/browser_perf-highlighted.js
+++ b/devtools/client/performance/test/browser_perf-highlighted.js
@@ -12,37 +12,37 @@ const { initPerformanceInTab, initConsoleInNewTab, teardownToolboxAndRemoveTab }
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 
-add_task(async function () {
-  let { target, toolbox, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, toolbox, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let tab = toolbox.doc.getElementById("toolbox-tab-performance");
 
-  await console.profile("rust");
-  await waitUntil(() => tab.classList.contains("highlighted"));
+  yield console.profile("rust");
+  yield waitUntil(() => tab.classList.contains("highlighted"));
 
   ok(tab.classList.contains("highlighted"), "Performance tab is highlighted during " +
     "recording from console.profile when unloaded.");
 
-  await console.profileEnd("rust");
-  await waitUntil(() => !tab.classList.contains("highlighted"));
+  yield console.profileEnd("rust");
+  yield waitUntil(() => !tab.classList.contains("highlighted"));
 
   ok(!tab.classList.contains("highlighted"),
     "Performance tab is no longer highlighted when console.profile recording finishes.");
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   ok(tab.classList.contains("highlighted"),
     "Performance tab is highlighted during recording while in performance tool.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   ok(!tab.classList.contains("highlighted"),
     "Performance tab is no longer highlighted when recording finishes.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-loading-01.js b/devtools/client/performance/test/browser_perf-loading-01.js
index 70486e6c8b53..d732efcae471 100644
--- a/devtools/client/performance/test/browser_perf-loading-01.js
+++ b/devtools/client/performance/test/browser_perf-loading-01.js
@@ -13,15 +13,15 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecording, getDurationLabelText } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, L10N, PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(getDurationLabelText(panel, 0),
     L10N.getStr("recordingsList.recordingLabel"),
@@ -35,18 +35,18 @@ add_task(async function () {
   });
   let everythingStopped = stopRecording(panel);
 
-  await recordingStopping;
+  yield recordingStopping;
   is(getDurationLabelText(panel, 0),
     L10N.getStr("recordingsList.loadingLabel"),
     "The duration node should show the 'loading' message while stopping");
 
-  await recordingStopped;
+  yield recordingStopped;
   const selected = getSelectedRecording(panel);
   is(getDurationLabelText(panel, 0),
     L10N.getFormatStr("recordingsList.durationLabel",
     selected.getDuration().toFixed(0)),
     "The duration node should show the duration after the record has stopped");
 
-  await everythingStopped;
-  await teardownToolboxAndRemoveTab(panel);
+  yield everythingStopped;
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-loading-02.js b/devtools/client/performance/test/browser_perf-loading-02.js
index df20138e89bb..c860cb7a9d73 100644
--- a/devtools/client/performance/test/browser_perf-loading-02.js
+++ b/devtools/client/performance/test/browser_perf-loading-02.js
@@ -15,8 +15,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecordingIndex, setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -27,7 +27,7 @@ add_task(async function () {
   let loadingNotice = $("#loading-notice");
   let detailsPane = $("#details-pane");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(detailsContainer.selectedPanel, recordingNotice,
     "The recording-notice is shown while recording.");
@@ -40,21 +40,21 @@ add_task(async function () {
   });
   let everythingStopped = stopRecording(panel);
 
-  await recordingStopping;
+  yield recordingStopping;
   is(detailsContainer.selectedPanel, loadingNotice,
     "The loading-notice is shown while the record is stopping.");
 
-  await recordingStopped;
+  yield recordingStopped;
   is(detailsContainer.selectedPanel, detailsPane,
     "The details panel is shown after the record has stopped.");
 
-  await everythingStopped;
-  await startRecording(panel);
+  yield everythingStopped;
+  yield startRecording(panel);
 
   info("While the 2nd record is still going, switch to the first one.");
   let recordingSelected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await recordingSelected;
+  yield recordingSelected;
 
   recordingStopping = once(PerformanceController, EVENTS.RECORDING_STATE_CHANGE, {
     expectedArgs: { "1": "recording-stopping" }
@@ -64,19 +64,19 @@ add_task(async function () {
   });
   everythingStopped = stopRecording(panel);
 
-  await recordingStopping;
+  yield recordingStopping;
   is(detailsContainer.selectedPanel, detailsPane,
     "The details panel is still shown while the 2nd record is being stopped.");
   is(getSelectedRecordingIndex(panel), 0,
     "The first record is still selected.");
 
-  await recordingStopped;
+  yield recordingStopped;
 
   is(detailsContainer.selectedPanel, detailsPane,
     "The details panel is still shown after the 2nd record has stopped.");
   is(getSelectedRecordingIndex(panel), 1,
     "The second record is now selected.");
 
-  await everythingStopped;
-  await teardownToolboxAndRemoveTab(panel);
+  yield everythingStopped;
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-marker-details.js b/devtools/client/performance/test/browser_perf-marker-details.js
index 8286918eec64..7a5447d6a9c7 100644
--- a/devtools/client/performance/test/browser_perf-marker-details.js
+++ b/devtools/client/performance/test/browser_perf-marker-details.js
@@ -7,8 +7,8 @@
  * for each marker.
  */
 
-async function spawnTest() {
-  let { target, panel } = await initPerformance(MARKERS_URL);
+function* spawnTest() {
+  let { target, panel } = yield initPerformance(MARKERS_URL);
   let { $, $$, EVENTS, PerformanceController, OverviewView, WaterfallView } = panel.panelWin;
 
   // Hijack the markers massaging part of creating the waterfall view,
@@ -23,16 +23,16 @@ async function spawnTest() {
     "Styles", "Reflow", "ConsoleTime", "TimeStamp"
   ];
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     // Wait until we get all the different markers.
     let markers = PerformanceController.getCurrentRecording().getMarkers();
     return MARKER_TYPES.every(type => markers.some(m => m.name === type));
   });
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   info("No need to select everything in the timeline.");
@@ -127,7 +127,7 @@ async function spawnTest() {
     }
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/performance/test/browser_perf-options-01-toggle-throw.js b/devtools/client/performance/test/browser_perf-options-01-toggle-throw.js
index f81310019ea0..4ecfb41524bb 100644
--- a/devtools/client/performance/test/browser_perf-options-01-toggle-throw.js
+++ b/devtools/client/performance/test/browser_perf-options-01-toggle-throw.js
@@ -9,15 +9,15 @@
 const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { DetailsView, JsCallTreeView } = panel.panelWin;
 
-  await DetailsView.selectView("js-calltree");
+  yield DetailsView.selectView("js-calltree");
 
   // Manually call the _onPrefChanged function so we can catch an error.
   try {
@@ -27,5 +27,5 @@ add_task(async function () {
     ok(false, "Toggling preferences before there are any recordings should not fail.");
   }
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-02-toggle-throw-alt.js b/devtools/client/performance/test/browser_perf-options-02-toggle-throw-alt.js
index af63ad17ecd8..cdea1556a6cf 100644
--- a/devtools/client/performance/test/browser_perf-options-02-toggle-throw-alt.js
+++ b/devtools/client/performance/test/browser_perf-options-02-toggle-throw-alt.js
@@ -10,16 +10,16 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { DetailsView, JsCallTreeView } = panel.panelWin;
 
-  await DetailsView.selectView("js-calltree");
-  await startRecording(panel);
+  yield DetailsView.selectView("js-calltree");
+  yield startRecording(panel);
 
   // Manually call the _onPrefChanged function so we can catch an error.
   try {
@@ -29,10 +29,10 @@ add_task(async function () {
     ok(false, "Toggling preferences during a recording should not fail.");
   }
 
-  await stopRecording(panel, {
+  yield stopRecording(panel, {
     expectedViewClass: "JsCallTreeView",
     expectedViewEvent: "UI_JS_CALL_TREE_RENDERED"
   });
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-03-toggle-meta.js b/devtools/client/performance/test/browser_perf-options-03-toggle-meta.js
index 854b0371844b..384133fff37a 100644
--- a/devtools/client/performance/test/browser_perf-options-03-toggle-meta.js
+++ b/devtools/client/performance/test/browser_perf-options-03-toggle-meta.js
@@ -10,10 +10,10 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { UI_EXPERIMENTAL_PREF } = require("devtools/client/performance/test/helpers/prefs");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setBoolPref(UI_EXPERIMENTAL_PREF, false);
 
-  let { panel } = await initPerformanceInNewTab({
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -34,5 +34,5 @@ add_task(async function () {
   ok($menu.classList.contains("experimental-enabled"),
     "The menu popup has `experimental-enabled` after toggle.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-enable-framerate-01.js b/devtools/client/performance/test/browser_perf-options-enable-framerate-01.js
index 7c7b1e8a297b..ad75db6cfbe9 100644
--- a/devtools/client/performance/test/browser_perf-options-enable-framerate-01.js
+++ b/devtools/client/performance/test/browser_perf-options-enable-framerate-01.js
@@ -13,8 +13,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { isVisible } = require("devtools/client/performance/test/helpers/dom-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,8 +24,8 @@ add_task(async function () {
   // Disable framerate to test.
   Services.prefs.setBoolPref(UI_ENABLE_FRAMERATE_PREF, false);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withTicks, false,
     "PerformanceFront started without ticks recording.");
@@ -40,13 +40,13 @@ add_task(async function () {
   ok(!isVisible($("#time-framerate")),
     "The fps graph is still hidden if recording does not contain ticks.");
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withTicks, true,
     "PerformanceFront started with ticks recording.");
   ok(isVisible($("#time-framerate")),
     "The fps graph is not hidden when ticks enabled before recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-enable-framerate-02.js b/devtools/client/performance/test/browser_perf-options-enable-framerate-02.js
index b0573e8c9f5d..b7f870bba985 100644
--- a/devtools/client/performance/test/browser_perf-options-enable-framerate-02.js
+++ b/devtools/client/performance/test/browser_perf-options-enable-framerate-02.js
@@ -12,8 +12,8 @@ const { UI_ENABLE_FRAMERATE_PREF } = require("devtools/client/performance/test/h
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,22 +22,22 @@ add_task(async function () {
 
   // Test starting without framerate, and stopping with it.
   Services.prefs.setBoolPref(UI_ENABLE_FRAMERATE_PREF, false);
-  await startRecording(panel);
+  yield startRecording(panel);
 
   Services.prefs.setBoolPref(UI_ENABLE_FRAMERATE_PREF, true);
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withTicks, false,
     "The recording finished without tracking framerate.");
 
   // Test starting with framerate, and stopping without it.
-  await startRecording(panel);
+  yield startRecording(panel);
 
   Services.prefs.setBoolPref(UI_ENABLE_FRAMERATE_PREF, false);
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withTicks, true,
     "The recording finished with tracking framerate.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-enable-memory-01.js b/devtools/client/performance/test/browser_perf-options-enable-memory-01.js
index c421fe7a76ca..9785d54d60c4 100644
--- a/devtools/client/performance/test/browser_perf-options-enable-memory-01.js
+++ b/devtools/client/performance/test/browser_perf-options-enable-memory-01.js
@@ -13,8 +13,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { isVisible } = require("devtools/client/performance/test/helpers/dom-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,8 +24,8 @@ add_task(async function () {
   // Disable memory to test.
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, false);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withMemory, false,
     "PerformanceFront started without memory recording.");
@@ -44,8 +44,8 @@ add_task(async function () {
   ok(!isVisible($("#memory-overview")), "memory graph is still hidden after enabling " +
                                         "if recording did not start recording memory");
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withMemory, true,
     "PerformanceFront started with memory recording.");
@@ -54,5 +54,5 @@ add_task(async function () {
   ok(isVisible($("#memory-overview")),
     "The memory graph is not hidden when memory enabled before recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-enable-memory-02.js b/devtools/client/performance/test/browser_perf-options-enable-memory-02.js
index fab4b89ec7aa..b9c5776875a0 100644
--- a/devtools/client/performance/test/browser_perf-options-enable-memory-02.js
+++ b/devtools/client/performance/test/browser_perf-options-enable-memory-02.js
@@ -12,8 +12,8 @@ const { UI_ENABLE_MEMORY_PREF } = require("devtools/client/performance/test/help
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,10 +22,10 @@ add_task(async function () {
 
   // Test starting without memory, and stopping with it.
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, false);
-  await startRecording(panel);
+  yield startRecording(panel);
 
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, true);
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withMemory, false,
     "The recording finished without tracking memory.");
@@ -34,10 +34,10 @@ add_task(async function () {
     "The recording finished without tracking allocations.");
 
   // Test starting with memory, and stopping without it.
-  await startRecording(panel);
+  yield startRecording(panel);
 
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, false);
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceController.getCurrentRecording().getConfiguration().withMemory, true,
     "The recording finished with tracking memory.");
@@ -45,5 +45,5 @@ add_task(async function () {
     false,
     "The recording still is not recording allocations.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-01.js b/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-01.js
index f71ce9d51207..9fccd619949c 100644
--- a/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-01.js
+++ b/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-01.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -28,12 +28,12 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_FLATTEN_RECURSION_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield rendered;
 
   let thread1 = PerformanceController.getCurrentRecording().getProfile().threads[0];
   let rendering1 = FlameGraphUtils._cache.get(thread1);
@@ -45,7 +45,7 @@ add_task(async function () {
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_FLATTEN_RECURSION_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling flatten-tree-recursion.");
 
   let thread2 = PerformanceController.getCurrentRecording().getProfile().threads[0];
@@ -58,7 +58,7 @@ add_task(async function () {
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_FLATTEN_RECURSION_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling back flatten-tree-recursion.");
 
   let thread3 = PerformanceController.getCurrentRecording().getProfile().threads[0];
@@ -69,5 +69,5 @@ add_task(async function () {
   isnot(rendering2, rendering3,
     "The rendering data should be different because other options were used (2).");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-02.js b/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-02.js
index fefff47a7e1c..509dd0f666a7 100644
--- a/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-02.js
+++ b/devtools/client/performance/test/browser_perf-options-flatten-tree-recursion-02.js
@@ -13,8 +13,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -32,12 +32,12 @@ add_task(async function () {
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
   Services.prefs.setBoolPref(UI_FLATTEN_RECURSION_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("memory-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("memory-flamegraph");
+  yield rendered;
 
   let allocations1 = PerformanceController.getCurrentRecording().getAllocations();
   let thread1 = RecordingUtils.getProfileThreadFromAllocations(allocations1);
@@ -52,7 +52,7 @@ add_task(async function () {
 
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_FLATTEN_RECURSION_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryFlameGraphView rerendered when toggling flatten-tree-recursion.");
 
   let allocations2 = PerformanceController.getCurrentRecording().getAllocations();
@@ -68,7 +68,7 @@ add_task(async function () {
 
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_FLATTEN_RECURSION_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryFlameGraphView rerendered when toggling back flatten-tree-recursion.");
 
   let allocations3 = PerformanceController.getCurrentRecording().getAllocations();
@@ -82,5 +82,5 @@ add_task(async function () {
   isnot(rendering2, rendering3,
     "The rendering data should be different because other options were used (2).");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-invert-call-tree-01.js b/devtools/client/performance/test/browser_perf-options-invert-call-tree-01.js
index a40a39ca5e10..cd84e8754351 100644
--- a/devtools/client/performance/test/browser_perf-options-invert-call-tree-01.js
+++ b/devtools/client/performance/test/browser_perf-options-invert-call-tree-01.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,22 +22,22 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_INVERT_CALL_TREE_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_CALL_TREE_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "JsCallTreeView rerendered when toggling invert-call-tree.");
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_CALL_TREE_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "JsCallTreeView rerendered when toggling back invert-call-tree.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-invert-call-tree-02.js b/devtools/client/performance/test/browser_perf-options-invert-call-tree-02.js
index 551ba8251091..ae0c8ede8b52 100644
--- a/devtools/client/performance/test/browser_perf-options-invert-call-tree-02.js
+++ b/devtools/client/performance/test/browser_perf-options-invert-call-tree-02.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,22 +24,22 @@ add_task(async function () {
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
   Services.prefs.setBoolPref(UI_INVERT_CALL_TREE_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
-  await DetailsView.selectView("memory-calltree");
-  await rendered;
+  yield DetailsView.selectView("memory-calltree");
+  yield rendered;
 
   rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_CALL_TREE_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryCallTreeView rerendered when toggling invert-call-tree.");
 
   rendered = once(MemoryCallTreeView, EVENTS.UI_MEMORY_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_CALL_TREE_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryCallTreeView rerendered when toggling back invert-call-tree.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-invert-flame-graph-01.js b/devtools/client/performance/test/browser_perf-options-invert-flame-graph-01.js
index 865958f3e125..ee009bacfb12 100644
--- a/devtools/client/performance/test/browser_perf-options-invert-flame-graph-01.js
+++ b/devtools/client/performance/test/browser_perf-options-invert-flame-graph-01.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,22 +22,22 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_INVERT_FLAME_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield rendered;
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_FLAME_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling invert-call-tree.");
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_FLAME_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling back invert-call-tree.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-invert-flame-graph-02.js b/devtools/client/performance/test/browser_perf-options-invert-flame-graph-02.js
index 8f1493a7de7d..0a93225477d4 100644
--- a/devtools/client/performance/test/browser_perf-options-invert-flame-graph-02.js
+++ b/devtools/client/performance/test/browser_perf-options-invert-flame-graph-02.js
@@ -13,8 +13,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -25,22 +25,22 @@ add_task(async function () {
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
   Services.prefs.setBoolPref(UI_INVERT_FLAME_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("memory-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("memory-flamegraph");
+  yield rendered;
 
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_FLAME_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryFlameGraphView rerendered when toggling invert-call-tree.");
 
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_INVERT_FLAME_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryFlameGraphView rerendered when toggling back invert-call-tree.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-propagate-allocations.js b/devtools/client/performance/test/browser_perf-options-propagate-allocations.js
index e246bc6234de..509452be4ae9 100644
--- a/devtools/client/performance/test/browser_perf-options-propagate-allocations.js
+++ b/devtools/client/performance/test/browser_perf-options-propagate-allocations.js
@@ -12,8 +12,8 @@ const { MEMORY_SAMPLE_PROB_PREF, MEMORY_MAX_LOG_LEN_PREF, UI_ENABLE_ALLOCATIONS_
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel, toolbox } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel, toolbox } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -23,14 +23,14 @@ add_task(async function () {
   Services.prefs.setCharPref(MEMORY_SAMPLE_PROB_PREF, "0.213");
   Services.prefs.setIntPref(MEMORY_MAX_LOG_LEN_PREF, 777777);
 
-  await startRecording(panel);
-  let { probability, maxLogLength } = await toolbox.performance.getConfiguration();
-  await stopRecording(panel);
+  yield startRecording(panel);
+  let { probability, maxLogLength } = yield toolbox.performance.getConfiguration();
+  yield stopRecording(panel);
 
   is(probability, 0.213,
     "The allocations probability option is set on memory actor.");
   is(maxLogLength, 777777,
     "The allocations max log length option is set on memory actor.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-propagate-profiler.js b/devtools/client/performance/test/browser_perf-options-propagate-profiler.js
index c0e908f9d815..d592330517a1 100644
--- a/devtools/client/performance/test/browser_perf-options-propagate-profiler.js
+++ b/devtools/client/performance/test/browser_perf-options-propagate-profiler.js
@@ -12,8 +12,8 @@ const { PROFILER_BUFFER_SIZE_PREF, PROFILER_SAMPLE_RATE_PREF } = require("devtoo
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel, toolbox } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel, toolbox } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -21,12 +21,12 @@ add_task(async function () {
   Services.prefs.setIntPref(PROFILER_BUFFER_SIZE_PREF, 1000);
   Services.prefs.setIntPref(PROFILER_SAMPLE_RATE_PREF, 2);
 
-  await startRecording(panel);
-  let { entries, interval } = await toolbox.performance.getConfiguration();
-  await stopRecording(panel);
+  yield startRecording(panel);
+  let { entries, interval } = yield toolbox.performance.getConfiguration();
+  yield stopRecording(panel);
 
   is(entries, 1000, "profiler entries option is set on profiler");
   is(interval, 0.5, "profiler interval option is set on profiler");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-show-idle-blocks-01.js b/devtools/client/performance/test/browser_perf-options-show-idle-blocks-01.js
index 67a3ab31b081..8c59ede4210a 100644
--- a/devtools/client/performance/test/browser_perf-options-show-idle-blocks-01.js
+++ b/devtools/client/performance/test/browser_perf-options-show-idle-blocks-01.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,22 +22,22 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_SHOW_IDLE_BLOCKS_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield rendered;
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_IDLE_BLOCKS_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling show-idle-blocks.");
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_IDLE_BLOCKS_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling back show-idle-blocks.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-show-idle-blocks-02.js b/devtools/client/performance/test/browser_perf-options-show-idle-blocks-02.js
index 47af07e40046..3e0146ac74a0 100644
--- a/devtools/client/performance/test/browser_perf-options-show-idle-blocks-02.js
+++ b/devtools/client/performance/test/browser_perf-options-show-idle-blocks-02.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,22 +24,22 @@ add_task(async function () {
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
   Services.prefs.setBoolPref(UI_SHOW_IDLE_BLOCKS_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("memory-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("memory-flamegraph");
+  yield rendered;
 
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_IDLE_BLOCKS_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryFlameGraphView rerendered when toggling show-idle-blocks.");
 
   rendered = once(MemoryFlameGraphView, EVENTS.UI_MEMORY_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_IDLE_BLOCKS_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "MemoryFlameGraphView rerendered when toggling back show-idle-blocks.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-show-jit-optimizations.js b/devtools/client/performance/test/browser_perf-options-show-jit-optimizations.js
index dea3dd63e205..fd0bbc663ba4 100644
--- a/devtools/client/performance/test/browser_perf-options-show-jit-optimizations.js
+++ b/devtools/client/performance/test/browser_perf-options-show-jit-optimizations.js
@@ -12,8 +12,8 @@ requestLongerTimeout(2);
  const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 Services.prefs.setBoolPref(INVERT_PREF, false);
 
-async function spawnTest() {
-  let { panel } = await initPerformance(SIMPLE_URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(SIMPLE_URL);
   let { EVENTS, $, $$, window, PerformanceController } = panel.panelWin;
   let { OverviewView, DetailsView, OptimizationsListView, JsCallTreeView } = panel.panelWin;
 
@@ -25,72 +25,72 @@ async function spawnTest() {
 
   // Make two recordings, so we have one to switch to later, as the
   // second one will have fake sample data
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await DetailsView.selectView("js-calltree");
+  yield DetailsView.selectView("js-calltree");
 
-  await injectAndRenderProfilerData();
+  yield injectAndRenderProfilerData();
 
   is($("#jit-optimizations-view").classList.contains("hidden"), true,
     "JIT Optimizations should be hidden when pref is on, but no frame selected");
 
   // A is never a leaf, so it's optimizations should not be shown.
-  await checkFrame(1);
+  yield checkFrame(1);
 
   // gRawSite2 and gRawSite3 are both optimizations on B, so they'll have
   // indices in descending order of # of samples.
-  await checkFrame(2, true);
+  yield checkFrame(2, true);
 
   // Leaf node (C) with no optimizations should not display any opts.
-  await checkFrame(3);
+  yield checkFrame(3);
 
   // Select the node with optimizations and change to a new recording
   // to ensure the opts view is cleared
   let rendered = once(JsCallTreeView, "focus");
   mousedown(window, $$(".call-tree-item")[2]);
-  await rendered;
+  yield rendered;
   let isHidden = $("#jit-optimizations-view").classList.contains("hidden");
   ok(!isHidden, "opts view should be visible when selecting a frame with opts");
 
   let select = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   setSelectedRecording(panel, 0);
-  await Promise.all([select, rendered]);
+  yield Promise.all([select, rendered]);
 
   isHidden = $("#jit-optimizations-view").classList.contains("hidden");
   ok(isHidden, "opts view is hidden when switching recordings");
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   setSelectedRecording(panel, 1);
-  await rendered;
+  yield rendered;
 
   rendered = once(JsCallTreeView, "focus");
   mousedown(window, $$(".call-tree-item")[2]);
-  await rendered;
+  yield rendered;
   isHidden = $("#jit-optimizations-view").classList.contains("hidden");
   ok(!isHidden, "opts view should be visible when selecting a frame with opts");
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(JIT_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "call tree rerendered when JIT pref changes");
   isHidden = $("#jit-optimizations-view").classList.contains("hidden");
   ok(isHidden, "opts view hidden when toggling off jit pref");
 
   rendered = once(JsCallTreeView, "focus");
   mousedown(window, $$(".call-tree-item")[2]);
-  await rendered;
+  yield rendered;
   isHidden = $("#jit-optimizations-view").classList.contains("hidden");
   ok(isHidden, "opts view hidden when jit pref off and selecting a frame with opts");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 
-  async function injectAndRenderProfilerData() {
+  function* injectAndRenderProfilerData() {
     // Get current recording and inject our mock data
     info("Injecting mock profile data");
     let recording = PerformanceController.getCurrentRecording();
@@ -99,15 +99,15 @@ async function spawnTest() {
     // Force a rerender
     let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
     JsCallTreeView.render(OverviewView.getTimeInterval());
-    await rendered;
+    yield rendered;
   }
 
-  async function checkFrame(frameIndex, hasOpts) {
+  function* checkFrame(frameIndex, hasOpts) {
     info(`Checking frame ${frameIndex}`);
     // Click the frame
     let rendered = once(JsCallTreeView, "focus");
     mousedown(window, $$(".call-tree-item")[frameIndex]);
-    await rendered;
+    yield rendered;
 
     let isHidden = $("#jit-optimizations-view").classList.contains("hidden");
     if (hasOpts) {
diff --git a/devtools/client/performance/test/browser_perf-options-show-platform-data-01.js b/devtools/client/performance/test/browser_perf-options-show-platform-data-01.js
index 0186ce82579c..20e69bd9a83f 100644
--- a/devtools/client/performance/test/browser_perf-options-show-platform-data-01.js
+++ b/devtools/client/performance/test/browser_perf-options-show-platform-data-01.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,22 +22,22 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "JsCallTreeView rerendered when toggling show-idle-blocks.");
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "JsCallTreeView rerendered when toggling back show-idle-blocks.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-options-show-platform-data-02.js b/devtools/client/performance/test/browser_perf-options-show-platform-data-02.js
index 8044561f81c6..df199e797c4b 100644
--- a/devtools/client/performance/test/browser_perf-options-show-platform-data-02.js
+++ b/devtools/client/performance/test/browser_perf-options-show-platform-data-02.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,22 +22,22 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield rendered;
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, false);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling show-idle-blocks.");
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   Services.prefs.setBoolPref(UI_SHOW_PLATFORM_DATA_PREF, true);
-  await rendered;
+  yield rendered;
   ok(true, "JsFlameGraphView rerendered when toggling back show-idle-blocks.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-render-01.js b/devtools/client/performance/test/browser_perf-overview-render-01.js
index ea4d2b420a8b..a34ba21eaf02 100644
--- a/devtools/client/performance/test/browser_perf-overview-render-01.js
+++ b/devtools/client/performance/test/browser_perf-overview-render-01.js
@@ -12,23 +12,23 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, OverviewView } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   // Ensure overview keeps rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
   ok(true, "Overview was rendered while recording.");
 
-  await stopRecording(panel);
-  await teardownToolboxAndRemoveTab(panel);
+  yield stopRecording(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-render-02.js b/devtools/client/performance/test/browser_perf-overview-render-02.js
index 7f2442f6e187..a7cb7026ebf7 100644
--- a/devtools/client/performance/test/browser_perf-overview-render-02.js
+++ b/devtools/client/performance/test/browser_perf-overview-render-02.js
@@ -14,8 +14,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -25,7 +25,7 @@ add_task(async function () {
   // Enable memory to test.
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, true);
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   let framerate = OverviewView.graphs.get("framerate");
   let markers = OverviewView.graphs.get("timeline");
@@ -53,7 +53,7 @@ add_task(async function () {
     "The memory overview shouldn't have a selection before recording.");
 
   // Ensure overview keeps rendering.
-  await times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
+  yield times(OverviewView, EVENTS.UI_OVERVIEW_RENDERED, 3, {
     expectedArgs: { "1": Constants.FRAMERATE_GRAPH_LOW_RES_INTERVAL }
   });
 
@@ -78,7 +78,7 @@ add_task(async function () {
   is(memory.hasSelection(), false,
     "The memory overview still shouldn't have a selection before recording.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(framerate.selectionEnabled, true,
     "The selection should now be enabled for the framerate overview.");
@@ -87,5 +87,5 @@ add_task(async function () {
   is(memory.selectionEnabled, true,
     "The selection should now be enabled for the memory overview.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-render-03.js b/devtools/client/performance/test/browser_perf-overview-render-03.js
index 8d8399f6ad7c..e46ce2f91b1f 100644
--- a/devtools/client/performance/test/browser_perf-overview-render-03.js
+++ b/devtools/client/performance/test/browser_perf-overview-render-03.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -61,16 +61,16 @@ add_task(async function () {
       "The markers and framerate graphs data scale are the same.");
   };
 
-  await startRecording(panel);
+  yield startRecording(panel);
   doChecks();
 
-  await waitUntil(() => PerformanceController.getCurrentRecording().getMarkers().length);
-  await waitUntil(() => PerformanceController.getCurrentRecording().getMemory().length);
-  await waitUntil(() => PerformanceController.getCurrentRecording().getTicks().length);
+  yield waitUntil(() => PerformanceController.getCurrentRecording().getMarkers().length);
+  yield waitUntil(() => PerformanceController.getCurrentRecording().getMemory().length);
+  yield waitUntil(() => PerformanceController.getCurrentRecording().getTicks().length);
   doChecks();
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   doChecks();
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-render-04.js b/devtools/client/performance/test/browser_perf-overview-render-04.js
index 65d3f7967c21..22c8568511b8 100644
--- a/devtools/client/performance/test/browser_perf-overview-render-04.js
+++ b/devtools/client/performance/test/browser_perf-overview-render-04.js
@@ -15,8 +15,8 @@ const { waitUntil } = require("devtools/client/performance/test/helpers/wait-uti
 const { isVisible } = require("devtools/client/performance/test/helpers/dom-utils");
 const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -32,23 +32,23 @@ add_task(async function () {
   let updated = 0;
   OverviewView.on(EVENTS.UI_OVERVIEW_RENDERED, () => updated++);
 
-  await startRecording(panel, { skipWaitingForOverview: true });
+  yield startRecording(panel, { skipWaitingForOverview: true });
 
   is(isVisible($("#overview-pane")), false, "Overview graphs hidden.");
   is(updated, 0, "Overview graphs have not been updated");
 
-  await waitUntil(() => PerformanceController.getCurrentRecording().getMarkers().length);
-  await waitUntil(() => PerformanceController.getCurrentRecording().getMemory().length);
-  await waitUntil(() => PerformanceController.getCurrentRecording().getTicks().length);
+  yield waitUntil(() => PerformanceController.getCurrentRecording().getMarkers().length);
+  yield waitUntil(() => PerformanceController.getCurrentRecording().getMemory().length);
+  yield waitUntil(() => PerformanceController.getCurrentRecording().getTicks().length);
   is(isVisible($("#overview-pane")), false, "Overview graphs still hidden.");
   is(updated, 0, "Overview graphs have still not been updated");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(isVisible($("#overview-pane")), true, "Overview graphs no longer hidden.");
   is(updated, 1, "Overview graphs rendered upon completion.");
 
-  await startRecording(panel, { skipWaitingForOverview: true });
+  yield startRecording(panel, { skipWaitingForOverview: true });
 
   is(isVisible($("#overview-pane")), false,
      "Overview graphs hidden again when starting new recording.");
@@ -64,11 +64,11 @@ add_task(async function () {
      "Overview graphs hidden again when going back to inprogress recording.");
   is(updated, 1, "Overview graphs have not been updated again.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(isVisible($("#overview-pane")), true,
      "overview graphs no longer hidden when recording finishes");
   is(updated, 2, "Overview graphs rendered again upon completion.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-selection-01.js b/devtools/client/performance/test/browser_perf-overview-selection-01.js
index b7e0c130bff4..b8a8d730bfae 100644
--- a/devtools/client/performance/test/browser_perf-overview-selection-01.js
+++ b/devtools/client/performance/test/browser_perf-overview-selection-01.js
@@ -12,16 +12,16 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { dragStartCanvasGraph, dragStopCanvasGraph, clickCanvasGraph } = require("devtools/client/performance/test/helpers/input-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, PerformanceController, OverviewView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let duration = PerformanceController.getCurrentRecording().getDuration();
   let graph = OverviewView.graphs.get("timeline");
@@ -31,13 +31,13 @@ add_task(async function () {
   let rangeSelected = once(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED,
                            { spreadArgs: true });
   dragStartCanvasGraph(graph, { x: 0 });
-  let [, { startTime, endTime }] = await rangeSelected;
+  let [, { startTime, endTime }] = yield rangeSelected;
   is(endTime, duration, "The selected range is the entire graph, for now.");
 
   rangeSelected = once(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED,
                        { spreadArgs: true });
   dragStopCanvasGraph(graph, { x: graph.width / 2 });
-  [, { startTime, endTime }] = await rangeSelected;
+  [, { startTime, endTime }] = yield rangeSelected;
   is(endTime, duration / 2, "The selected range is half of the graph.");
 
   is(graph.hasSelection(), true,
@@ -58,7 +58,7 @@ add_task(async function () {
   rangeSelected = once(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED,
                        { spreadArgs: true });
   clickCanvasGraph(graph, { x: 3 * graph.width / 4 });
-  [, { startTime, endTime }] = await rangeSelected;
+  [, { startTime, endTime }] = yield rangeSelected;
 
   is(graph.hasSelection(), false,
     "A selection no longer on the graph.");
@@ -67,5 +67,5 @@ add_task(async function () {
   is(endTime, duration,
     "The UI_OVERVIEW_RANGE_SELECTED event fired with duration as `endTime`.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-selection-02.js b/devtools/client/performance/test/browser_perf-overview-selection-02.js
index 3f0dccea6f8a..71b410094664 100644
--- a/devtools/client/performance/test/browser_perf-overview-selection-02.js
+++ b/devtools/client/performance/test/browser_perf-overview-selection-02.js
@@ -11,8 +11,8 @@ const { UI_ENABLE_MEMORY_PREF } = require("devtools/client/performance/test/help
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -22,7 +22,7 @@ add_task(async function () {
   // Enable memory to test.
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, true);
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   let markersOverview = OverviewView.graphs.get("timeline");
   let memoryGraph = OverviewView.graphs.get("memory");
@@ -42,7 +42,7 @@ add_task(async function () {
   ok(!framerateGraph.selectionEnabled,
     "Selection shouldn't be enabled when the first recording started (1).");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   ok(markersOverview.selectionEnabled,
     "Selection should be enabled when the first recording finishes (2).");
@@ -51,7 +51,7 @@ add_task(async function () {
   ok(framerateGraph.selectionEnabled,
     "Selection should be enabled when the first recording finishes (1).");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   ok(!markersOverview.selectionEnabled,
     "Selection shouldn't be enabled when the second recording started (2).");
@@ -60,7 +60,7 @@ add_task(async function () {
   ok(!framerateGraph.selectionEnabled,
     "Selection shouldn't be enabled when the second recording started (1).");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   ok(markersOverview.selectionEnabled,
     "Selection should be enabled when the first second finishes (2).");
@@ -69,5 +69,5 @@ add_task(async function () {
   ok(framerateGraph.selectionEnabled,
     "Selection should be enabled when the first second finishes (1).");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-selection-03.js b/devtools/client/performance/test/browser_perf-overview-selection-03.js
index 9e9493609e90..8f06901e8f4d 100644
--- a/devtools/client/performance/test/browser_perf-overview-selection-03.js
+++ b/devtools/client/performance/test/browser_perf-overview-selection-03.js
@@ -13,8 +13,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { times } = require("devtools/client/performance/test/helpers/event-utils");
 const { dragStartCanvasGraph, dragStopCanvasGraph } = require("devtools/client/performance/test/helpers/input-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -24,8 +24,8 @@ add_task(async function () {
   // Enable memory to test.
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let markersOverview = OverviewView.graphs.get("timeline");
   let memoryGraph = OverviewView.graphs.get("memory");
@@ -37,7 +37,7 @@ add_task(async function () {
   let rangeSelected = times(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED, 2);
   dragStartCanvasGraph(framerateGraph, { x: 0 });
   dragStopCanvasGraph(framerateGraph, { x: width / 2 });
-  await rangeSelected;
+  yield rangeSelected;
 
   is(markersOverview.getSelection().toSource(), framerateGraph.getSelection().toSource(),
     "The markers overview has a correct selection.");
@@ -53,7 +53,7 @@ add_task(async function () {
   rangeSelected = times(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED, 2);
   dragStartCanvasGraph(markersOverview, { x: 0 });
   dragStopCanvasGraph(markersOverview, { x: width / 4 });
-  await rangeSelected;
+  yield rangeSelected;
 
   is(markersOverview.getSelection().toSource(), framerateGraph.getSelection().toSource(),
     "The markers overview has a correct selection.");
@@ -69,7 +69,7 @@ add_task(async function () {
   rangeSelected = times(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED, 2);
   dragStartCanvasGraph(memoryGraph, { x: 0 });
   dragStopCanvasGraph(memoryGraph, { x: width / 10 });
-  await rangeSelected;
+  yield rangeSelected;
 
   is(markersOverview.getSelection().toSource(), framerateGraph.getSelection().toSource(),
     "The markers overview has a correct selection.");
@@ -78,5 +78,5 @@ add_task(async function () {
   is(framerateGraph.getSelection().toSource(), "({start:0, end:" + (width / 10) + "})",
     "The framerate graph has a correct selection.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-overview-time-interval.js b/devtools/client/performance/test/browser_perf-overview-time-interval.js
index c7c13e9b7c6b..b66e3ef86097 100644
--- a/devtools/client/performance/test/browser_perf-overview-time-interval.js
+++ b/devtools/client/performance/test/browser_perf-overview-time-interval.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -34,14 +34,14 @@ add_task(async function () {
     ok(true, "Getting the time interval didn't work, as expected.");
   }
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   // Get/set the time interval and wait for the event propagation.
 
   let rangeSelected = once(OverviewView, EVENTS.UI_OVERVIEW_RANGE_SELECTED);
   OverviewView.setTimeInterval({ startTime: 10, endTime: 20 });
-  await rangeSelected;
+  yield rangeSelected;
 
   let firstInterval = OverviewView.getTimeInterval();
   info("First interval start time: " + firstInterval.startTime);
@@ -69,5 +69,5 @@ add_task(async function () {
   is(Math.round(secondInterval.endTime), 40,
     "The interval's end time was properly set again.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-private-browsing.js b/devtools/client/performance/test/browser_perf-private-browsing.js
index b4f39b3f06af..dd2383fd4da5 100644
--- a/devtools/client/performance/test/browser_perf-private-browsing.js
+++ b/devtools/client/performance/test/browser_perf-private-browsing.js
@@ -14,25 +14,25 @@ const { once } = require("devtools/client/performance/test/helpers/event-utils")
 
 let gPanelWinTuples = [];
 
-add_task(async function () {
-  await testNormalWindow();
-  await testPrivateWindow();
-  await testRecordingFailingInWindow(0);
-  await testRecordingFailingInWindow(1);
-  await teardownPerfInWindow(1, { shouldCloseWindow: true, dontWaitForTabClose: true });
-  await testRecordingSucceedingInWindow(0);
-  await teardownPerfInWindow(0, { shouldCloseWindow: false });
+add_task(function* () {
+  yield testNormalWindow();
+  yield testPrivateWindow();
+  yield testRecordingFailingInWindow(0);
+  yield testRecordingFailingInWindow(1);
+  yield teardownPerfInWindow(1, { shouldCloseWindow: true, dontWaitForTabClose: true });
+  yield testRecordingSucceedingInWindow(0);
+  yield teardownPerfInWindow(0, { shouldCloseWindow: false });
 
   gPanelWinTuples = null;
 });
 
-async function createPanelInNewWindow(options) {
-  let win = await addWindow(options);
-  return createPanelInWindow(options, win);
+function* createPanelInNewWindow(options) {
+  let win = yield addWindow(options);
+  return yield createPanelInWindow(options, win);
 }
 
-async function createPanelInWindow(options, win = window) {
-  let { panel } = await initPerformanceInNewTab({
+function* createPanelInWindow(options, win = window) {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: win
   }, options);
@@ -41,8 +41,8 @@ async function createPanelInWindow(options, win = window) {
   return { panel, win };
 }
 
-async function testNormalWindow() {
-  let { panel } = await createPanelInWindow({
+function* testNormalWindow() {
+  let { panel } = yield createPanelInWindow({
     private: false
   });
 
@@ -52,8 +52,8 @@ async function testNormalWindow() {
     "The initial state of the performance panel view is correct (1).");
 }
 
-async function testPrivateWindow() {
-  let { panel } = await createPanelInNewWindow({
+function* testPrivateWindow() {
+  let { panel } = yield createPanelInNewWindow({
     private: true,
     // The add-on SDK can't seem to be able to listen to "ready" or "close"
     // events for private tabs. Don't really absolutely need to though.
@@ -66,7 +66,7 @@ async function testPrivateWindow() {
     "The initial state of the performance panel view is correct (2).");
 }
 
-async function testRecordingFailingInWindow(index) {
+function* testRecordingFailingInWindow(index) {
   let { panel } = gPanelWinTuples[index];
   let { EVENTS, PerformanceController } = panel.panelWin;
 
@@ -79,13 +79,13 @@ async function testRecordingFailingInWindow(index) {
   let whenFailed = once(PerformanceController,
                         EVENTS.BACKEND_FAILED_AFTER_RECORDING_START);
   PerformanceController.startRecording();
-  await whenFailed;
+  yield whenFailed;
   ok(true, "Recording has failed.");
 
   PerformanceController.off(EVENTS.RECORDING_STATE_CHANGE, onRecordingStarted);
 }
 
-async function testRecordingSucceedingInWindow(index) {
+function* testRecordingSucceedingInWindow(index) {
   let { panel } = gPanelWinTuples[index];
   let { EVENTS, PerformanceController } = panel.panelWin;
 
@@ -96,17 +96,17 @@ async function testRecordingSucceedingInWindow(index) {
   PerformanceController.on(EVENTS.BACKEND_FAILED_AFTER_RECORDING_START,
                            onRecordingFailed);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has succeeded.");
 
   PerformanceController.off(EVENTS.BACKEND_FAILED_AFTER_RECORDING_START,
                            onRecordingFailed);
 }
 
-async function teardownPerfInWindow(index, options) {
+function* teardownPerfInWindow(index, options) {
   let { panel, win } = gPanelWinTuples[index];
-  await teardownToolboxAndRemoveTab(panel, options);
+  yield teardownToolboxAndRemoveTab(panel, options);
 
   if (options.shouldCloseWindow) {
     win.close();
diff --git a/devtools/client/performance/test/browser_perf-range-changed-render.js b/devtools/client/performance/test/browser_perf-range-changed-render.js
index ec3ecf208092..b3b9c6a92a4f 100644
--- a/devtools/client/performance/test/browser_perf-range-changed-render.js
+++ b/devtools/client/performance/test/browser_perf-range-changed-render.js
@@ -11,8 +11,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -36,37 +36,37 @@ add_task(async function () {
   JsCallTreeView.on(EVENTS.UI_JS_CALL_TREE_RENDERED, updateCallTree);
   JsFlameGraphView.on(EVENTS.UI_JS_FLAMEGRAPH_RENDERED, updateFlameGraph);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.emit(EVENTS.UI_OVERVIEW_RANGE_SELECTED, { startTime: 0, endTime: 10 });
-  await rendered;
+  yield rendered;
   ok(true, "Waterfall rerenders when a range in the overview graph is selected.");
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
   ok(true, "Call tree rerenders after its corresponding pane is shown.");
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
-  await DetailsView.selectView("js-flamegraph");
-  await rendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield rendered;
   ok(true, "Flamegraph rerenders after its corresponding pane is shown.");
 
   rendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
   OverviewView.emit(EVENTS.UI_OVERVIEW_RANGE_SELECTED);
-  await rendered;
+  yield rendered;
   ok(true, "Flamegraph rerenders when a range in the overview graph is removed.");
 
   rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
-  await DetailsView.selectView("js-calltree");
-  await rendered;
+  yield DetailsView.selectView("js-calltree");
+  yield rendered;
   ok(true, "Call tree rerenders after its corresponding pane is shown.");
 
   rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
-  await DetailsView.selectView("waterfall");
-  await rendered;
+  yield DetailsView.selectView("waterfall");
+  yield rendered;
   ok(true, "Waterfall rerenders after its corresponding pane is shown.");
 
   is(updatedWaterfall, 3, "WaterfallView rerendered 3 times.");
@@ -77,5 +77,5 @@ add_task(async function () {
   JsCallTreeView.off(EVENTS.UI_JS_CALL_TREE_RENDERED, updateCallTree);
   JsFlameGraphView.off(EVENTS.UI_JS_FLAMEGRAPH_RENDERED, updateFlameGraph);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-notices-01.js b/devtools/client/performance/test/browser_perf-recording-notices-01.js
index 931b07bc887e..697691a558ba 100644
--- a/devtools/client/performance/test/browser_perf-recording-notices-01.js
+++ b/devtools/client/performance/test/browser_perf-recording-notices-01.js
@@ -11,8 +11,8 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -29,17 +29,17 @@ add_task(async function () {
   is(PerformanceView.getState(), "empty", "Correct default state.");
   is(MAIN_CONTAINER.selectedPanel, EMPTY, "Showing empty panel on load.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(PerformanceView.getState(), "recording", "Correct state during recording.");
   is(MAIN_CONTAINER.selectedPanel, CONTENT, "Showing main view with timeline.");
   is(DETAILS_CONTAINER.selectedPanel, RECORDING, "Showing recording panel.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceView.getState(), "recorded", "Correct state after recording.");
   is(MAIN_CONTAINER.selectedPanel, CONTENT, "Showing main view with timeline.");
   is(DETAILS_CONTAINER.selectedPanel, DETAILS, "Showing rendered graphs.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-notices-02.js b/devtools/client/performance/test/browser_perf-recording-notices-02.js
index 0c81f5f397bb..b7905b3d7100 100644
--- a/devtools/client/performance/test/browser_perf-recording-notices-02.js
+++ b/devtools/client/performance/test/browser_perf-recording-notices-02.js
@@ -13,8 +13,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -32,10 +32,10 @@ add_task(async function () {
   let RECORDING = $("#recording-notice");
   let DETAILS = $("#details-pane");
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(PerformanceView.getState(), "recording", "Correct state during recording.");
   is(MAIN_CONTAINER.selectedPanel, CONTENT, "Showing main view with timeline.");
@@ -43,7 +43,7 @@ add_task(async function () {
 
   let selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await selected;
+  yield selected;
 
   is(PerformanceView.getState(), "recorded",
      "Correct state during recording but selecting a completed recording.");
@@ -52,14 +52,14 @@ add_task(async function () {
 
   selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 1);
-  await selected;
+  yield selected;
 
   is(PerformanceView.getState(), "recording",
      "Correct state when switching back to recording in progress.");
   is(MAIN_CONTAINER.selectedPanel, CONTENT, "Showing main view with timeline.");
   is(DETAILS_CONTAINER.selectedPanel, RECORDING, "Showing recording panel.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-notices-03.js b/devtools/client/performance/test/browser_perf-recording-notices-03.js
index d2add0df33dd..cb3779d10391 100644
--- a/devtools/client/performance/test/browser_perf-recording-notices-03.js
+++ b/devtools/client/performance/test/browser_perf-recording-notices-03.js
@@ -17,20 +17,20 @@ const { waitUntil } = require("devtools/client/performance/test/helpers/wait-uti
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
+add_task(function* () {
   // Make sure the profiler module is stopped so we can set a new buffer limit.
   pmmLoadFrameScripts(gBrowser);
-  await pmmStopProfiler();
+  yield pmmStopProfiler();
 
   // Keep the profiler's buffer large, but still get to 1% relatively quick.
   Services.prefs.setIntPref(PROFILER_BUFFER_SIZE_PREF, 1000000);
 
-  let { target, console } = await initConsoleInNewTab({
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let {
     gFront,
     EVENTS,
@@ -40,7 +40,7 @@ add_task(async function () {
   } = panel.panelWin;
 
   // Set a fast profiler-status update interval.
-  await gFront.setProfilerStatusInterval(10);
+  yield gFront.setProfilerStatusInterval(10);
 
   let DETAILS_CONTAINER = $("#details-pane-container");
   let NORMAL_BUFFER_STATUS_MESSAGE = $("#recording-notice .buffer-status-message");
@@ -49,10 +49,10 @@ add_task(async function () {
   let gPercent;
 
   // Start a manual recording.
-  await startRecording(panel);
+  yield startRecording(panel);
 
-  await waitUntil(async function () {
-    [, gPercent] = await once(PerformanceView,
+  yield waitUntil(function* () {
+    [, gPercent] = yield once(PerformanceView,
                               EVENTS.UI_RECORDING_PROFILER_STATUS_RENDERED,
                               { spreadArgs: true });
     return gPercent > 0;
@@ -68,10 +68,10 @@ add_task(async function () {
     "Buffer status text has correct percentage.");
 
   // Start a console profile.
-  await console.profile("rust");
+  yield console.profile("rust");
 
-  await waitUntil(async function () {
-    [, gPercent] = await once(PerformanceView,
+  yield waitUntil(function* () {
+    [, gPercent] = yield once(PerformanceView,
                               EVENTS.UI_RECORDING_PROFILER_STATUS_RENDERED,
                               { spreadArgs: true });
     return gPercent > Math.floor(bufferUsage * 100);
@@ -89,10 +89,10 @@ add_task(async function () {
   // Select the console recording.
   let selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 1);
-  await selected;
+  yield selected;
 
-  await waitUntil(async function () {
-    [, gPercent] = await once(PerformanceView,
+  yield waitUntil(function* () {
+    [, gPercent] = yield once(PerformanceView,
                               EVENTS.UI_RECORDING_PROFILER_STATUS_RENDERED,
                               { spreadArgs: true });
     return gPercent > 0;
@@ -106,14 +106,14 @@ add_task(async function () {
     "Buffer status text has correct percentage for console recording.");
 
   // Stop the console profile, then select the original manual recording.
-  await console.profileEnd("rust");
+  yield console.profileEnd("rust");
 
   selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await selected;
+  yield selected;
 
-  await waitUntil(async function () {
-    [, gPercent] = await once(PerformanceView,
+  yield waitUntil(function* () {
+    [, gPercent] = yield once(PerformanceView,
                               EVENTS.UI_RECORDING_PROFILER_STATUS_RENDERED,
                               { spreadArgs: true });
     return gPercent > Math.floor(bufferUsage * 100);
@@ -127,9 +127,9 @@ add_task(async function () {
     "Buffer status text has correct percentage.");
 
   // Stop the manual recording.
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 
   pmmClearFrameScripts();
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-notices-04.js b/devtools/client/performance/test/browser_perf-recording-notices-04.js
index 40b85843026b..61441e5d3389 100644
--- a/devtools/client/performance/test/browser_perf-recording-notices-04.js
+++ b/devtools/client/performance/test/browser_perf-recording-notices-04.js
@@ -15,15 +15,15 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
+add_task(function* () {
   // Make sure the profiler module is stopped so we can set a new buffer limit.
   pmmLoadFrameScripts(gBrowser);
-  await pmmStopProfiler();
+  yield pmmStopProfiler();
 
   // Keep the profiler's buffer small, to get to 100% really quickly.
   Services.prefs.setIntPref(PROFILER_BUFFER_SIZE_PREF, 10000);
 
-  let { panel } = await initPerformanceInNewTab({
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -31,17 +31,17 @@ add_task(async function () {
   let { gFront, EVENTS, $, PerformanceController, PerformanceView } = panel.panelWin;
 
   // Set a fast profiler-status update interval
-  await gFront.setProfilerStatusInterval(10);
+  yield gFront.setProfilerStatusInterval(10);
 
   let DETAILS_CONTAINER = $("#details-pane-container");
   let NORMAL_BUFFER_STATUS_MESSAGE = $("#recording-notice .buffer-status-message");
   let gPercent;
 
   // Start a manual recording.
-  await startRecording(panel);
+  yield startRecording(panel);
 
-  await waitUntil(async function () {
-    [, gPercent] = await once(PerformanceView,
+  yield waitUntil(function* () {
+    [, gPercent] = yield once(PerformanceView,
                               EVENTS.UI_RECORDING_PROFILER_STATUS_RENDERED,
                               { spreadArgs: true });
     return gPercent == 100;
@@ -58,9 +58,9 @@ add_task(async function () {
     "Buffer status text has correct percentage.");
 
   // Stop the manual recording.
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 
   pmmClearFrameScripts();
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-notices-05.js b/devtools/client/performance/test/browser_perf-recording-notices-05.js
index 20546f106009..5107f81a6bad 100644
--- a/devtools/client/performance/test/browser_perf-recording-notices-05.js
+++ b/devtools/client/performance/test/browser_perf-recording-notices-05.js
@@ -9,8 +9,8 @@
 const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -18,7 +18,7 @@ add_task(async function () {
   let { gFront, $, PerformanceController } = panel.panelWin;
 
   // Set a fast profiler-status update interval
-  await gFront.setProfilerStatusInterval(10);
+  yield gFront.setProfilerStatusInterval(10);
 
   let enabled = false;
 
@@ -36,5 +36,5 @@ add_task(async function () {
   ok($("#performance-view").getAttribute("e10s"), "",
     "When e10s is enabled, there should be no e10s attribute.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-selected-01.js b/devtools/client/performance/test/browser_perf-recording-selected-01.js
index d7f4d932f80f..15cb66ec954e 100644
--- a/devtools/client/performance/test/browser_perf-recording-selected-01.js
+++ b/devtools/client/performance/test/browser_perf-recording-selected-01.js
@@ -13,19 +13,19 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { setSelectedRecording, getRecordingsCount, getSelectedRecordingIndex } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(getRecordingsCount(panel), 2,
     "There should be two recordings visible.");
@@ -34,12 +34,12 @@ add_task(async function () {
 
   let selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await selected;
+  yield selected;
 
   is(getRecordingsCount(panel), 2,
     "There should still be two recordings visible.");
   is(getSelectedRecordingIndex(panel), 0,
     "The first recording item should be selected.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-selected-02.js b/devtools/client/performance/test/browser_perf-recording-selected-02.js
index 0e202be613e2..0bffa3a73aa1 100644
--- a/devtools/client/performance/test/browser_perf-recording-selected-02.js
+++ b/devtools/client/performance/test/browser_perf-recording-selected-02.js
@@ -13,21 +13,21 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { getSelectedRecordingIndex, setSelectedRecording, getRecordingsCount } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
+add_task(function* () {
   // This test seems to take a very long time to finish on Linux VMs.
   requestLongerTimeout(4);
 
-  let { panel } = await initPerformanceInNewTab({
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { EVENTS, PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(getRecordingsCount(panel), 2,
     "There should be two recordings visible.");
@@ -36,7 +36,7 @@ add_task(async function () {
 
   let selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await selected;
+  yield selected;
 
   is(getRecordingsCount(panel), 2,
     "There should still be two recordings visible.");
@@ -45,14 +45,14 @@ add_task(async function () {
 
   selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 1);
-  await selected;
+  yield selected;
 
   is(getRecordingsCount(panel), 2,
     "There should still be two recordings visible.");
   is(getSelectedRecordingIndex(panel), 1,
     "The second recording item should be selected again.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-selected-03.js b/devtools/client/performance/test/browser_perf-recording-selected-03.js
index c1b1349a2073..7febfbb2b96d 100644
--- a/devtools/client/performance/test/browser_perf-recording-selected-03.js
+++ b/devtools/client/performance/test/browser_perf-recording-selected-03.js
@@ -14,31 +14,31 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { $, EVENTS, PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   info("Selecting recording #0 and waiting for it to be displayed.");
 
   let selected = once(PerformanceController, EVENTS.RECORDING_SELECTED);
   setSelectedRecording(panel, 0);
-  await selected;
+  yield selected;
 
   ok($("#main-record-button").classList.contains("checked"),
     "Button is still checked after selecting another item.");
   ok(!$("#main-record-button").hasAttribute("disabled"),
     "Button is not locked after selecting another item.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recording-selected-04.js b/devtools/client/performance/test/browser_perf-recording-selected-04.js
index d39149fcf7f5..014ef5bddb2b 100644
--- a/devtools/client/performance/test/browser_perf-recording-selected-04.js
+++ b/devtools/client/performance/test/browser_perf-recording-selected-04.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording, waitForAllWidgetsRendered } = require("devtools/client/performance/test/helpers/actions");
 const { setSelectedRecording } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -26,8 +26,8 @@ add_task(async function () {
   // Enable allocations to test the memory-calltree and memory-flamegraph.
   Services.prefs.setBoolPref(UI_ENABLE_ALLOCATIONS_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   // Ållow widgets to be updated while hidden, to make testing easier.
   DetailsSubview.canUpdateWhileHidden = true;
@@ -35,25 +35,25 @@ add_task(async function () {
   // Cycle through all the views to initialize them. The waterfall is shown
   // by default, but all the other views are created lazily, so won't emit
   // any events.
-  await DetailsView.selectView("js-calltree");
-  await DetailsView.selectView("js-flamegraph");
-  await DetailsView.selectView("memory-calltree");
-  await DetailsView.selectView("memory-flamegraph");
+  yield DetailsView.selectView("js-calltree");
+  yield DetailsView.selectView("js-flamegraph");
+  yield DetailsView.selectView("memory-calltree");
+  yield DetailsView.selectView("memory-flamegraph");
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let rerender = waitForAllWidgetsRendered(panel);
   setSelectedRecording(panel, 0);
-  await rerender;
+  yield rerender;
 
   ok(true, "All widgets were rendered when selecting the first recording.");
 
   rerender = waitForAllWidgetsRendered(panel);
   setSelectedRecording(panel, 1);
-  await rerender;
+  yield rerender;
 
   ok(true, "All widgets were rendered when selecting the second recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recordings-clear-01.js b/devtools/client/performance/test/browser_perf-recordings-clear-01.js
index 79722c0fc04a..87579896a273 100644
--- a/devtools/client/performance/test/browser_perf-recordings-clear-01.js
+++ b/devtools/client/performance/test/browser_perf-recordings-clear-01.js
@@ -12,8 +12,8 @@ const { initPanelInNewTab, teardownToolboxAndRemoveTab } = require("devtools/cli
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { getRecordingsCount } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPanelInNewTab({
+add_task(function* () {
+  let { panel } = yield initPanelInNewTab({
     tool: "performance",
     url: SIMPLE_URL,
     win: window
@@ -21,8 +21,8 @@ add_task(async function () {
 
   let { PerformanceController, PerformanceView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(getRecordingsCount(panel), 1,
     "The recordings list should have one recording.");
@@ -31,8 +31,8 @@ add_task(async function () {
   isnot(PerformanceController.getCurrentRecording(), null,
     "There should be a current recording.");
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(getRecordingsCount(panel), 2,
     "The recordings list should have two recordings.");
@@ -41,7 +41,7 @@ add_task(async function () {
   isnot(PerformanceController.getCurrentRecording(), null,
     "There should be a current recording.");
 
-  await PerformanceController.clearRecordings();
+  yield PerformanceController.clearRecordings();
 
   is(getRecordingsCount(panel), 0,
     "The recordings list should be empty.");
@@ -50,5 +50,5 @@ add_task(async function () {
   is(PerformanceController.getCurrentRecording(), null,
     "There should be no current recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recordings-clear-02.js b/devtools/client/performance/test/browser_perf-recordings-clear-02.js
index f57f0409d046..d8196dbd1a79 100644
--- a/devtools/client/performance/test/browser_perf-recordings-clear-02.js
+++ b/devtools/client/performance/test/browser_perf-recordings-clear-02.js
@@ -13,8 +13,8 @@ const { startRecording, stopRecording } = require("devtools/client/performance/t
 const { times, once } = require("devtools/client/performance/test/helpers/event-utils");
 const { getRecordingsCount } = require("devtools/client/performance/test/helpers/recording-utils");
 
-add_task(async function () {
-  let { panel } = await initPanelInNewTab({
+add_task(function* () {
+  let { panel } = yield initPanelInNewTab({
     tool: "performance",
     url: SIMPLE_URL,
     win: window
@@ -22,8 +22,8 @@ add_task(async function () {
 
   let { EVENTS, PerformanceController, PerformanceView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(getRecordingsCount(panel), 1,
     "The recordings list should have one recording.");
@@ -32,7 +32,7 @@ add_task(async function () {
   isnot(PerformanceController.getCurrentRecording(), null,
     "There should be a current recording.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(getRecordingsCount(panel), 2,
     "The recordings list should have two recordings.");
@@ -48,8 +48,8 @@ add_task(async function () {
 
   PerformanceController.clearRecordings();
 
-  await recordingDeleted;
-  await recordingStopped;
+  yield recordingDeleted;
+  yield recordingStopped;
 
   is(getRecordingsCount(panel), 0,
     "The recordings list should be empty.");
@@ -59,11 +59,11 @@ add_task(async function () {
     "There should be no current recording.");
 
   // Bug 1169146: Try another recording after clearing mid-recording.
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(getRecordingsCount(panel), 1,
     "The recordings list should have one recording.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-recordings-io-01.js b/devtools/client/performance/test/browser_perf-recordings-io-01.js
index 63040566c199..90a0144215da 100644
--- a/devtools/client/performance/test/browser_perf-recordings-io-01.js
+++ b/devtools/client/performance/test/browser_perf-recordings-io-01.js
@@ -6,8 +6,8 @@
  * Tests if the performance tool is able to save and load recordings.
  */
 
-var test = async function () {
-  var { target, panel, toolbox } = await initPerformance(SIMPLE_URL);
+var test = Task.async(function* () {
+  var { target, panel, toolbox } = yield initPerformance(SIMPLE_URL);
   var { $, EVENTS, PerformanceController, PerformanceView, DetailsView, DetailsSubview } = panel.panelWin;
 
   // Enable allocations to test the memory-calltree and memory-flamegraph.
@@ -19,16 +19,16 @@ var test = async function () {
   // `waitForWidgetsRendered`.
   DetailsSubview.canUpdateWhileHidden = true;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   // Cycle through all the views to initialize them, otherwise we can't use
   // `waitForWidgetsRendered`. The waterfall is shown by default, but all the
   // other views are created lazily, so won't emit any events.
-  await DetailsView.selectView("js-calltree");
-  await DetailsView.selectView("js-flamegraph");
-  await DetailsView.selectView("memory-calltree");
-  await DetailsView.selectView("memory-flamegraph");
+  yield DetailsView.selectView("js-calltree");
+  yield DetailsView.selectView("js-flamegraph");
+  yield DetailsView.selectView("memory-calltree");
+  yield DetailsView.selectView("memory-flamegraph");
 
   // Verify original recording.
 
@@ -41,9 +41,9 @@ var test = async function () {
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
 
   let exported = once(PerformanceController, EVENTS.RECORDING_EXPORTED);
-  await PerformanceController.exportRecording("", PerformanceController.getCurrentRecording(), file);
+  yield PerformanceController.exportRecording("", PerformanceController.getCurrentRecording(), file);
 
-  await exported;
+  yield exported;
   ok(true, "The recording data appears to have been successfully saved.");
 
  //  Check if the imported file name has tmpprofile in it as the file
@@ -59,10 +59,10 @@ var test = async function () {
   let imported = once(PerformanceController, EVENTS.RECORDING_IMPORTED);
   PerformanceView.emit(EVENTS.UI_IMPORT_RECORDING, file);
 
-  await imported;
+  yield imported;
   ok(true, "The recording data appears to have been successfully imported.");
 
-  await rerendered;
+  yield rerendered;
   ok(true, "The imported data was re-rendered.");
 
   // Verify imported recording.
@@ -88,7 +88,7 @@ var test = async function () {
   is(importedData.configuration.withMemory, originalData.configuration.withMemory,
     "The imported data is identical to the original data (8).");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
-};
+});
 /* eslint-enable */
diff --git a/devtools/client/performance/test/browser_perf-recordings-io-02.js b/devtools/client/performance/test/browser_perf-recordings-io-02.js
index 3104a40e9685..48e7fb63c822 100644
--- a/devtools/client/performance/test/browser_perf-recordings-io-02.js
+++ b/devtools/client/performance/test/browser_perf-recordings-io-02.js
@@ -6,21 +6,21 @@
  * Tests if the performance tool gracefully handles loading bogus files.
  */
 
-var test = async function () {
-  let { target, panel, toolbox } = await initPerformance(SIMPLE_URL);
+var test = Task.async(function* () {
+  let { target, panel, toolbox } = yield initPerformance(SIMPLE_URL);
   let { EVENTS, PerformanceController } = panel.panelWin;
 
   let file = FileUtils.getFile("TmpD", ["tmpprofile.json"]);
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
 
   try {
-    await PerformanceController.importRecording("", file);
+    yield PerformanceController.importRecording("", file);
     ok(false, "The recording succeeded unexpectedly.");
   } catch (e) {
     is(e.message, "Could not read recording data file.", "Message is correct.");
     ok(true, "The recording was cancelled.");
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
-};
+});
diff --git a/devtools/client/performance/test/browser_perf-recordings-io-03.js b/devtools/client/performance/test/browser_perf-recordings-io-03.js
index 791f373c76e6..d53268c3e685 100644
--- a/devtools/client/performance/test/browser_perf-recordings-io-03.js
+++ b/devtools/client/performance/test/browser_perf-recordings-io-03.js
@@ -10,25 +10,25 @@
 var { FileUtils } = ChromeUtils.import("resource://gre/modules/FileUtils.jsm", {});
 var { NetUtil } = ChromeUtils.import("resource://gre/modules/NetUtil.jsm", {});
 
-var test = async function () {
-  let { target, panel, toolbox } = await initPerformance(SIMPLE_URL);
+var test = Task.async(function* () {
+  let { target, panel, toolbox } = yield initPerformance(SIMPLE_URL);
   let { EVENTS, PerformanceController } = panel.panelWin;
 
   let file = FileUtils.getFile("TmpD", ["tmpprofile.json"]);
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
-  await asyncCopy({ bogus: "data" }, file);
+  yield asyncCopy({ bogus: "data" }, file);
 
   try {
-    await PerformanceController.importRecording("", file);
+    yield PerformanceController.importRecording("", file);
     ok(false, "The recording succeeded unexpectedly.");
   } catch (e) {
     is(e.message, "Unrecognized recording data file.", "Message is correct.");
     ok(true, "The recording was cancelled.");
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
-};
+});
 
 function getUnicodeConverter() {
   let className = "@mozilla.org/intl/scriptableunicodeconverter";
diff --git a/devtools/client/performance/test/browser_perf-recordings-io-04.js b/devtools/client/performance/test/browser_perf-recordings-io-04.js
index 8d7b5b7d0b89..8fff37c81b38 100644
--- a/devtools/client/performance/test/browser_perf-recordings-io-04.js
+++ b/devtools/client/performance/test/browser_perf-recordings-io-04.js
@@ -69,8 +69,8 @@ var PROFILER_DATA = (function () {
   return data;
 })();
 
-var test = async function () {
-  let { target, panel, toolbox } = await initPerformance(SIMPLE_URL);
+var test = Task.async(function* () {
+  let { target, panel, toolbox } = yield initPerformance(SIMPLE_URL);
   let { $, EVENTS, PerformanceController, DetailsView, OverviewView, JsCallTreeView } = panel.panelWin;
 
   // Enable memory to test the memory-calltree and memory-flamegraph.
@@ -90,20 +90,20 @@ var test = async function () {
   // Save recording as an old profiler data.
   let file = FileUtils.getFile("TmpD", ["tmpprofile.json"]);
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
-  await asyncCopy(oldProfilerData, file);
+  yield asyncCopy(oldProfilerData, file);
 
   // Import recording.
 
   let calltreeRendered = once(OverviewView, EVENTS.UI_FRAMERATE_GRAPH_RENDERED);
   let fpsRendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   let imported = once(PerformanceController, EVENTS.RECORDING_IMPORTED);
-  await PerformanceController.importRecording("", file);
+  yield PerformanceController.importRecording("", file);
 
-  await imported;
+  yield imported;
   ok(true, "The original profiler data appears to have been successfully imported.");
 
-  await calltreeRendered;
-  await fpsRendered;
+  yield calltreeRendered;
+  yield fpsRendered;
   ok(true, "The imported data was re-rendered.");
 
   // Ensure that only framerate and js calltree/flamegraph view are available
@@ -148,9 +148,9 @@ var test = async function () {
     }
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
-};
+});
 
 function getUnicodeConverter() {
   let className = "@mozilla.org/intl/scriptableunicodeconverter";
diff --git a/devtools/client/performance/test/browser_perf-recordings-io-05.js b/devtools/client/performance/test/browser_perf-recordings-io-05.js
index 4d671543d20b..e836da917fda 100644
--- a/devtools/client/performance/test/browser_perf-recordings-io-05.js
+++ b/devtools/client/performance/test/browser_perf-recordings-io-05.js
@@ -7,12 +7,12 @@
  * `getMappedSelection` error.
  */
 
-var test = async function () {
-  var { target, panel, toolbox } = await initPerformance(SIMPLE_URL);
+var test = Task.async(function* () {
+  var { target, panel, toolbox } = yield initPerformance(SIMPLE_URL);
   var { EVENTS, PerformanceController, WaterfallView } = panel.panelWin;
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   // Save recording.
 
@@ -20,24 +20,24 @@ var test = async function () {
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
 
   let exported = once(PerformanceController, EVENTS.RECORDING_EXPORTED);
-  await PerformanceController.exportRecording("", PerformanceController.getCurrentRecording(), file);
+  yield PerformanceController.exportRecording("", PerformanceController.getCurrentRecording(), file);
 
-  await exported;
+  yield exported;
   ok(true, "The recording data appears to have been successfully saved.");
 
   // Clear and re-import.
 
-  await PerformanceController.clearRecordings();
+  yield PerformanceController.clearRecordings();
 
   let rendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   let imported = once(PerformanceController, EVENTS.RECORDING_IMPORTED);
-  await PerformanceController.importRecording("", file);
-  await imported;
-  await rendered;
+  yield PerformanceController.importRecording("", file);
+  yield imported;
+  yield rendered;
 
   ok(true, "No error was thrown.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
-};
+});
 /* eslint-enable */
diff --git a/devtools/client/performance/test/browser_perf-recordings-io-06.js b/devtools/client/performance/test/browser_perf-recordings-io-06.js
index 8a52c38e4150..e3a40680bf90 100644
--- a/devtools/client/performance/test/browser_perf-recordings-io-06.js
+++ b/devtools/client/performance/test/browser_perf-recordings-io-06.js
@@ -84,8 +84,8 @@ var PROFILER_DATA = (function () {
   return data;
 })();
 
-var test = async function () {
-  let { target, panel, toolbox } = await initPerformance(SIMPLE_URL);
+var test = Task.async(function* () {
+  let { target, panel, toolbox } = yield initPerformance(SIMPLE_URL);
   let { $, EVENTS, PerformanceController, DetailsView, JsCallTreeView } = panel.panelWin;
 
   let profilerData = {
@@ -98,23 +98,23 @@ var test = async function () {
 
   let file = FileUtils.getFile("TmpD", ["tmpprofile.json"]);
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
-  await asyncCopy(profilerData, file);
+  yield asyncCopy(profilerData, file);
 
   // Import recording.
 
   let calltreeRendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   let imported = once(PerformanceController, EVENTS.RECORDING_IMPORTED);
-  await PerformanceController.importRecording("", file);
+  yield PerformanceController.importRecording("", file);
 
-  await imported;
+  yield imported;
   ok(true, "The profiler data appears to have been successfully imported.");
 
-  await calltreeRendered;
+  yield calltreeRendered;
   ok(true, "The imported data was re-rendered.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
-};
+});
 
 function getUnicodeConverter() {
   let className = "@mozilla.org/intl/scriptableunicodeconverter";
diff --git a/devtools/client/performance/test/browser_perf-refresh.js b/devtools/client/performance/test/browser_perf-refresh.js
index 06d5fc0c0635..825e2153fa3a 100644
--- a/devtools/client/performance/test/browser_perf-refresh.js
+++ b/devtools/client/performance/test/browser_perf-refresh.js
@@ -11,16 +11,16 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording, reload } = require("devtools/client/performance/test/helpers/actions");
 const { waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 
-add_task(async function () {
-  let { panel, target } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel, target } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { PerformanceController } = panel.panelWin;
 
-  await startRecording(panel);
-  await reload(target);
+  yield startRecording(panel);
+  yield reload(target);
 
   let recording = PerformanceController.getCurrentRecording();
   let markersLength = recording.getAllData().markers.length;
@@ -28,9 +28,9 @@ add_task(async function () {
   ok(recording.isRecording(),
     "RecordingModel should still be recording after reload");
 
-  await waitUntil(() => recording.getMarkers().length > markersLength);
+  yield waitUntil(() => recording.getMarkers().length > markersLength);
   ok("Markers continue after reload.");
 
-  await stopRecording(panel);
-  await teardownToolboxAndRemoveTab(panel);
+  yield stopRecording(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-states.js b/devtools/client/performance/test/browser_perf-states.js
index 48e2dd64037b..c01fb31213b4 100644
--- a/devtools/client/performance/test/browser_perf-states.js
+++ b/devtools/client/performance/test/browser_perf-states.js
@@ -11,8 +11,8 @@ const { UI_ENABLE_MEMORY_PREF, UI_ENABLE_ALLOCATIONS_PREF } = require("devtools/
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -50,7 +50,7 @@ add_task(async function () {
   ok(!(OverviewView.graphs.get("framerate")),
     "The framerate graph should still not have been created yet.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
   is(PerformanceView.getState(), "recording",
     "The current state of the performance panel view is 'recording'.");
@@ -59,7 +59,7 @@ add_task(async function () {
   ok(OverviewView.graphs.get("framerate"),
     "The framerate graph should have been created now.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   is(PerformanceView.getState(), "recorded",
     "The current state of the performance panel view is 'recorded'.");
@@ -72,7 +72,7 @@ add_task(async function () {
   ok(!DetailsView.components["memory-flamegraph"].initialized,
     "The memory-flamegraph detail view should still not have been created yet.");
 
-  await DetailsView.selectView("js-calltree");
+  yield DetailsView.selectView("js-calltree");
 
   is(PerformanceView.getState(), "recorded",
     "The current state of the performance panel view is still 'recorded'.");
@@ -85,7 +85,7 @@ add_task(async function () {
   ok(!DetailsView.components["memory-flamegraph"].initialized,
     "The memory-flamegraph detail view should still not have been created yet.");
 
-  await DetailsView.selectView("memory-calltree");
+  yield DetailsView.selectView("memory-calltree");
 
   is(PerformanceView.getState(), "recorded",
     "The current state of the performance panel view is still 'recorded'.");
@@ -98,5 +98,5 @@ add_task(async function () {
   ok(!DetailsView.components["memory-flamegraph"].initialized,
     "The memory-flamegraph detail view should still not have been created yet.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-telemetry-01.js b/devtools/client/performance/test/browser_perf-telemetry-01.js
index 5fd2165deaa0..2c37e6c5ae15 100644
--- a/devtools/client/performance/test/browser_perf-telemetry-01.js
+++ b/devtools/client/performance/test/browser_perf-telemetry-01.js
@@ -12,8 +12,8 @@ const { UI_ENABLE_MEMORY_PREF } = require("devtools/client/performance/test/help
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -29,13 +29,13 @@ add_task(async function () {
 
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, false);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   Services.prefs.setBoolPref(UI_ENABLE_MEMORY_PREF, true);
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   is(logs[DURATION].length, 2, `There are two entries for ${DURATION}.`);
   ok(logs[DURATION].every(d => typeof d === "number"),
@@ -49,5 +49,5 @@ add_task(async function () {
   ok(logs[FEATURES].find(r => r[0] === "withMemory" && r[1] === false),
     "One feature entry for memory disabled.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-telemetry-02.js b/devtools/client/performance/test/browser_perf-telemetry-02.js
index 9306a82cb5c7..6fe268e3a153 100644
--- a/devtools/client/performance/test/browser_perf-telemetry-02.js
+++ b/devtools/client/performance/test/browser_perf-telemetry-02.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -25,24 +25,24 @@ add_task(async function () {
   let EXPORTED = "DEVTOOLS_PERFTOOLS_RECORDING_EXPORT_FLAG";
   let IMPORTED = "DEVTOOLS_PERFTOOLS_RECORDING_IMPORT_FLAG";
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let file = FileUtils.getFile("TmpD", ["tmpprofile.json"]);
   file.createUnique(Ci.nsIFile.NORMAL_FILE_TYPE, parseInt("666", 8));
 
   let exported = once(PerformanceController, EVENTS.RECORDING_EXPORTED);
-  await PerformanceController.exportRecording("",
+  yield PerformanceController.exportRecording("",
     PerformanceController.getCurrentRecording(), file);
-  await exported;
+  yield exported;
 
   ok(logs[EXPORTED], `A telemetry entry for ${EXPORTED} exists after exporting.`);
 
   let imported = once(PerformanceController, EVENTS.RECORDING_IMPORTED);
-  await PerformanceController.importRecording(null, file);
-  await imported;
+  yield PerformanceController.importRecording(null, file);
+  yield imported;
 
   ok(logs[IMPORTED], `A telemetry entry for ${IMPORTED} exists after importing.`);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-telemetry-03.js b/devtools/client/performance/test/browser_perf-telemetry-03.js
index 102265e6ec3f..a10f314d2424 100644
--- a/devtools/client/performance/test/browser_perf-telemetry-03.js
+++ b/devtools/client/performance/test/browser_perf-telemetry-03.js
@@ -12,8 +12,8 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
@@ -30,20 +30,20 @@ add_task(async function () {
   let logs = telemetry.getLogs();
   let VIEWS = "DEVTOOLS_PERFTOOLS_SELECTED_VIEW_MS";
 
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
   let calltreeRendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
   let flamegraphRendered = once(JsFlameGraphView, EVENTS.UI_JS_FLAMEGRAPH_RENDERED);
 
   // Go through some views to check later.
-  await DetailsView.selectView("js-calltree");
-  await calltreeRendered;
+  yield DetailsView.selectView("js-calltree");
+  yield calltreeRendered;
 
-  await DetailsView.selectView("js-flamegraph");
-  await flamegraphRendered;
+  yield DetailsView.selectView("js-flamegraph");
+  yield flamegraphRendered;
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 
   // Check views after destruction to ensure `js-flamegraph` gets called
   // with a time during destruction.
diff --git a/devtools/client/performance/test/browser_perf-telemetry-04.js b/devtools/client/performance/test/browser_perf-telemetry-04.js
index cc702e9d4cef..362b5471425e 100644
--- a/devtools/client/performance/test/browser_perf-telemetry-04.js
+++ b/devtools/client/performance/test/browser_perf-telemetry-04.js
@@ -10,13 +10,13 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInTab, initConsoleInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { waitForRecordingStartedEvents, waitForRecordingStoppedEvents } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { target, console } = await initConsoleInNewTab({
+add_task(function* () {
+  let { target, console } = yield initConsoleInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
-  let { panel } = await initPerformanceInTab({ tab: target.tab });
+  let { panel } = yield initPerformanceInTab({ tab: target.tab });
   let { PerformanceController } = panel.panelWin;
 
   let telemetry = PerformanceController._telemetry;
@@ -29,15 +29,15 @@ add_task(async function () {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profile("rust");
-  await started;
+  yield console.profile("rust");
+  yield started;
 
   let stopped = waitForRecordingStoppedEvents(panel, {
     // only emitted for manual recordings
     skipWaitingForBackendReady: true
   });
-  await console.profileEnd("rust");
-  await stopped;
+  yield console.profileEnd("rust");
+  yield stopped;
 
   is(logs[DURATION].length, 1, `There is one entry for ${DURATION}.`);
   ok(logs[DURATION].every(d => typeof d === "number"),
@@ -46,5 +46,5 @@ add_task(async function () {
   is(logs[FEATURES].length, 4,
      `There is one recording worth of entries for ${FEATURES}.`);
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_perf-theme-toggle.js b/devtools/client/performance/test/browser_perf-theme-toggle.js
index b866e59b6a96..f8dbe97678cb 100644
--- a/devtools/client/performance/test/browser_perf-theme-toggle.js
+++ b/devtools/client/performance/test/browser_perf-theme-toggle.js
@@ -17,19 +17,19 @@ Services.prefs.setBoolPref(MEMORY_PREF, false);
 
 requestLongerTimeout(2);
 
-async function spawnTest() {
-  let { panel } = await initPerformance(SIMPLE_URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(SIMPLE_URL);
   let { EVENTS, $, OverviewView, document: doc } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   let markers = OverviewView.graphs.get("timeline");
   is(markers.backgroundColor, DARK_BG,
     "correct theme on load for markers.");
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   let refreshed = once(markers, "refresh");
   setTheme("light");
-  await refreshed;
+  yield refreshed;
 
   ok(true, "markers were rerendered after theme change.");
   is(markers.backgroundColor, LIGHT_BG,
@@ -38,24 +38,24 @@ async function spawnTest() {
   // reset back to dark
   refreshed = once(markers, "refresh");
   setTheme("dark");
-  await refreshed;
+  yield refreshed;
 
   info("Testing with memory overview");
 
   Services.prefs.setBoolPref(MEMORY_PREF, true);
 
-  await startRecording(panel);
+  yield startRecording(panel);
   let memory = OverviewView.graphs.get("memory");
   is(memory.backgroundColor, DARK_BG,
     "correct theme on load for memory.");
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   refreshed = Promise.all([
     once(markers, "refresh"),
     once(memory, "refresh"),
   ]);
   setTheme("light");
-  await refreshed;
+  yield refreshed;
 
   ok(true, "Both memory and markers were rerendered after theme change.");
   is(markers.backgroundColor, LIGHT_BG,
@@ -70,9 +70,9 @@ async function spawnTest() {
 
   // Set theme back to light
   setTheme("light");
-  await refreshed;
+  yield refreshed;
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 /* eslint-enable */
diff --git a/devtools/client/performance/test/browser_perf-tree-abstract-01.js b/devtools/client/performance/test/browser_perf-tree-abstract-01.js
index acbbf766bd28..61fc32a1dbcb 100644
--- a/devtools/client/performance/test/browser_perf-tree-abstract-01.js
+++ b/devtools/client/performance/test/browser_perf-tree-abstract-01.js
@@ -11,11 +11,11 @@ const { appendAndWaitForPaint } = require("devtools/client/performance/test/help
 const { synthesizeCustomTreeClass } = require("devtools/client/performance/test/helpers/synth-utils");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
+add_task(function* () {
   let { MyCustomTreeItem, myDataSrc } = synthesizeCustomTreeClass();
 
   let container = document.createElement("vbox");
-  await appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
+  yield appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
 
   // Populate the tree and test the root item...
 
@@ -51,11 +51,11 @@ add_task(async function () {
   let receivedFocusEvent = once(treeRoot, "focus");
   mousedown(treeRoot.target.querySelector(".arrow"));
 
-  let [eventItem] = await receivedExpandEvent;
+  let [eventItem] = yield receivedExpandEvent;
   is(eventItem, treeRoot,
     "The 'expand' event target is correct (1).");
 
-  await receivedFocusEvent;
+  yield receivedFocusEvent;
   is(document.commandDispatcher.focusedElement, treeRoot.target,
     "The root node is now focused.");
 
@@ -102,7 +102,7 @@ add_task(async function () {
   receivedFocusEvent = once(treeRoot, "focus", { spreadArgs: true });
   mousedown(fooItem.target);
 
-  [eventItem] = await receivedFocusEvent;
+  [eventItem] = yield receivedFocusEvent;
   is(eventItem, fooItem,
     "The 'focus' event target is correct (2).");
   is(document.commandDispatcher.focusedElement, fooItem.target,
@@ -114,11 +114,11 @@ add_task(async function () {
   receivedFocusEvent = once(treeRoot, "focus");
   dblclick(barItem.target);
 
-  [eventItem] = await receivedExpandEvent;
+  [eventItem] = yield receivedExpandEvent;
   is(eventItem, barItem,
     "The 'expand' event target is correct (3).");
 
-  await receivedFocusEvent;
+  yield receivedFocusEvent;
   is(document.commandDispatcher.focusedElement, barItem.target,
     "The 'foo' node is now focused.");
 
diff --git a/devtools/client/performance/test/browser_perf-tree-abstract-02.js b/devtools/client/performance/test/browser_perf-tree-abstract-02.js
index 1d068345cc60..62db4cfd6de2 100644
--- a/devtools/client/performance/test/browser_perf-tree-abstract-02.js
+++ b/devtools/client/performance/test/browser_perf-tree-abstract-02.js
@@ -10,11 +10,11 @@
 const { appendAndWaitForPaint } = require("devtools/client/performance/test/helpers/dom-utils");
 const { synthesizeCustomTreeClass } = require("devtools/client/performance/test/helpers/synth-utils");
 
-add_task(async function () {
+add_task(function* () {
   let { MyCustomTreeItem, myDataSrc } = synthesizeCustomTreeClass();
 
   let container = document.createElement("vbox");
-  await appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
+  yield appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
 
   // Populate the tree and test the root item...
 
diff --git a/devtools/client/performance/test/browser_perf-tree-abstract-03.js b/devtools/client/performance/test/browser_perf-tree-abstract-03.js
index c19f08f8f3f7..4e427fcd3f30 100644
--- a/devtools/client/performance/test/browser_perf-tree-abstract-03.js
+++ b/devtools/client/performance/test/browser_perf-tree-abstract-03.js
@@ -10,11 +10,11 @@
 const { appendAndWaitForPaint } = require("devtools/client/performance/test/helpers/dom-utils");
 const { synthesizeCustomTreeClass } = require("devtools/client/performance/test/helpers/synth-utils");
 
-add_task(async function () {
+add_task(function* () {
   let { MyCustomTreeItem, myDataSrc } = synthesizeCustomTreeClass();
 
   let container = document.createElement("vbox");
-  await appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
+  yield appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
 
   // Populate the tree by pressing RIGHT...
 
diff --git a/devtools/client/performance/test/browser_perf-tree-abstract-04.js b/devtools/client/performance/test/browser_perf-tree-abstract-04.js
index 2115a1cd4eb2..614235ab8317 100644
--- a/devtools/client/performance/test/browser_perf-tree-abstract-04.js
+++ b/devtools/client/performance/test/browser_perf-tree-abstract-04.js
@@ -10,11 +10,11 @@ const { appendAndWaitForPaint } = require("devtools/client/performance/test/help
 const { synthesizeCustomTreeClass } = require("devtools/client/performance/test/helpers/synth-utils");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
+add_task(function* () {
   let { MyCustomTreeItem, myDataSrc } = synthesizeCustomTreeClass();
 
   let container = document.createElement("vbox");
-  await appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
+  yield appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
 
   // Populate the tree and test the root item...
 
@@ -26,7 +26,7 @@ add_task(async function () {
 
   let receivedFocusEvent = once(treeRoot, "focus");
   dblclick(treeRoot.target.querySelector(".arrow"));
-  await receivedFocusEvent;
+  yield receivedFocusEvent;
 
   is(treeRoot.expanded, originalTreeRootExpandedState,
     "A double click on the arrow was ignored.");
diff --git a/devtools/client/performance/test/browser_perf-tree-abstract-05.js b/devtools/client/performance/test/browser_perf-tree-abstract-05.js
index 62000369138c..88138b6f35ce 100644
--- a/devtools/client/performance/test/browser_perf-tree-abstract-05.js
+++ b/devtools/client/performance/test/browser_perf-tree-abstract-05.js
@@ -10,13 +10,13 @@
 const { appendAndWaitForPaint } = require("devtools/client/performance/test/helpers/dom-utils");
 const { synthesizeCustomTreeClass } = require("devtools/client/performance/test/helpers/synth-utils");
 
-add_task(async function () {
+add_task(function* () {
   let { MyCustomTreeItem } = synthesizeCustomTreeClass();
 
   let container = document.createElement("vbox");
   container.style.height = "100%";
   container.style.overflow = "scroll";
-  await appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
+  yield appendAndWaitForPaint(gBrowser.selectedBrowser.parentNode, container);
 
   let myDataSrc = {
     label: "root",
diff --git a/devtools/client/performance/test/browser_perf-tree-view-06.js b/devtools/client/performance/test/browser_perf-tree-view-06.js
index 56ad879b8d4f..9d2fb6718c59 100644
--- a/devtools/client/performance/test/browser_perf-tree-view-06.js
+++ b/devtools/client/performance/test/browser_perf-tree-view-06.js
@@ -12,7 +12,7 @@ const { CallView } = require("devtools/client/performance/modules/widgets/tree-v
 const { synthesizeProfile } = require("devtools/client/performance/test/helpers/synth-utils");
 const { idleWait, waitUntil } = require("devtools/client/performance/test/helpers/wait-utils");
 
-add_task(async function () {
+add_task(function* () {
   let profile = synthesizeProfile();
   let threadNode = new ThreadNode(profile.threads[0], { startTime: 0, endTime: 20 });
 
@@ -38,14 +38,14 @@ add_task(async function () {
   rightMousedown(D.target.querySelector(".call-tree-url"));
 
   // Ensure link was not called for right click.
-  await idleWait(100);
+  yield idleWait(100);
   ok(!linkEvent, "The `link` event not fired for right click.");
 
   // Fire left click.
   mousedown(D.target.querySelector(".call-tree-url"));
 
   // Ensure link was called for left click.
-  await waitUntil(() => linkEvent);
+  yield waitUntil(() => linkEvent);
   is(linkEvent, D, "The `link` event target is correct.");
 
   treeRoot.off("link", handler);
diff --git a/devtools/client/performance/test/browser_perf-tree-view-11.js b/devtools/client/performance/test/browser_perf-tree-view-11.js
index 3a25f6c1dcf0..a316098e3272 100644
--- a/devtools/client/performance/test/browser_perf-tree-view-11.js
+++ b/devtools/client/performance/test/browser_perf-tree-view-11.js
@@ -9,8 +9,8 @@
 
 var { CATEGORY_MASK } = require("devtools/client/performance/modules/categories");
 
-async function spawnTest() {
-  let { panel } = await initPerformance(SIMPLE_URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(SIMPLE_URL);
   let { EVENTS, $, $$, window, PerformanceController } = panel.panelWin;
   let { OverviewView, DetailsView, JsCallTreeView } = panel.panelWin;
 
@@ -22,12 +22,12 @@ async function spawnTest() {
 
   // Make two recordings, so we have one to switch to later, as the
   // second one will have fake sample data
-  await startRecording(panel);
-  await stopRecording(panel);
+  yield startRecording(panel);
+  yield stopRecording(panel);
 
-  await DetailsView.selectView("js-calltree");
+  yield DetailsView.selectView("js-calltree");
 
-  await injectAndRenderProfilerData();
+  yield injectAndRenderProfilerData();
 
   let rows = $$("#js-calltree-view .call-tree-item");
   is(rows.length, 4, "4 call tree rows exist");
@@ -52,10 +52,10 @@ async function spawnTest() {
     }
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 
-  async function injectAndRenderProfilerData() {
+  function* injectAndRenderProfilerData() {
     // Get current recording and inject our mock data
     info("Injecting mock profile data");
     let recording = PerformanceController.getCurrentRecording();
@@ -64,7 +64,7 @@ async function spawnTest() {
     // Force a rerender
     let rendered = once(JsCallTreeView, EVENTS.UI_JS_CALL_TREE_RENDERED);
     JsCallTreeView.render(OverviewView.getTimeInterval());
-    await rendered;
+    yield rendered;
   }
 }
 
diff --git a/devtools/client/performance/test/browser_perf-ui-recording.js b/devtools/client/performance/test/browser_perf-ui-recording.js
index c1265f4c3dea..b585f763bb24 100644
--- a/devtools/client/performance/test/browser_perf-ui-recording.js
+++ b/devtools/client/performance/test/browser_perf-ui-recording.js
@@ -12,28 +12,28 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   pmmLoadFrameScripts(gBrowser);
 
-  ok(!(await pmmIsProfilerActive()),
+  ok(!(yield pmmIsProfilerActive()),
     "The built-in profiler module should not have been automatically started.");
 
-  await startRecording(panel);
+  yield startRecording(panel);
 
-  ok((await pmmIsProfilerActive()),
+  ok((yield pmmIsProfilerActive()),
     "The built-in profiler module should now be active.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
-  ok((await pmmIsProfilerActive()),
+  ok((yield pmmIsProfilerActive()),
     "The built-in profiler module should still be active.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 
   pmmClearFrameScripts();
 });
diff --git a/devtools/client/performance/test/browser_timeline-filters-01.js b/devtools/client/performance/test/browser_timeline-filters-01.js
index ff9698cbf8e4..4a8d485852fa 100644
--- a/devtools/client/performance/test/browser_timeline-filters-01.js
+++ b/devtools/client/performance/test/browser_timeline-filters-01.js
@@ -8,16 +8,16 @@
 
 const EPSILON = 0.00000001;
 
-async function spawnTest() {
-  let { panel } = await initPerformance(SIMPLE_URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(SIMPLE_URL);
   let { $, $$, EVENTS, PerformanceController, OverviewView, WaterfallView } = panel.panelWin;
   let { TimelineGraph } = require("devtools/client/performance/modules/widgets/graphs");
   let { rowHeight: MARKERS_GRAPH_ROW_HEIGHT } = TimelineGraph.prototype;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     // Wait until we get 3 different markers.
     let markers = PerformanceController.getCurrentRecording().getMarkers();
     return markers.some(m => m.name == "Styles") &&
@@ -25,7 +25,7 @@ async function spawnTest() {
            markers.some(m => m.name == "Paint");
   });
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   // Push some fake markers of a type we do not have a blueprint for
@@ -50,7 +50,7 @@ async function spawnTest() {
   let overview = OverviewView.graphs.get("timeline");
   let originalHeight = overview.fixedHeight;
 
-  await waterfallRendered;
+  yield waterfallRendered;
 
   ok($(".waterfall-marker-bar[type=Styles]"), "Found at least one 'Styles' marker (1)");
   ok($(".waterfall-marker-bar[type=Reflow]"), "Found at least one 'Reflow' marker (1)");
@@ -59,7 +59,7 @@ async function spawnTest() {
 
   let heightBefore = overview.fixedHeight;
   EventUtils.synthesizeMouseAtCenter(menuItem1, {type: "mouseup"}, panel.panelWin);
-  await waitForOverviewAndCommand(overview, menuItem1);
+  yield waitForOverviewAndCommand(overview, menuItem1);
 
   is(overview.fixedHeight, heightBefore, "Overview height hasn't changed");
   ok(!$(".waterfall-marker-bar[type=Styles]"), "No 'Styles' marker (2)");
@@ -69,7 +69,7 @@ async function spawnTest() {
 
   heightBefore = overview.fixedHeight;
   EventUtils.synthesizeMouseAtCenter(menuItem2, {type: "mouseup"}, panel.panelWin);
-  await waitForOverviewAndCommand(overview, menuItem2);
+  yield waitForOverviewAndCommand(overview, menuItem2);
 
   is(overview.fixedHeight, heightBefore, "Overview height hasn't changed");
   ok(!$(".waterfall-marker-bar[type=Styles]"), "No 'Styles' marker (3)");
@@ -79,7 +79,7 @@ async function spawnTest() {
 
   heightBefore = overview.fixedHeight;
   EventUtils.synthesizeMouseAtCenter(menuItem3, {type: "mouseup"}, panel.panelWin);
-  await waitForOverviewAndCommand(overview, menuItem3);
+  yield waitForOverviewAndCommand(overview, menuItem3);
 
   is(overview.fixedHeight, heightBefore - MARKERS_GRAPH_ROW_HEIGHT, "Overview is smaller");
   ok(!$(".waterfall-marker-bar[type=Styles]"), "No 'Styles' marker (4)");
@@ -88,7 +88,7 @@ async function spawnTest() {
   ok($(".waterfall-marker-bar[type=CustomMarker]"), "Found at least one 'Unknown' marker (4)");
 
   EventUtils.synthesizeMouseAtCenter(menuItem4, {type: "mouseup"}, panel.panelWin);
-  await waitForOverviewAndCommand(overview, menuItem4);
+  yield waitForOverviewAndCommand(overview, menuItem4);
 
   ok(!$(".waterfall-marker-bar[type=Styles]"), "No 'Styles' marker (5)");
   ok(!$(".waterfall-marker-bar[type=Reflow]"), "No 'Reflow' marker (5)");
@@ -97,7 +97,7 @@ async function spawnTest() {
 
   for (let item of [menuItem1, menuItem2, menuItem3]) {
     EventUtils.synthesizeMouseAtCenter(item, {type: "mouseup"}, panel.panelWin);
-    await waitForOverviewAndCommand(overview, item);
+    yield waitForOverviewAndCommand(overview, item);
   }
 
   ok($(".waterfall-marker-bar[type=Styles]"), "Found at least one 'Styles' marker (6)");
@@ -107,7 +107,7 @@ async function spawnTest() {
 
   is(overview.fixedHeight, originalHeight, "Overview restored");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/performance/test/browser_timeline-filters-02.js b/devtools/client/performance/test/browser_timeline-filters-02.js
index 6d94853dc60a..f9ab00711913 100644
--- a/devtools/client/performance/test/browser_timeline-filters-02.js
+++ b/devtools/client/performance/test/browser_timeline-filters-02.js
@@ -8,32 +8,32 @@
 
 const URL = EXAMPLE_URL + "doc_innerHTML.html";
 
-async function spawnTest() {
-  let { panel } = await initPerformance(URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(URL);
   let { $, $$, EVENTS, PerformanceController, OverviewView, WaterfallView } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     let markers = PerformanceController.getCurrentRecording().getMarkers();
     return markers.some(m => m.name == "Parse HTML") &&
            markers.some(m => m.name == "Javascript");
   });
 
   let waterfallRendered = WaterfallView.once(EVENTS.UI_WATERFALL_RENDERED);
-  await stopRecording(panel);
+  yield stopRecording(panel);
 
   $("#filter-button").click();
   let filterJS = $("menuitem[marker-type=Javascript]");
 
-  await waterfallRendered;
+  yield waterfallRendered;
 
   ok($(".waterfall-marker-bar[type=Javascript]"), "Found at least one 'Javascript' marker");
   ok(!$(".waterfall-marker-bar[type='Parse HTML']"), "Found no Parse HTML markers as they are nested still");
 
   EventUtils.synthesizeMouseAtCenter(filterJS, {type: "mouseup"}, panel.panelWin);
-  await Promise.all([
+  yield Promise.all([
     WaterfallView.once(EVENTS.UI_WATERFALL_RENDERED),
     once(filterJS, "command")
   ]);
@@ -42,7 +42,7 @@ async function spawnTest() {
   ok($(".waterfall-marker-bar[type='Parse HTML']"),
     "Found at least one 'Parse HTML' marker still visible after hiding JS markers");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 /* eslint-enable */
diff --git a/devtools/client/performance/test/browser_timeline-waterfall-background.js b/devtools/client/performance/test/browser_timeline-waterfall-background.js
index 6d4de73a27e8..85d5bd28cb62 100644
--- a/devtools/client/performance/test/browser_timeline-waterfall-background.js
+++ b/devtools/client/performance/test/browser_timeline-waterfall-background.js
@@ -11,21 +11,21 @@ const { SIMPLE_URL } = require("devtools/client/performance/test/helpers/urls");
 const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtools/client/performance/test/helpers/panel-utils");
 const { startRecording, stopRecording, waitForOverviewRenderedWithMarkers } = require("devtools/client/performance/test/helpers/actions");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { WaterfallView } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
   // Ensure overview is rendering and some markers were received.
-  await waitForOverviewRenderedWithMarkers(panel);
+  yield waitForOverviewRenderedWithMarkers(panel);
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   // Test the waterfall background.
@@ -37,5 +37,5 @@ add_task(async function () {
   is(WaterfallView.canvas.height, 1,
     "The canvas height is correct.");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_timeline-waterfall-generic.js b/devtools/client/performance/test/browser_timeline-waterfall-generic.js
index ff76a475968a..bcb87d80ca9e 100644
--- a/devtools/client/performance/test/browser_timeline-waterfall-generic.js
+++ b/devtools/client/performance/test/browser_timeline-waterfall-generic.js
@@ -11,21 +11,21 @@ const { initPerformanceInNewTab, teardownToolboxAndRemoveTab } = require("devtoo
 const { startRecording, stopRecording, waitForOverviewRenderedWithMarkers } = require("devtools/client/performance/test/helpers/actions");
 const { once } = require("devtools/client/performance/test/helpers/event-utils");
 
-add_task(async function () {
-  let { panel } = await initPerformanceInNewTab({
+add_task(function* () {
+  let { panel } = yield initPerformanceInNewTab({
     url: SIMPLE_URL,
     win: window
   });
 
   let { $, $$, EVENTS, WaterfallView } = panel.panelWin;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
   // Ensure overview is rendering and some markers were received.
-  await waitForOverviewRenderedWithMarkers(panel);
+  yield waitForOverviewRenderedWithMarkers(panel);
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   // Test the header container.
@@ -82,7 +82,7 @@ add_task(async function () {
 
   let waterfallRerendered = once(WaterfallView, EVENTS.UI_WATERFALL_RENDERED);
   $$(".waterfall-tree-item")[0].click();
-  await waterfallRerendered;
+  yield waterfallRerendered;
 
   let parentWidthAfter = $("#waterfall-view").getBoundingClientRect().width;
   let sidebarWidthAfter = $(".waterfall-sidebar").getBoundingClientRect().width;
@@ -101,5 +101,5 @@ add_task(async function () {
                       - WaterfallView.WATERFALL_MARKER_SIDEBAR_SAFE_BOUNDS,
      "The waterfall width is correct (2).");
 
-  await teardownToolboxAndRemoveTab(panel);
+  yield teardownToolboxAndRemoveTab(panel);
 });
diff --git a/devtools/client/performance/test/browser_timeline-waterfall-rerender.js b/devtools/client/performance/test/browser_timeline-waterfall-rerender.js
index 955ad3038f39..8bf842560c88 100644
--- a/devtools/client/performance/test/browser_timeline-waterfall-rerender.js
+++ b/devtools/client/performance/test/browser_timeline-waterfall-rerender.js
@@ -5,25 +5,25 @@
  * Tests if the waterfall remembers the selection when rerendering.
  */
 
-async function spawnTest() {
-  let { target, panel } = await initPerformance(SIMPLE_URL);
+function* spawnTest() {
+  let { target, panel } = yield initPerformance(SIMPLE_URL);
   let { $, $$, EVENTS, PerformanceController, OverviewView, WaterfallView } = panel.panelWin;
 
   const MIN_MARKERS_COUNT = 50;
   const MAX_MARKERS_SELECT = 20;
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
   let updated = 0;
   OverviewView.on(EVENTS.UI_OVERVIEW_RENDERED, () => updated++);
 
-  ok((await waitUntil(() => updated > 0)),
+  ok((yield waitUntil(() => updated > 0)),
     "The overview graphs were updated a bunch of times.");
-  ok((await waitUntil(() => PerformanceController.getCurrentRecording().getMarkers().length > MIN_MARKERS_COUNT)),
+  ok((yield waitUntil(() => PerformanceController.getCurrentRecording().getMarkers().length > MIN_MARKERS_COUNT)),
     "There are some markers available.");
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   let currentMarkers = PerformanceController.getCurrentRecording().getMarkers();
@@ -35,7 +35,7 @@ async function spawnTest() {
   // Select a portion of the overview.
   let rerendered = WaterfallView.once(EVENTS.UI_WATERFALL_RENDERED);
   OverviewView.setTimeInterval({ startTime: 0, endTime: currentMarkers[MAX_MARKERS_SELECT].end });
-  await rerendered;
+  yield rerendered;
 
   ok(!$(".waterfall-tree-item:focus"),
     "There is no item focused in the waterfall yet.");
@@ -58,7 +58,7 @@ async function spawnTest() {
   // Simulate a resize on the marker details.
   rerendered = WaterfallView.once(EVENTS.UI_WATERFALL_RENDERED);
   EventUtils.sendMouseEvent({ type: "mouseup" }, WaterfallView.detailsSplitter);
-  await rerendered;
+  yield rerendered;
 
   let afterResizeBarsCount = $$(".waterfall-marker-bar").length;
   info("After resize bars count: " + afterResizeBarsCount);
@@ -70,7 +70,7 @@ async function spawnTest() {
   ok(!$("#waterfall-details").hidden,
     "The waterfall sidebar is still visible.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 /* eslint-enable */
diff --git a/devtools/client/performance/test/browser_timeline-waterfall-sidebar.js b/devtools/client/performance/test/browser_timeline-waterfall-sidebar.js
index 3353ac69c3cf..5a933f7ad11d 100644
--- a/devtools/client/performance/test/browser_timeline-waterfall-sidebar.js
+++ b/devtools/client/performance/test/browser_timeline-waterfall-sidebar.js
@@ -5,8 +5,8 @@
  * Tests if the sidebar is properly updated when a marker is selected.
  */
 
-async function spawnTest() {
-  let { target, panel } = await initPerformance(SIMPLE_URL);
+function* spawnTest() {
+  let { target, panel } = yield initPerformance(SIMPLE_URL);
   let { $, $$, PerformanceController, WaterfallView } = panel.panelWin;
   let { L10N } = require("devtools/client/performance/modules/global");
   let { MarkerBlueprintUtils } = require("devtools/client/performance/modules/marker-blueprint-utils");
@@ -19,10 +19,10 @@ async function spawnTest() {
     return { submarkers: markers };
   };
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     // Wait until we get 3 different markers.
     let markers = PerformanceController.getCurrentRecording().getMarkers();
     return markers.some(m => m.name == "Styles") &&
@@ -30,7 +30,7 @@ async function spawnTest() {
            markers.some(m => m.name == "Paint");
   });
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   info("No need to select everything in the timeline.");
@@ -71,7 +71,7 @@ async function spawnTest() {
     ok(tooltip.includes(toMs(mkr.end)), "Tooltip has end time.");
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 /* eslint-enable */
diff --git a/devtools/client/performance/test/browser_timeline-waterfall-workers.js b/devtools/client/performance/test/browser_timeline-waterfall-workers.js
index 505b81d3ea7a..73e61cd0d78f 100644
--- a/devtools/client/performance/test/browser_timeline-waterfall-workers.js
+++ b/devtools/client/performance/test/browser_timeline-waterfall-workers.js
@@ -6,18 +6,18 @@
  * Tests if the sidebar is properly updated with worker markers.
  */
 
-async function spawnTest() {
-  let { panel } = await initPerformance(WORKER_URL);
+function* spawnTest() {
+  let { panel } = yield initPerformance(WORKER_URL);
   let { $$, $, PerformanceController } = panel.panelWin;
 
   loadFrameScripts();
 
-  await startRecording(panel);
+  yield startRecording(panel);
   ok(true, "Recording has started.");
 
   evalInDebuggee("performWork()");
 
-  await waitUntil(() => {
+  yield waitUntil(() => {
     // Wait until we get the worker markers.
     let markers = PerformanceController.getCurrentRecording().getMarkers();
     if (!markers.some(m => m.name == "Worker") ||
@@ -32,14 +32,14 @@ async function spawnTest() {
     return true;
   });
 
-  await stopRecording(panel);
+  yield stopRecording(panel);
   ok(true, "Recording has ended.");
 
   for (let node of $$(".waterfall-marker-name[value=Worker")) {
     testWorkerMarkerUI(node.parentNode.parentNode);
   }
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/performance/test/helpers/panel-utils.js b/devtools/client/performance/test/helpers/panel-utils.js
index fc956793c0ea..468a86607825 100644
--- a/devtools/client/performance/test/helpers/panel-utils.js
+++ b/devtools/client/performance/test/helpers/panel-utils.js
@@ -12,25 +12,25 @@ const { once } = require("devtools/client/performance/test/helpers/event-utils")
 /**
  * Initializes a toolbox panel in a new tab.
  */
-exports.initPanelInNewTab = async function ({ tool, url, win }, options = {}) {
-  let tab = await addTab({ url, win }, options);
-  return exports.initPanelInTab({ tool, tab });
+exports.initPanelInNewTab = function* ({ tool, url, win }, options = {}) {
+  let tab = yield addTab({ url, win }, options);
+  return (yield exports.initPanelInTab({ tool, tab }));
 };
 
 /**
  * Initializes a toolbox panel in the specified tab.
  */
-exports.initPanelInTab = async function ({ tool, tab }) {
+exports.initPanelInTab = function* ({ tool, tab }) {
   dump(`Initializing a ${tool} panel.\n`);
 
   let target = TargetFactory.forTab(tab);
-  await target.makeRemote();
+  yield target.makeRemote();
 
   // Open a toolbox and wait for the connection to the performance actors
   // to be opened. This is necessary because of the WebConsole's
   // `profile` and `profileEnd` methods.
-  let toolbox = await gDevTools.showToolbox(target, tool);
-  await toolbox.initPerformance();
+  let toolbox = yield gDevTools.showToolbox(target, tool);
+  yield toolbox.initPerformance();
 
   let panel = toolbox.getCurrentPanel();
   return { target, toolbox, panel };
@@ -39,56 +39,56 @@ exports.initPanelInTab = async function ({ tool, tab }) {
 /**
  * Initializes a performance panel in a new tab.
  */
-exports.initPerformanceInNewTab = async function ({ url, win }, options = {}) {
-  let tab = await addTab({ url, win }, options);
-  return exports.initPerformanceInTab({ tab });
+exports.initPerformanceInNewTab = function* ({ url, win }, options = {}) {
+  let tab = yield addTab({ url, win }, options);
+  return (yield exports.initPerformanceInTab({ tab }));
 };
 
 /**
  * Initializes a performance panel in the specified tab.
  */
-exports.initPerformanceInTab = async function ({ tab }) {
-  return exports.initPanelInTab({
+exports.initPerformanceInTab = function* ({ tab }) {
+  return (yield exports.initPanelInTab({
     tool: "performance",
     tab: tab
-  });
+  }));
 };
 
 /**
  * Initializes a webconsole panel in a new tab.
  * Returns a console property that allows calls to `profile` and `profileEnd`.
  */
-exports.initConsoleInNewTab = async function ({ url, win }, options = {}) {
-  let tab = await addTab({ url, win }, options);
-  return exports.initConsoleInTab({ tab });
+exports.initConsoleInNewTab = function* ({ url, win }, options = {}) {
+  let tab = yield addTab({ url, win }, options);
+  return (yield exports.initConsoleInTab({ tab }));
 };
 
 /**
  * Initializes a webconsole panel in the specified tab.
  * Returns a console property that allows calls to `profile` and `profileEnd`.
  */
-exports.initConsoleInTab = async function ({ tab }) {
-  let { target, toolbox, panel } = await exports.initPanelInTab({
+exports.initConsoleInTab = function* ({ tab }) {
+  let { target, toolbox, panel } = yield exports.initPanelInTab({
     tool: "webconsole",
     tab: tab
   });
 
-  let consoleMethod = async function (method, label, event) {
+  let consoleMethod = function* (method, label, event) {
     let recordingEventReceived = once(toolbox.performance, event);
     if (label === undefined) {
-      await panel.hud.jsterm.execute(`console.${method}()`);
+      yield panel.hud.jsterm.execute(`console.${method}()`);
     } else {
-      await panel.hud.jsterm.execute(`console.${method}("${label}")`);
+      yield panel.hud.jsterm.execute(`console.${method}("${label}")`);
     }
-    await recordingEventReceived;
+    yield recordingEventReceived;
   };
 
-  let profile = async function (label) {
-    return consoleMethod("profile", label, "recording-started");
+  let profile = function* (label) {
+    return yield consoleMethod("profile", label, "recording-started");
   };
 
-  let profileEnd = async function (label) {
-    return consoleMethod("profileEnd", label, "recording-stopped");
+  let profileEnd = function* (label) {
+    return yield consoleMethod("profileEnd", label, "recording-stopped");
   };
 
   return { target, toolbox, panel, console: { profile, profileEnd } };
@@ -97,10 +97,10 @@ exports.initConsoleInTab = async function ({ tab }) {
 /**
  * Tears down a toolbox panel and removes an associated tab.
  */
-exports.teardownToolboxAndRemoveTab = async function (panel, options) {
+exports.teardownToolboxAndRemoveTab = function* (panel, options) {
   dump("Destroying panel.\n");
 
   let tab = panel.target.tab;
-  await panel.toolbox.destroy();
-  await removeTab(tab, options);
+  yield panel.toolbox.destroy();
+  yield removeTab(tab, options);
 };
diff --git a/devtools/client/performance/test/helpers/profiler-mm-utils.js b/devtools/client/performance/test/helpers/profiler-mm-utils.js
index fd63b4935281..4718115d452e 100644
--- a/devtools/client/performance/test/helpers/profiler-mm-utils.js
+++ b/devtools/client/performance/test/helpers/profiler-mm-utils.js
@@ -10,6 +10,7 @@
  */
 
 const { Cc, Ci } = require("chrome");
+const { Task } = require("devtools/shared/task");
 
 const FRAME_SCRIPT_UTILS_URL = "chrome://mochitests/content/browser/devtools/client/shared/test/frame-script-utils.js";
 
@@ -65,24 +66,24 @@ exports.pmmIsProfilerActive = () => {
 /**
  * Starts the nsProfiler module.
  */
-exports.pmmStartProfiler = async function ({ entries, interval, features }) {
-  let isActive = (await exports.pmmSendProfilerCommand("IsActive")).isActive;
+exports.pmmStartProfiler = Task.async(function* ({ entries, interval, features }) {
+  let isActive = (yield exports.pmmSendProfilerCommand("IsActive")).isActive;
   if (!isActive) {
     return exports.pmmSendProfilerCommand("StartProfiler", [entries, interval, features,
                                                             features.length]);
   }
   return null;
-};
+});
 /**
  * Stops the nsProfiler module.
  */
-exports.pmmStopProfiler = async function () {
-  let isActive = (await exports.pmmSendProfilerCommand("IsActive")).isActive;
+exports.pmmStopProfiler = Task.async(function* () {
+  let isActive = (yield exports.pmmSendProfilerCommand("IsActive")).isActive;
   if (isActive) {
     return exports.pmmSendProfilerCommand("StopProfiler");
   }
   return null;
-};
+});
 
 /**
  * Calls a method on the nsProfiler module.
diff --git a/devtools/client/performance/test/helpers/tab-utils.js b/devtools/client/performance/test/helpers/tab-utils.js
index 47db4ebae5d0..e1857fb36add 100644
--- a/devtools/client/performance/test/helpers/tab-utils.js
+++ b/devtools/client/performance/test/helpers/tab-utils.js
@@ -50,9 +50,9 @@ exports.removeTab = function (tab, options = {}) {
 /**
  * Adds a browser window with the provided options.
  */
-exports.addWindow = async function (options) {
+exports.addWindow = function* (options) {
   let { OpenBrowserWindow } = Services.wm.getMostRecentWindow(gDevTools.chromeWindowType);
   let win = OpenBrowserWindow(options);
-  await waitForDelayedStartupFinished(win);
+  yield waitForDelayedStartupFinished(win);
   return win;
 };
diff --git a/devtools/client/performance/test/helpers/wait-utils.js b/devtools/client/performance/test/helpers/wait-utils.js
index 52e252b7c9d8..be654b7d8c48 100644
--- a/devtools/client/performance/test/helpers/wait-utils.js
+++ b/devtools/client/performance/test/helpers/wait-utils.js
@@ -5,6 +5,7 @@
 /* globals dump */
 
 const { CC } = require("chrome");
+const { Task } = require("devtools/shared/task");
 const DevToolsUtils = require("devtools/shared/DevToolsUtils");
 const { once, observeOnce } = require("devtools/client/performance/test/helpers/event-utils");
 
@@ -33,13 +34,13 @@ exports.idleWait = function (time) {
 /**
  * Waits until a predicate returns true.
  */
-exports.waitUntil = async function (predicate, interval = 100, tries = 100) {
+exports.waitUntil = function* (predicate, interval = 100, tries = 100) {
   for (let i = 1; i <= tries; i++) {
-    if (await predicate()) {
+    if (yield Task.spawn(predicate)) {
       dump(`Predicate returned true after ${i} tries.\n`);
       return;
     }
-    await exports.idleWait(interval);
+    yield exports.idleWait(interval);
   }
   throw new Error(`Predicate returned false after ${tries} tries, aborting.\n`);
 };
diff --git a/devtools/client/performance/views/details-abstract-subview.js b/devtools/client/performance/views/details-abstract-subview.js
index 69d2962b7df1..f3f36cb3095a 100644
--- a/devtools/client/performance/views/details-abstract-subview.js
+++ b/devtools/client/performance/views/details-abstract-subview.js
@@ -33,11 +33,11 @@ var DetailsSubview = {
       this._wasRendered = true;
     };
 
-    this.render = async function (...args) {
-      let maybeRetval = await originalRenderFn.apply(self, args);
+    this.render = Task.async(function* (...args) {
+      let maybeRetval = yield originalRenderFn.apply(self, args);
       afterRenderFn();
       return maybeRetval;
-    };
+    });
   },
 
   /**
diff --git a/devtools/client/performance/views/details-js-flamegraph.js b/devtools/client/performance/views/details-js-flamegraph.js
index b3a411ed9dc2..0e40a37c5073 100644
--- a/devtools/client/performance/views/details-js-flamegraph.js
+++ b/devtools/client/performance/views/details-js-flamegraph.js
@@ -24,32 +24,32 @@ var JsFlameGraphView = extend(DetailsSubview, {
   /**
    * Sets up the view with event binding.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     DetailsSubview.initialize.call(this);
 
     this.graph = new FlameGraph($("#js-flamegraph-view"));
     this.graph.timelineTickUnits = L10N.getStr("graphs.ms");
     this.graph.setTheme(PerformanceController.getTheme());
-    await this.graph.ready();
+    yield this.graph.ready();
 
     this._onRangeChangeInGraph = this._onRangeChangeInGraph.bind(this);
     this._onThemeChanged = this._onThemeChanged.bind(this);
 
     PerformanceController.on(EVENTS.THEME_CHANGED, this._onThemeChanged);
     this.graph.on("selecting", this._onRangeChangeInGraph);
-  },
+  }),
 
   /**
    * Unbinds events.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     DetailsSubview.destroy.call(this);
 
     PerformanceController.off(EVENTS.THEME_CHANGED, this._onThemeChanged);
     this.graph.off("selecting", this._onRangeChangeInGraph);
 
-    await this.graph.destroy();
-  },
+    yield this.graph.destroy();
+  }),
 
   /**
    * Method for handling all the set up for rendering a new flamegraph.
diff --git a/devtools/client/performance/views/details-memory-flamegraph.js b/devtools/client/performance/views/details-memory-flamegraph.js
index 9ac49eda57d2..b73250529043 100644
--- a/devtools/client/performance/views/details-memory-flamegraph.js
+++ b/devtools/client/performance/views/details-memory-flamegraph.js
@@ -23,32 +23,32 @@ var MemoryFlameGraphView = extend(DetailsSubview, {
   /**
    * Sets up the view with event binding.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     DetailsSubview.initialize.call(this);
 
     this.graph = new FlameGraph($("#memory-flamegraph-view"));
     this.graph.timelineTickUnits = L10N.getStr("graphs.ms");
     this.graph.setTheme(PerformanceController.getTheme());
-    await this.graph.ready();
+    yield this.graph.ready();
 
     this._onRangeChangeInGraph = this._onRangeChangeInGraph.bind(this);
     this._onThemeChanged = this._onThemeChanged.bind(this);
 
     PerformanceController.on(EVENTS.THEME_CHANGED, this._onThemeChanged);
     this.graph.on("selecting", this._onRangeChangeInGraph);
-  },
+  }),
 
   /**
    * Unbinds events.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     DetailsSubview.destroy.call(this);
 
     PerformanceController.off(EVENTS.THEME_CHANGED, this._onThemeChanged);
     this.graph.off("selecting", this._onRangeChangeInGraph);
 
-    await this.graph.destroy();
-  },
+    yield this.graph.destroy();
+  }),
 
   /**
    * Method for handling all the set up for rendering a new flamegraph.
diff --git a/devtools/client/performance/views/details.js b/devtools/client/performance/views/details.js
index 51ee6935cd03..95557bc3682d 100644
--- a/devtools/client/performance/views/details.js
+++ b/devtools/client/performance/views/details.js
@@ -46,7 +46,7 @@ var DetailsView = {
   /**
    * Sets up the view with event binding, initializes subviews.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     this.el = $("#details-pane");
     this.toolbar = $("#performance-toolbar-controls-detail-views");
 
@@ -58,25 +58,25 @@ var DetailsView = {
       button.addEventListener("command", this._onViewToggle);
     }
 
-    await this.setAvailableViews();
+    yield this.setAvailableViews();
 
     PerformanceController.on(EVENTS.RECORDING_STATE_CHANGE,
                              this._onRecordingStoppedOrSelected);
     PerformanceController.on(EVENTS.RECORDING_SELECTED,
                              this._onRecordingStoppedOrSelected);
     PerformanceController.on(EVENTS.PREF_CHANGED, this.setAvailableViews);
-  },
+  }),
 
   /**
    * Unbinds events, destroys subviews.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     for (let button of $$("toolbarbutton[data-view]", this.toolbar)) {
       button.removeEventListener("command", this._onViewToggle);
     }
 
     for (let component of Object.values(this.components)) {
-      component.initialized && (await component.view.destroy());
+      component.initialized && (yield component.view.destroy());
     }
 
     PerformanceController.off(EVENTS.RECORDING_STATE_CHANGE,
@@ -84,7 +84,7 @@ var DetailsView = {
     PerformanceController.off(EVENTS.RECORDING_SELECTED,
                               this._onRecordingStoppedOrSelected);
     PerformanceController.off(EVENTS.PREF_CHANGED, this.setAvailableViews);
-  },
+  }),
 
   /**
    * Sets the possible views based off of recording features and server actor support
@@ -92,7 +92,7 @@ var DetailsView = {
    * if currently selected. Called when a preference changes in
    * `devtools.performance.ui.`.
    */
-  async setAvailableViews() {
+  setAvailableViews: Task.async(function* () {
     let recording = PerformanceController.getCurrentRecording();
     let isCompleted = recording && recording.isCompleted();
     let invalidCurrentView = false;
@@ -119,9 +119,9 @@ var DetailsView = {
     // use a default now that we have the recording configurations
     if ((this._initialized && isCompleted && invalidCurrentView) ||
         (!this._initialized && isCompleted && recording)) {
-      await this.selectDefaultView();
+      yield this.selectDefaultView();
     }
-  },
+  }),
 
   /**
    * Takes a view name and determines if the current recording
@@ -151,11 +151,11 @@ var DetailsView = {
    * @param String viewName
    *        Name of the view to be shown.
    */
-  async selectView(viewName) {
+  selectView: Task.async(function* (viewName) {
     let component = this.components[viewName];
     this.el.selectedPanel = $("#" + component.id);
 
-    await this._whenViewInitialized(component);
+    yield this._whenViewInitialized(component);
 
     for (let button of $$("toolbarbutton[data-view]", this.toolbar)) {
       if (button.getAttribute("data-view") === viewName) {
@@ -170,7 +170,7 @@ var DetailsView = {
     this._initialized = true;
 
     this.emit(EVENTS.UI_DETAILS_VIEW_SELECTED, viewName);
-  },
+  }),
 
   /**
    * Selects a default view based off of protocol support
@@ -220,12 +220,12 @@ var DetailsView = {
    * @param object component
    *        A component descriptor from DetailsView.components
    */
-  async _whenViewInitialized(component) {
+  _whenViewInitialized: Task.async(function* (component) {
     if (component.initialized) {
       return;
     }
     component.initialized = true;
-    await component.view.initialize();
+    yield component.view.initialize();
 
     // If this view is initialized *after* a recording is shown, it won't display
     // any data. Make sure it's populated by setting `shouldUpdateWhenShown`.
@@ -235,7 +235,7 @@ var DetailsView = {
     if (recording && recording.isCompleted()) {
       component.view.shouldUpdateWhenShown = true;
     }
-  },
+  }),
 
   /**
    * Called when recording stops or is selected.
diff --git a/devtools/client/performance/views/overview.js b/devtools/client/performance/views/overview.js
index a40eee138859..f45a6d844541 100644
--- a/devtools/client/performance/views/overview.js
+++ b/devtools/client/performance/views/overview.js
@@ -77,7 +77,7 @@ var OverviewView = {
   /**
    * Unbinds events.
    */
-  async destroy() {
+  destroy: Task.async(function* () {
     PerformanceController.off(EVENTS.PREF_CHANGED, this._onPrefChanged);
     PerformanceController.off(EVENTS.THEME_CHANGED, this._onThemeChanged);
     PerformanceController.off(EVENTS.RECORDING_STATE_CHANGE,
@@ -85,8 +85,8 @@ var OverviewView = {
     PerformanceController.off(EVENTS.RECORDING_SELECTED, this._onRecordingSelected);
     this.graphs.off("selecting", this._onGraphSelecting);
     this.graphs.off("rendered", this._onGraphRendered);
-    await this.graphs.destroy();
-  },
+    yield this.graphs.destroy();
+  }),
 
   /**
    * Returns true if any of the overview graphs have mouse dragging active,
@@ -173,27 +173,27 @@ var OverviewView = {
    * @param number resolution
    *        The fps graph resolution. @see Graphs.js
    */
-  async render(resolution) {
+  render: Task.async(function* (resolution) {
     if (this.isDisabled()) {
       return;
     }
 
     let recording = PerformanceController.getCurrentRecording();
-    await this.graphs.render(recording.getAllData(), resolution);
+    yield this.graphs.render(recording.getAllData(), resolution);
 
     // Finished rendering all graphs in this overview.
     this.emit(EVENTS.UI_OVERVIEW_RENDERED, resolution);
-  },
+  }),
 
   /**
    * Called at most every OVERVIEW_UPDATE_INTERVAL milliseconds
    * and uses data fetched from the controller to render
    * data into all the corresponding overview graphs.
    */
-  async _onRecordingTick() {
-    await this.render(FRAMERATE_GRAPH_LOW_RES_INTERVAL);
+  _onRecordingTick: Task.async(function* () {
+    yield this.render(FRAMERATE_GRAPH_LOW_RES_INTERVAL);
     this._prepareNextTick();
-  },
+  }),
 
   /**
    * Called to refresh the timer to keep firing _onRecordingTick.
@@ -209,8 +209,8 @@ var OverviewView = {
   /**
    * Called when recording state changes.
    */
-  _onRecordingStateChange:
-    OverviewViewOnStateChange(async function (_, state, recording) {
+  _onRecordingStateChange: OverviewViewOnStateChange(Task.async(
+    function* (_, state, recording) {
       if (state !== "recording-stopped") {
         return;
       }
@@ -223,22 +223,22 @@ var OverviewView = {
         return;
       }
       this.render(FRAMERATE_GRAPH_HIGH_RES_INTERVAL);
-      await this._checkSelection(recording);
-    }),
+      yield this._checkSelection(recording);
+    })),
 
   /**
    * Called when a new recording is selected.
    */
-  _onRecordingSelected: OverviewViewOnStateChange(async function (_, recording) {
+  _onRecordingSelected: OverviewViewOnStateChange(Task.async(function* (_, recording) {
     this._setGraphVisibilityFromRecordingFeatures(recording);
 
     // If this recording is complete, render the high res graph
     if (recording.isCompleted()) {
-      await this.render(FRAMERATE_GRAPH_HIGH_RES_INTERVAL);
+      yield this.render(FRAMERATE_GRAPH_HIGH_RES_INTERVAL);
     }
-    await this._checkSelection(recording);
+    yield this._checkSelection(recording);
     this.graphs.dropSelection();
-  }),
+  })),
 
   /**
    * Start the polling for rendering the overview graph.
@@ -266,10 +266,10 @@ var OverviewView = {
    * Makes sure the selection is enabled or disabled in all the graphs,
    * based on whether a recording currently exists and is not in progress.
    */
-  async _checkSelection(recording) {
+  _checkSelection: Task.async(function* (recording) {
     let isEnabled = recording ? recording.isCompleted() : false;
-    await this.graphs.selectionEnabled(isEnabled);
-  },
+    yield this.graphs.selectionEnabled(isEnabled);
+  }),
 
   /**
    * Fired when the graph selection has changed. Called by
@@ -303,10 +303,10 @@ var OverviewView = {
    * because those will set values on a recording model, and
    * the graphs will render based on the existence.
    */
-  async _onPrefChanged(_, prefName, prefValue) {
+  _onPrefChanged: Task.async(function* (_, prefName, prefValue) {
     switch (prefName) {
       case "hidden-markers": {
-        let graph = await this.graphs.isAvailable("timeline");
+        let graph = yield this.graphs.isAvailable("timeline");
         if (graph) {
           let filter = PerformanceController.getPref("hidden-markers");
           graph.setFilter(filter);
@@ -315,7 +315,7 @@ var OverviewView = {
         break;
       }
     }
-  },
+  }),
 
   _setGraphVisibilityFromRecordingFeatures: function (recording) {
     for (let [graphName, requirements] of Object.entries(GRAPH_REQUIREMENTS)) {
diff --git a/devtools/client/performance/views/recordings.js b/devtools/client/performance/views/recordings.js
index 7242522fcbe5..487ea4f037cc 100644
--- a/devtools/client/performance/views/recordings.js
+++ b/devtools/client/performance/views/recordings.js
@@ -161,11 +161,11 @@ var RecordingsView = {
   /**
    * The select listener for this container.
    */
-  async _onSelect(recording) {
+  _onSelect: Task.async(function* (recording) {
     this._listState.selected = recording;
     this.emit(EVENTS.UI_RECORDING_SELECTED, recording);
     this._renderList();
-  },
+  }),
 
   /**
    * The click listener for the "save" button of each item in this container.
diff --git a/devtools/client/performance/views/toolbar.js b/devtools/client/performance/views/toolbar.js
index 0784d79432da..3636add166d1 100644
--- a/devtools/client/performance/views/toolbar.js
+++ b/devtools/client/performance/views/toolbar.js
@@ -13,7 +13,7 @@ var ToolbarView = {
   /**
    * Sets up the view with event binding.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     this._onFilterPopupShowing = this._onFilterPopupShowing.bind(this);
     this._onFilterPopupHiding = this._onFilterPopupHiding.bind(this);
     this._onHiddenMarkersChanged = this._onHiddenMarkersChanged.bind(this);
@@ -30,7 +30,7 @@ var ToolbarView = {
     let experimentalEnabled = PerformanceController.getOption("experimental");
     this._toggleExperimentalUI(experimentalEnabled);
 
-    await this.optionsView.initialize();
+    yield this.optionsView.initialize();
     this.optionsView.on("pref-changed", this._onPrefChanged);
 
     this._buildMarkersFilterPopup();
@@ -39,7 +39,7 @@ var ToolbarView = {
                                                         this._onFilterPopupShowing);
     $("#performance-filter-menupopup").addEventListener("popuphiding",
                                                         this._onFilterPopupHiding);
-  },
+  }),
 
   /**
    * Unbinds events and cleans up view.
diff --git a/devtools/client/scratchpad/test/browser_scratchpad_autocomplete.js b/devtools/client/scratchpad/test/browser_scratchpad_autocomplete.js
index 88a7e57972b1..3a6eef8b44ac 100644
--- a/devtools/client/scratchpad/test/browser_scratchpad_autocomplete.js
+++ b/devtools/client/scratchpad/test/browser_scratchpad_autocomplete.js
@@ -6,6 +6,7 @@
 // Test the completions using numbers.
 const source = "0x1.";
 const completions = ["toExponential", "toFixed", "toString"];
+const { Task } = require("devtools/shared/task");
 
 function test() {
   const options = { tabContent: "test scratchpad autocomplete" };
@@ -15,14 +16,14 @@ function test() {
 }
 
 
-async function runTests([win, sp]) {
+function* runTests([win, sp]) {
   const {editor} = sp;
   const editorWin = editor.container.contentWindow;
 
   // Show the completions popup.
   sp.setText(source);
   sp.editor.setCursor({ line: 0, ch: source.length });
-  await keyOnce("suggestion-entered", " ", { ctrlKey: true });
+  yield keyOnce("suggestion-entered", " ", { ctrlKey: true });
 
   // Get the hints popup container.
   const hints = editorWin.document.querySelector(".CodeMirror-hints");
@@ -37,18 +38,18 @@ async function runTests([win, sp]) {
     let active = hints.querySelector(".CodeMirror-hint-active");
     is(active.textContent, completion,
        "Check that completion " + i++ + " is what is expected.");
-    await keyOnce("suggestion-entered", "VK_DOWN");
+    yield keyOnce("suggestion-entered", "VK_DOWN");
   }
 
   // We should have looped around to the first suggestion again. Accept it.
-  await keyOnce("after-suggest", "VK_RETURN");
+  yield keyOnce("after-suggest", "VK_RETURN");
 
   is(sp.getText(), source + completions[0],
      "Autocompletion should work and select the right element.");
 
   // Check that the information tooltips work.
   sp.setText("5");
-  await keyOnce("show-information", " ", { ctrlKey: true, shiftKey: true });
+  yield keyOnce("show-information", " ", { ctrlKey: true, shiftKey: true });
 
   // Get the information container.
   const info = editorWin.document.querySelector(".CodeMirror-Tern-information");
diff --git a/devtools/client/scratchpad/test/browser_scratchpad_close_toolbox.js b/devtools/client/scratchpad/test/browser_scratchpad_close_toolbox.js
index 1057380e82a4..fd1126fd42af 100644
--- a/devtools/client/scratchpad/test/browser_scratchpad_close_toolbox.js
+++ b/devtools/client/scratchpad/test/browser_scratchpad_close_toolbox.js
@@ -4,6 +4,7 @@
 // Test that closing the toolbox after having opened a scratchpad leaves the
 // latter in a functioning state.
 
+var {Task} = require("devtools/shared/task");
 var {TargetFactory} = require("devtools/client/framework/target");
 
 function test() {
@@ -15,23 +16,23 @@ function test() {
     .then(finish, console.error);
 }
 
-async function runTests([win, sp]) {
+function* runTests([win, sp]) {
   // Use the scratchpad before opening the toolbox.
   const source = "window.foobar = 7;";
   sp.setText(source);
-  let [,, result] = await sp.display();
+  let [,, result] = yield sp.display();
   is(result, 7, "Display produced the expected output.");
 
   // Now open the toolbox and close it again.
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "webconsole");
+  let toolbox = yield gDevTools.showToolbox(target, "webconsole");
   ok(toolbox, "Toolbox was opened.");
-  let closed = await gDevTools.closeToolbox(target);
+  let closed = yield gDevTools.closeToolbox(target);
   is(closed, true, "Toolbox was closed.");
 
   // Now see if using the scratcphad works as expected.
   sp.setText(source);
-  let [,, result2] = await sp.display();
+  let [,, result2] = yield sp.display();
   is(result2, 7,
      "Display produced the expected output after the toolbox was gone.");
 }
diff --git a/devtools/client/scratchpad/test/browser_scratchpad_contexts.js b/devtools/client/scratchpad/test/browser_scratchpad_contexts.js
index 687eb7b5c870..adb23b29f86d 100644
--- a/devtools/client/scratchpad/test/browser_scratchpad_contexts.js
+++ b/devtools/client/scratchpad/test/browser_scratchpad_contexts.js
@@ -26,7 +26,7 @@ function runTests() {
 
   let tests = [{
     method: "run",
-    prepare: async function () {
+    prepare: function* () {
       sp.setContentContext();
 
       is(sp.executionContext, gScratchpadWindow.SCRATCHPAD_CONTEXT_CONTENT,
@@ -43,18 +43,18 @@ function runTests() {
 
       sp.editor.setText("window.foobarBug636725 = 'aloha';");
 
-      let pageResult = await inContent(function() {
+      let pageResult = yield inContent(function* () {
         return content.wrappedJSObject.foobarBug636725;
       });
       ok(!pageResult, "no content.foobarBug636725");
     },
-    then: function() {
+    then: function* () {
       is(gBrowser.contentWindowAsCPOW.wrappedJSObject.foobarBug636725, "aloha",
          "content.foobarBug636725 has been set");
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       sp.setBrowserContext();
 
       is(sp.executionContext, gScratchpadWindow.SCRATCHPAD_CONTEXT_BROWSER,
@@ -75,7 +75,7 @@ function runTests() {
       is(sp.getText(), "window.foobarBug636725 = 'aloha2';",
          "setText() worked");
     },
-    then: function() {
+    then: function* () {
       is(window.foobarBug636725, "aloha2",
          "window.foobarBug636725 has been set");
 
@@ -84,48 +84,48 @@ function runTests() {
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       sp.editor.replaceText("gBrowser", sp.editor.getPosition(7));
 
       is(sp.getText(), "window.gBrowser",
          "setText() worked with no end for the replace range");
     },
-    then: function([, , result]) {
+    then: function* ([, , result]) {
       is(result.class, "Object",
          "chrome context has access to chrome objects");
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       // Check that the sandbox is cached.
       sp.editor.setText("typeof foobarBug636725cache;");
     },
-    then: function([, , result]) {
+    then: function* ([, , result]) {
       is(result, "undefined", "global variable does not exist");
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       sp.editor.setText("window.foobarBug636725cache = 'foo';" +
                  "typeof foobarBug636725cache;");
     },
-    then: function([, , result]) {
+    then: function* ([, , result]) {
       is(result, "string",
          "global variable exists across two different executions");
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       sp.editor.setText("window.foobarBug636725cache2 = 'foo';" +
                  "typeof foobarBug636725cache2;");
     },
-    then: function([, , result]) {
+    then: function* ([, , result]) {
       is(result, "string",
          "global variable exists across two different executions");
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       sp.setContentContext();
 
       is(sp.executionContext, gScratchpadWindow.SCRATCHPAD_CONTEXT_CONTENT,
@@ -133,7 +133,7 @@ function runTests() {
 
       sp.editor.setText("typeof foobarBug636725cache2;");
     },
-    then: function([, , result]) {
+    then: function* ([, , result]) {
       is(result, "undefined",
          "global variable no longer exists after changing the context");
     }
diff --git a/devtools/client/scratchpad/test/browser_scratchpad_disable_view_menu_items.js b/devtools/client/scratchpad/test/browser_scratchpad_disable_view_menu_items.js
index ec337bbfb7d7..ed501ce2d64f 100644
--- a/devtools/client/scratchpad/test/browser_scratchpad_disable_view_menu_items.js
+++ b/devtools/client/scratchpad/test/browser_scratchpad_disable_view_menu_items.js
@@ -4,6 +4,7 @@
 // Test if the view menu items "Larger Font" and "Smaller Font" are disabled
 // when the font size reaches the maximum/minimum values.
 
+var {Task} = require("devtools/shared/task");
 
 function test() {
   const options = {
@@ -14,17 +15,17 @@ function test() {
     .then(finish, console.error);
 }
 
-async function runTests([win, sp]) {
-  await testMaximumFontSize(win, sp);
+function* runTests([win, sp]) {
+  yield testMaximumFontSize(win, sp);
 
-  await testMinimumFontSize(win, sp);
+  yield testMinimumFontSize(win, sp);
 }
 
 const MAXIMUM_FONT_SIZE = 96;
 const MINIMUM_FONT_SIZE = 6;
 const NORMAL_FONT_SIZE = 12;
 
-var testMaximumFontSize = async function (win, sp) {
+var testMaximumFontSize = Task.async(function* (win, sp) {
   let doc = win.document;
 
   Services.prefs.clearUserPref("devtools.scratchpad.editorFontSize");
@@ -42,9 +43,9 @@ var testMaximumFontSize = async function (win, sp) {
   menu.doCommand();
 
   ok(cmd.hasAttribute("disabled") === false, 'Command "sp-cmd-larger-font" is enabled.');
-};
+});
 
-var testMinimumFontSize = async function (win, sp) {
+var testMinimumFontSize = Task.async(function* (win, sp) {
   let doc = win.document;
 
   let menu = doc.getElementById("sp-menu-smaller-font");
@@ -62,4 +63,4 @@ var testMinimumFontSize = async function (win, sp) {
   ok(cmd.hasAttribute("disabled") === false, 'Command "sp-cmd-smaller-font" is enabled.');
 
   Services.prefs.clearUserPref("devtools.scratchpad.editorFontSize");
-};
+});
diff --git a/devtools/client/scratchpad/test/browser_scratchpad_execute_print.js b/devtools/client/scratchpad/test/browser_scratchpad_execute_print.js
index b31971e67199..804cea16f234 100644
--- a/devtools/client/scratchpad/test/browser_scratchpad_execute_print.js
+++ b/devtools/client/scratchpad/test/browser_scratchpad_execute_print.js
@@ -18,16 +18,16 @@ function runTests() {
   let sp = gScratchpadWindow.Scratchpad;
   let tests = [{
     method: "run",
-    prepare: async function () {
-      await inContent(function() {
+    prepare: function* () {
+      yield inContent(function* () {
         content.wrappedJSObject.foobarBug636725 = 1;
       });
       sp.editor.setText("++window.foobarBug636725");
     },
-    then: async function ([code, , result]) {
+    then: function* ([code, , result]) {
       is(code, sp.getText(), "code is correct");
 
-      let pageResult = await inContent(function() {
+      let pageResult = yield inContent(function* () {
         return content.wrappedJSObject.foobarBug636725;
       });
       is(result, pageResult,
@@ -40,9 +40,9 @@ function runTests() {
     }
   }, {
     method: "display",
-    prepare: function() {},
-    then: async function () {
-      let pageResult = await inContent(function() {
+    prepare: function* () {},
+    then: function* () {
+      let pageResult = yield inContent(function* () {
         return content.wrappedJSObject.foobarBug636725;
       });
       is(pageResult, 3, "display() updated window.foobarBug636725");
@@ -54,12 +54,12 @@ function runTests() {
     }
   }, {
     method: "run",
-    prepare: function() {
+    prepare: function* () {
       sp.editor.setText("window.foobarBug636725 = 'a';\n" +
         "window.foobarBug636725 = 'b';");
       sp.editor.setSelection({ line: 0, ch: 0 }, { line: 0, ch: 29 });
     },
-    then: async function ([code, , result]) {
+    then: function* ([code, , result]) {
       is(code, "window.foobarBug636725 = 'a';", "code is correct");
       is(result, "a", "result is correct");
 
@@ -67,20 +67,20 @@ function runTests() {
                        "window.foobarBug636725 = 'b';",
          "run() does not change the textbox value");
 
-      let pageResult = await inContent(function() {
+      let pageResult = yield inContent(function* () {
         return content.wrappedJSObject.foobarBug636725;
       });
       is(pageResult, "a", "run() worked for the selected range");
     }
   }, {
     method: "display",
-    prepare: function() {
+    prepare: function* () {
       sp.editor.setText("window.foobarBug636725 = 'c';\n" +
                  "window.foobarBug636725 = 'b';");
       sp.editor.setSelection({ line: 0, ch: 0 }, { line: 0, ch: 22 });
     },
-    then: async function () {
-      let pageResult = await inContent(function() {
+    then: function* () {
+      let pageResult = yield inContent(function* () {
         return content.wrappedJSObject.foobarBug636725;
       });
       is(pageResult, "a", "display() worked for the selected range");
diff --git a/devtools/client/scratchpad/test/browser_scratchpad_inspect_primitives.js b/devtools/client/scratchpad/test/browser_scratchpad_inspect_primitives.js
index a19cae413251..914f0a6d8919 100644
--- a/devtools/client/scratchpad/test/browser_scratchpad_inspect_primitives.js
+++ b/devtools/client/scratchpad/test/browser_scratchpad_inspect_primitives.js
@@ -4,6 +4,7 @@
 // Test that inspecting primitive values uses the object inspector, not an
 // inline comment.
 
+var {Task} = require("devtools/shared/task");
 
 function test() {
   const options = {
@@ -14,26 +15,26 @@ function test() {
     .then(finish, console.error);
 }
 
-async function runTests([win, sp]) {
+function* runTests([win, sp]) {
   // Inspect a number.
-  await checkResults(sp, 7);
+  yield checkResults(sp, 7);
 
   // Inspect a string.
-  await checkResults(sp, "foobar", true);
+  yield checkResults(sp, "foobar", true);
 
   // Inspect a boolean.
-  await checkResults(sp, true);
+  yield checkResults(sp, true);
 }
 
 // Helper function that does the actual testing.
-var checkResults = async function (sp, value, isString = false) {
+var checkResults = Task.async(function* (sp, value, isString = false) {
   let sourceValue = value;
   if (isString) {
     sourceValue = '"' + value + '"';
   }
   let source = "var foobar = " + sourceValue + "; foobar";
   sp.setText(source);
-  await sp.inspect();
+  yield sp.inspect();
 
   let sidebar = sp.sidebar;
   ok(sidebar.visible, "sidebar is open");
@@ -57,4 +58,4 @@ var checkResults = async function (sp, value, isString = false) {
   ok(!tabbox.hasAttribute("hidden"), "Scratchpad sidebar visible");
   sidebar.hide();
   ok(tabbox.hasAttribute("hidden"), "Scratchpad sidebar hidden");
-};
+});
diff --git a/devtools/client/scratchpad/test/head.js b/devtools/client/scratchpad/test/head.js
index d6bd525d0de8..f1e4d72a4822 100644
--- a/devtools/client/scratchpad/test/head.js
+++ b/devtools/client/scratchpad/test/head.js
@@ -192,13 +192,13 @@ function runAsyncTests(aScratchpad, aTests)
  * @return Promise
  *         The promise that will be resolved when all tests are finished.
  */
-var runAsyncCallbackTests = async function (aScratchpad, aTests) {
+var runAsyncCallbackTests = Task.async(function* (aScratchpad, aTests) {
   for (let {prepare, method, then} of aTests) {
-    await prepare();
-    let res = await aScratchpad[method]();
-    await then(res);
+    yield prepare();
+    let res = yield aScratchpad[method]();
+    yield then(res);
   }
-};
+});
 
 /**
  * A simple wrapper for ContentTask.spawn for more compact code.
diff --git a/devtools/client/shadereditor/shadereditor.js b/devtools/client/shadereditor/shadereditor.js
index 46f351bbde52..0ab1e5ff051e 100644
--- a/devtools/client/shadereditor/shadereditor.js
+++ b/devtools/client/shadereditor/shadereditor.js
@@ -8,7 +8,6 @@ const {XPCOMUtils} = require("resource://gre/modules/XPCOMUtils.jsm");
 const {SideMenuWidget} = require("resource://devtools/client/shared/widgets/SideMenuWidget.jsm");
 const promise = require("promise");
 const defer = require("devtools/shared/defer");
-const {Task} = require("devtools/shared/task");
 const Services = require("Services");
 const EventEmitter = require("devtools/shared/old-event-emitter");
 const Tooltip = require("devtools/client/shared/widgets/tooltip/Tooltip");
@@ -17,6 +16,7 @@ const {LocalizationHelper} = require("devtools/shared/l10n");
 const {extend} = require("devtools/shared/extend");
 const {WidgetMethods, setNamedTimeout} =
   require("devtools/client/shared/widgets/view-helpers");
+const {Task} = require("devtools/shared/task");
 
 // Use privileged promise in panel documents to prevent having them to freeze
 // during toolbox destruction. See bug 1402779.
@@ -405,14 +405,14 @@ var ShadersEditorsView = {
       editor.clearHistory();
     }
 
-    return (async function () {
-      await view._toggleListeners("off");
-      await promise.all([
+    return Task.spawn(function* () {
+      yield view._toggleListeners("off");
+      yield promise.all([
         view._getEditor("vs").then(e => setTextAndClearHistory(e, sources.vs)),
         view._getEditor("fs").then(e => setTextAndClearHistory(e, sources.fs))
       ]);
-      await view._toggleListeners("on");
-    })().then(() => window.emit(EVENTS.SOURCES_SHOWN, sources));
+      yield view._toggleListeners("on");
+    }).then(() => window.emit(EVENTS.SOURCES_SHOWN, sources));
   },
 
   /**
@@ -498,17 +498,17 @@ var ShadersEditorsView = {
    *        The corresponding shader type for the focused editor (e.g. "vs").
    */
   _doCompile: function (type) {
-    (async function () {
-      let editor = await this._getEditor(type);
-      let shaderActor = await ShadersListView.selectedAttachment[type];
+    Task.spawn(function* () {
+      let editor = yield this._getEditor(type);
+      let shaderActor = yield ShadersListView.selectedAttachment[type];
 
       try {
-        await shaderActor.compile(editor.getText());
+        yield shaderActor.compile(editor.getText());
         this._onSuccessfulCompilation();
       } catch (e) {
         this._onFailedCompilation(type, editor, e);
       }
-    }.bind(this))();
+    }.bind(this));
   },
 
   /**
diff --git a/devtools/client/shadereditor/test/browser_se_aaa_run_first_leaktest.js b/devtools/client/shadereditor/test/browser_se_aaa_run_first_leaktest.js
index c5b101aaec0a..6efe510913ec 100644
--- a/devtools/client/shadereditor/test/browser_se_aaa_run_first_leaktest.js
+++ b/devtools/client/shadereditor/test/browser_se_aaa_run_first_leaktest.js
@@ -6,12 +6,12 @@
  * You can also use this initialization format as a template for other tests.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
 
   ok(target, "Should have a target available.");
   ok(panel, "Should have a panel available.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_bfcache.js b/devtools/client/shadereditor/test/browser_se_bfcache.js
index e5f8a9e113c8..2b568e3fe643 100644
--- a/devtools/client/shadereditor/test/browser_se_bfcache.js
+++ b/devtools/client/shadereditor/test/browser_se_bfcache.js
@@ -4,8 +4,8 @@
 /**
  * Tests if the shader editor works with bfcache.
  */
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, $, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   // Attach frame scripts if in e10s to perform
@@ -13,19 +13,19 @@ async function ifWebGLSupported() {
   loadFrameScripts();
 
   let reloaded = reload(target);
-  let firstProgram = await once(gFront, "program-linked");
-  await reloaded;
+  let firstProgram = yield once(gFront, "program-linked");
+  yield reloaded;
 
   let navigated = navigate(target, MULTIPLE_CONTEXTS_URL);
-  let [secondProgram, thirdProgram] = await getPrograms(gFront, 2);
-  await navigated;
+  let [secondProgram, thirdProgram] = yield getPrograms(gFront, 2);
+  yield navigated;
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
-  await navigateInHistory(target, "back", "will-navigate");
-  await once(panel.panelWin, EVENTS.PROGRAMS_ADDED);
-  await once(panel.panelWin, EVENTS.SOURCES_SHOWN);
+  yield navigateInHistory(target, "back", "will-navigate");
+  yield once(panel.panelWin, EVENTS.PROGRAMS_ADDED);
+  yield once(panel.panelWin, EVENTS.SOURCES_SHOWN);
 
   is($("#content").hidden, false,
     "The tool's content should not be hidden.");
@@ -39,9 +39,9 @@ async function ifWebGLSupported() {
   is(fsEditor.getText().indexOf("gl_FragColor"), 97,
     "The fragment shader editor contains the correct text.");
 
-  await navigateInHistory(target, "forward", "will-navigate");
-  await once(panel.panelWin, EVENTS.PROGRAMS_ADDED);
-  await once(panel.panelWin, EVENTS.SOURCES_SHOWN);
+  yield navigateInHistory(target, "forward", "will-navigate");
+  yield once(panel.panelWin, EVENTS.PROGRAMS_ADDED);
+  yield once(panel.panelWin, EVENTS.SOURCES_SHOWN);
 
   is($("#content").hidden, false,
     "The tool's content should not be hidden.");
@@ -55,6 +55,6 @@ async function ifWebGLSupported() {
   is(fsEditor.getText().indexOf("gl_FragColor"), 89,
     "The fragment shader editor contains the correct text.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_editors-contents.js b/devtools/client/shadereditor/test/browser_se_editors-contents.js
index e0a9d8ca7564..fdf2612ed9ef 100644
--- a/devtools/client/shadereditor/test/browser_se_editors-contents.js
+++ b/devtools/client/shadereditor/test/browser_se_editors-contents.js
@@ -6,18 +6,18 @@
  * becomes available.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, ShadersEditorsView, EVENTS } = panel.panelWin;
 
   reload(target);
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
 
   is(vsEditor.getText().indexOf("gl_Position"), 170,
@@ -25,6 +25,6 @@ async function ifWebGLSupported() {
   is(fsEditor.getText().indexOf("gl_FragColor"), 97,
     "The fragment shader editor contains the correct text.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_editors-error-gutter.js b/devtools/client/shadereditor/test/browser_se_editors-error-gutter.js
index 1d113622c7d5..686fb120a5c7 100644
--- a/devtools/client/shadereditor/test/browser_se_editors-error-gutter.js
+++ b/devtools/client/shadereditor/test/browser_se_editors-error-gutter.js
@@ -6,72 +6,72 @@
  * when there's a shader compilation error.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, EVENTS, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   vsEditor.replaceText("vec3", { line: 7, ch: 22 }, { line: 7, ch: 26 });
-  let [, vertError] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  let [, vertError] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   checkHasVertFirstError(true, vertError);
   checkHasVertSecondError(false, vertError);
   info("Error marks added in the vertex shader editor.");
 
   vsEditor.insertText(" ", { line: 1, ch: 0 });
-  await once(panel.panelWin, EVENTS.EDITOR_ERROR_MARKERS_REMOVED);
+  yield once(panel.panelWin, EVENTS.EDITOR_ERROR_MARKERS_REMOVED);
   is(vsEditor.getText(1), "       precision lowp float;", "Typed space.");
   checkHasVertFirstError(false, vertError);
   checkHasVertSecondError(false, vertError);
   info("Error marks removed while typing in the vertex shader editor.");
 
-  [, vertError] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  [, vertError] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   checkHasVertFirstError(true, vertError);
   checkHasVertSecondError(false, vertError);
   info("Error marks were re-added after recompiling the vertex shader.");
 
   fsEditor.replaceText("vec4", { line: 2, ch: 14 }, { line: 2, ch: 18 });
-  let [, fragError] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  let [, fragError] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   checkHasVertFirstError(true, vertError);
   checkHasVertSecondError(false, vertError);
   checkHasFragError(true, fragError);
   info("Error marks added in the fragment shader editor.");
 
   fsEditor.insertText(" ", { line: 1, ch: 0 });
-  await once(panel.panelWin, EVENTS.EDITOR_ERROR_MARKERS_REMOVED);
+  yield once(panel.panelWin, EVENTS.EDITOR_ERROR_MARKERS_REMOVED);
   is(fsEditor.getText(1), "       precision lowp float;", "Typed space.");
   checkHasVertFirstError(true, vertError);
   checkHasVertSecondError(false, vertError);
   checkHasFragError(false, fragError);
   info("Error marks removed while typing in the fragment shader editor.");
 
-  [, fragError] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  [, fragError] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   checkHasVertFirstError(true, vertError);
   checkHasVertSecondError(false, vertError);
   checkHasFragError(true, fragError);
   info("Error marks were re-added after recompiling the fragment shader.");
 
   vsEditor.replaceText("2", { line: 3, ch: 19 }, { line: 3, ch: 20 });
-  await once(panel.panelWin, EVENTS.EDITOR_ERROR_MARKERS_REMOVED);
+  yield once(panel.panelWin, EVENTS.EDITOR_ERROR_MARKERS_REMOVED);
   checkHasVertFirstError(false, vertError);
   checkHasVertSecondError(false, vertError);
   checkHasFragError(true, fragError);
   info("Error marks removed while typing in the vertex shader editor again.");
 
-  [, vertError] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  [, vertError] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   checkHasVertFirstError(true, vertError);
   checkHasVertSecondError(true, vertError);
   checkHasFragError(true, fragError);
   info("Error marks were re-added after recompiling the fragment shader again.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 
   function checkHasVertFirstError(bool, error) {
diff --git a/devtools/client/shadereditor/test/browser_se_editors-error-tooltip.js b/devtools/client/shadereditor/test/browser_se_editors-error-tooltip.js
index 9a45e52fef35..d124d867b180 100644
--- a/devtools/client/shadereditor/test/browser_se_editors-error-tooltip.js
+++ b/devtools/client/shadereditor/test/browser_se_editors-error-tooltip.js
@@ -6,21 +6,21 @@
  * a shader compilation error.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, EVENTS, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   vsEditor.replaceText("vec3", { line: 7, ch: 22 }, { line: 7, ch: 26 });
-  await once(panel.panelWin, EVENTS.SHADER_COMPILED);
+  yield once(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   // Synthesizing 'mouseover' events doesn't work, hack around this by
   // manually calling the event listener with the expected arguments.
@@ -55,6 +55,6 @@ async function ifWebGLSupported() {
   ok(messages[2].textContent.includes("'assign' : cannot convert"),
     "The third message contains the correct text.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_editors-lazy-init.js b/devtools/client/shadereditor/test/browser_se_editors-lazy-init.js
index 5c64c2668f10..b2d9d888e827 100644
--- a/devtools/client/shadereditor/test/browser_se_editors-lazy-init.js
+++ b/devtools/client/shadereditor/test/browser_se_editors-lazy-init.js
@@ -5,15 +5,15 @@
  * Tests if source editors are lazily initialized.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  await once(gFront, "program-linked");
+  yield once(gFront, "program-linked");
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   ok(vsEditor, "A vertex shader editor was initialized.");
   ok(fsEditor, "A fragment shader editor was initialized.");
@@ -21,14 +21,14 @@ async function ifWebGLSupported() {
   isnot(vsEditor, fsEditor,
     "The vertex shader editor is distinct from the fragment shader editor.");
 
-  let vsEditor2 = await ShadersEditorsView._getEditor("vs");
-  let fsEditor2 = await ShadersEditorsView._getEditor("fs");
+  let vsEditor2 = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor2 = yield ShadersEditorsView._getEditor("fs");
 
   is(vsEditor, vsEditor2,
     "The vertex shader editor instances are cached.");
   is(fsEditor, fsEditor2,
     "The fragment shader editor instances are cached.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_first-run.js b/devtools/client/shadereditor/test/browser_se_first-run.js
index 3258e9cd15cf..33239bcbee99 100644
--- a/devtools/client/shadereditor/test/browser_se_first-run.js
+++ b/devtools/client/shadereditor/test/browser_se_first-run.js
@@ -5,8 +5,8 @@
  * Tests if the shader editor shows the appropriate UI when opened.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, $ } = panel.panelWin;
 
   is($("#reload-notice").hidden, false,
@@ -20,7 +20,7 @@ async function ifWebGLSupported() {
   let linked = once(gFront, "program-linked");
   reload(target);
 
-  await navigating;
+  yield navigating;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden when navigating.");
@@ -29,7 +29,7 @@ async function ifWebGLSupported() {
   is($("#content").hidden, true,
     "The tool's content should still be hidden.");
 
-  await linked;
+  yield linked;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden after linking.");
@@ -38,6 +38,6 @@ async function ifWebGLSupported() {
   is($("#content").hidden, false,
     "The tool's content should not be hidden anymore.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_navigation.js b/devtools/client/shadereditor/test/browser_se_navigation.js
index ccd0947f1453..f1adc3e76e3f 100644
--- a/devtools/client/shadereditor/test/browser_se_navigation.js
+++ b/devtools/client/shadereditor/test/browser_se_navigation.js
@@ -5,12 +5,12 @@
  * Tests target navigations are handled correctly in the UI.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, $, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
@@ -29,8 +29,8 @@ async function ifWebGLSupported() {
   is(ShadersListView.selectedIndex, 0,
     "The shaders list has a correct index selected.");
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   is(vsEditor.getText().indexOf("gl_Position"), 170,
     "The vertex shader editor contains the correct text.");
@@ -41,7 +41,7 @@ async function ifWebGLSupported() {
   let navigated = once(target, "will-navigate");
   navigate(target, "about:blank");
 
-  await promise.all([navigating, once(panel.panelWin, EVENTS.UI_RESET) ]);
+  yield promise.all([navigating, once(panel.panelWin, EVENTS.UI_RESET) ]);
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden while navigating.");
@@ -57,7 +57,7 @@ async function ifWebGLSupported() {
   is(ShadersListView.selectedIndex, -1,
     "The shaders list has a negative index.");
 
-  await navigated;
+  yield navigated;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should still be hidden after navigating.");
@@ -66,6 +66,6 @@ async function ifWebGLSupported() {
   is($("#content").hidden, true,
     "The tool's content should be still hidden since there's no WebGL content.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_programs-blackbox-01.js b/devtools/client/shadereditor/test/browser_se_programs-blackbox-01.js
index 59d3088093bf..b451365a450e 100644
--- a/devtools/client/shadereditor/test/browser_se_programs-blackbox-01.js
+++ b/devtools/client/shadereditor/test/browser_se_programs-blackbox-01.js
@@ -5,8 +5,8 @@
  * Tests if blackboxing a program works properly.
  */
 
-async function ifWebGLSupported() {
-  let { target, debuggee, panel } = await initShaderEditor(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, debuggee, panel } = yield initShaderEditor(MULTIPLE_CONTEXTS_URL);
   let { gFront, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   once(panel.panelWin, EVENTS.SHADER_COMPILED).then(() => {
@@ -14,13 +14,13 @@ async function ifWebGLSupported() {
   });
 
   reload(target);
-  let [[firstProgramActor, secondProgramActor]] = await promise.all([
+  let [[firstProgramActor, secondProgramActor]] = yield promise.all([
     getPrograms(gFront, 2),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   vsEditor.once("change", () => {
     ok(false, "The vertex shader source was unexpectedly changed.");
@@ -32,10 +32,10 @@ async function ifWebGLSupported() {
     ok(false, "No sources should be changed form this point onward.");
   });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
 
   ok(!ShadersListView.selectedAttachment.isBlackBoxed,
     "The first program should not be blackboxed yet.");
@@ -57,10 +57,10 @@ async function ifWebGLSupported() {
   is(getBlackBoxCheckbox(panel, 1).checked, true,
     "The second blackbox checkbox should still be checked.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The first program was correctly blackboxed.");
 
   getBlackBoxCheckbox(panel, 1).click();
@@ -74,35 +74,35 @@ async function ifWebGLSupported() {
   is(getBlackBoxCheckbox(panel, 1).checked, false,
     "The second blackbox checkbox should now be unchecked.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
   ok(true, "The second program was correctly blackboxed.");
 
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 0) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
   ok(true, "Highlighting shouldn't work while blackboxed (1).");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 0) });
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
   ok(true, "Highlighting shouldn't work while blackboxed (2).");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas2");
   ok(true, "Highlighting shouldn't work while blackboxed (3).");
 
   getBlackBoxCheckbox(panel, 0).click();
@@ -117,38 +117,38 @@ async function ifWebGLSupported() {
   is(getBlackBoxCheckbox(panel, 1).checked, true,
     "The second blackbox checkbox should now be rechecked.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two programs were correctly unblackboxed.");
 
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 0) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The first program was correctly highlighted.");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 0) });
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
   ok(true, "The second program was correctly highlighted.");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two programs were correctly unhighlighted.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/shadereditor/test/browser_se_programs-blackbox-02.js b/devtools/client/shadereditor/test/browser_se_programs-blackbox-02.js
index a7849d8961fe..391a272c8540 100644
--- a/devtools/client/shadereditor/test/browser_se_programs-blackbox-02.js
+++ b/devtools/client/shadereditor/test/browser_se_programs-blackbox-02.js
@@ -6,54 +6,54 @@
  * overlapping geometry.
  */
 
-async function ifWebGLSupported() {
-  let { target, debuggee, panel } = await initShaderEditor(BLENDED_GEOMETRY_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, debuggee, panel } = yield initShaderEditor(BLENDED_GEOMETRY_CANVAS_URL);
   let { gFront, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  let [[firstProgramActor, secondProgramActor]] = await promise.all([
+  let [[firstProgramActor, secondProgramActor]] = yield promise.all([
     getPrograms(gFront, 2),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
   ok(true, "The canvas was correctly drawn.");
 
   getBlackBoxCheckbox(panel, 0).click();
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 0, b: 0, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 0, b: 0, a: 127 }, true);
   ok(true, "The first program was correctly blackboxed.");
 
   getBlackBoxCheckbox(panel, 0).click();
   getBlackBoxCheckbox(panel, 1).click();
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 127, g: 127, b: 127, a: 255 }, true);
   ok(true, "The second program was correctly blackboxed.");
 
   getBlackBoxCheckbox(panel, 1).click();
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
   ok(true, "The two programs were correctly unblackboxed.");
 
   getBlackBoxCheckbox(panel, 0).click();
   getBlackBoxCheckbox(panel, 1).click();
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 0, b: 0, a: 255 }, true);
   ok(true, "The two programs were correctly blackboxed again.");
 
   getBlackBoxCheckbox(panel, 0).click();
   getBlackBoxCheckbox(panel, 1).click();
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
   ok(true, "The two programs were correctly unblackboxed again.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/shadereditor/test/browser_se_programs-cache.js b/devtools/client/shadereditor/test/browser_se_programs-cache.js
index c13ab5bf82da..5e5708e446a4 100644
--- a/devtools/client/shadereditor/test/browser_se_programs-cache.js
+++ b/devtools/client/shadereditor/test/browser_se_programs-cache.js
@@ -5,12 +5,12 @@
  * Tests that program and shader actors are cached in the frontend.
  */
 
-async function ifWebGLSupported() {
-  let { target, debuggee, panel } = await initShaderEditor(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, debuggee, panel } = yield initShaderEditor(MULTIPLE_CONTEXTS_URL);
   let { EVENTS, gFront, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  let [[programActor]] = await promise.all([
+  let [[programActor]] = yield promise.all([
     getPrograms(gFront, 1),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
@@ -20,22 +20,22 @@ async function ifWebGLSupported() {
   is(programItem.attachment.programActor, programActor,
     "The correct program actor is cached for the selected item.");
 
-  is((await programActor.getVertexShader()),
-     (await programItem.attachment.vs),
+  is((yield programActor.getVertexShader()),
+     (yield programItem.attachment.vs),
     "The cached vertex shader promise returns the correct actor.");
 
-  is((await programActor.getFragmentShader()),
-     (await programItem.attachment.fs),
+  is((yield programActor.getFragmentShader()),
+     (yield programItem.attachment.fs),
     "The cached fragment shader promise returns the correct actor.");
 
-  is((await (await programActor.getVertexShader()).getText()),
-     (await (await ShadersEditorsView._getEditor("vs")).getText()),
+  is((yield (yield programActor.getVertexShader()).getText()),
+     (yield (yield ShadersEditorsView._getEditor("vs")).getText()),
     "The cached vertex shader promise returns the correct text.");
 
-  is((await (await programActor.getFragmentShader()).getText()),
-     (await (await ShadersEditorsView._getEditor("fs")).getText()),
+  is((yield (yield programActor.getFragmentShader()).getText()),
+     (yield (yield ShadersEditorsView._getEditor("fs")).getText()),
     "The cached fragment shader promise returns the correct text.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_programs-highlight-01.js b/devtools/client/shadereditor/test/browser_se_programs-highlight-01.js
index 03b7e6da076f..863dc2672c6e 100644
--- a/devtools/client/shadereditor/test/browser_se_programs-highlight-01.js
+++ b/devtools/client/shadereditor/test/browser_se_programs-highlight-01.js
@@ -5,8 +5,8 @@
  * Tests if highlighting a program works properly.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(MULTIPLE_CONTEXTS_URL);
   let { gFront, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   once(panel.panelWin, EVENTS.SHADER_COMPILED).then(() => {
@@ -14,13 +14,13 @@ async function ifWebGLSupported() {
   });
 
   reload(target);
-  let [[firstProgramActor, secondProgramActor]] = await promise.all([
+  let [[firstProgramActor, secondProgramActor]] = yield promise.all([
     getPrograms(gFront, 2),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   vsEditor.once("change", () => {
     ok(false, "The vertex shader source was unexpectedly changed.");
@@ -32,53 +32,53 @@ async function ifWebGLSupported() {
     ok(false, "No sources should be changed form this point onward.");
   });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
 
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 0) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The first program was correctly highlighted.");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 0) });
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 64, a: 255 }, true, "#canvas2");
   ok(true, "The second program was correctly highlighted.");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two programs were correctly unhighlighted.");
 
   ShadersListView._onProgramMouseOver({ target: getBlackBoxCheckbox(panel, 0) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two programs were left unchanged after hovering a blackbox checkbox.");
 
   ShadersListView._onProgramMouseOut({ target: getBlackBoxCheckbox(panel, 0) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two programs were left unchanged after unhovering a blackbox checkbox.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/shadereditor/test/browser_se_programs-highlight-02.js b/devtools/client/shadereditor/test/browser_se_programs-highlight-02.js
index a1c9b6a3f3d4..c6cbd796b63a 100644
--- a/devtools/client/shadereditor/test/browser_se_programs-highlight-02.js
+++ b/devtools/client/shadereditor/test/browser_se_programs-highlight-02.js
@@ -6,40 +6,40 @@
  * overlapping geometry.
  */
 
-async function ifWebGLSupported() {
-  let { target, debuggee, panel } = await initShaderEditor(BLENDED_GEOMETRY_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, debuggee, panel } = yield initShaderEditor(BLENDED_GEOMETRY_CANVAS_URL);
   let { gFront, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  let [[firstProgramActor, secondProgramActor]] = await promise.all([
+  let [[firstProgramActor, secondProgramActor]] = yield promise.all([
     getPrograms(gFront, 2),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
   ok(true, "The canvas was correctly drawn.");
 
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 0) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 0, b: 32, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 0, b: 32, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 0, b: 32, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 0, b: 32, a: 127 }, true);
   ok(true, "The first program was correctly highlighted.");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 0) });
   ShadersListView._onProgramMouseOver({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 255, g: 0, b: 64, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 255, g: 0, b: 64, a: 255 }, true);
   ok(true, "The second program was correctly highlighted.");
 
   ShadersListView._onProgramMouseOut({ target: getItemLabel(panel, 1) });
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 127, g: 127, b: 127, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 127, b: 127, a: 127 }, true);
   ok(true, "The two programs were correctly unhighlighted.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
 
diff --git a/devtools/client/shadereditor/test/browser_se_programs-list.js b/devtools/client/shadereditor/test/browser_se_programs-list.js
index f7f9a0598860..6218808868e6 100644
--- a/devtools/client/shadereditor/test/browser_se_programs-list.js
+++ b/devtools/client/shadereditor/test/browser_se_programs-list.js
@@ -6,8 +6,8 @@
  * shaders are linked.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(MULTIPLE_CONTEXTS_URL);
   let { gFront, EVENTS, L10N, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   is(ShadersListView.itemCount, 0,
@@ -19,7 +19,7 @@ async function ifWebGLSupported() {
 
   reload(target);
 
-  let [firstProgramActor, secondProgramActor] = await promise.all([
+  let [firstProgramActor, secondProgramActor] = yield promise.all([
     getPrograms(gFront, 2, (actors) => {
       // Fired upon each actor addition, we want to check only
       // after the first actor has been added so we can test state
@@ -36,13 +36,13 @@ async function ifWebGLSupported() {
   is(ShadersListView.attachments[1].label, L10N.getFormatStr("shadersList.programLabel", 1),
     "The correct second label is shown in the shaders list.");
 
-  let vertexShader = await firstProgramActor.getVertexShader();
-  let fragmentShader = await firstProgramActor.getFragmentShader();
-  let vertSource = await vertexShader.getText();
-  let fragSource = await fragmentShader.getText();
+  let vertexShader = yield firstProgramActor.getVertexShader();
+  let fragmentShader = yield firstProgramActor.getFragmentShader();
+  let vertSource = yield vertexShader.getText();
+  let fragSource = yield fragmentShader.getText();
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   is(vertSource, vsEditor.getText(),
     "The vertex shader editor contains the correct text.");
@@ -58,14 +58,14 @@ async function ifWebGLSupported() {
   });
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, ShadersListView.items[1].target);
-  await shown;
+  yield shown;
 
   is(ShadersListView.selectedItem, ShadersListView.items[1],
     "The shaders list has a correct item selected.");
   is(ShadersListView.selectedIndex, 1,
     "The shaders list has a correct index selected.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 
   function checkFirstProgram() {
diff --git a/devtools/client/shadereditor/test/browser_se_shaders-edit-01.js b/devtools/client/shadereditor/test/browser_se_shaders-edit-01.js
index 1bedb529aa86..0cb52ac19644 100644
--- a/devtools/client/shadereditor/test/browser_se_shaders-edit-01.js
+++ b/devtools/client/shadereditor/test/browser_se_shaders-edit-01.js
@@ -5,18 +5,18 @@
  * Tests if editing a vertex and a fragment shader works properly.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, $, EVENTS, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   is(vsEditor.getText().indexOf("gl_Position"), 170,
     "The vertex shader editor contains the correct text.");
@@ -28,9 +28,9 @@ async function ifWebGLSupported() {
   is($("#fs-editor-label").hasAttribute("selected"), false,
     "The vertex shader editor shouldn't be initially selected.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 128, y: 128 }, { r: 191, g: 64, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 128, y: 128 }, { r: 191, g: 64, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
 
   vsEditor.focus();
 
@@ -40,13 +40,13 @@ async function ifWebGLSupported() {
     "The vertex shader editor shouldn't still not be selected.");
 
   vsEditor.replaceText("2.0", { line: 7, ch: 44 }, { line: 7, ch: 47 });
-  await once(panel.panelWin, EVENTS.SHADER_COMPILED);
+  yield once(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   ok(true, "Vertex shader was changed.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
 
   ok(true, "The vertex shader was recompiled successfully.");
 
@@ -58,16 +58,16 @@ async function ifWebGLSupported() {
     "The vertex shader editor should now be selected.");
 
   fsEditor.replaceText("0.5", { line: 5, ch: 44 }, { line: 5, ch: 47 });
-  await once(panel.panelWin, EVENTS.SHADER_COMPILED);
+  yield once(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   ok(true, "Fragment shader was changed.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 127 }, true);
-  await ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 127 }, true);
+  yield ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
 
   ok(true, "The fragment shader was recompiled successfully.");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_shaders-edit-02.js b/devtools/client/shadereditor/test/browser_se_shaders-edit-02.js
index bb590386f61a..354224e6b771 100644
--- a/devtools/client/shadereditor/test/browser_se_shaders-edit-02.js
+++ b/devtools/client/shadereditor/test/browser_se_shaders-edit-02.js
@@ -6,22 +6,22 @@
  * gets malformed after being edited.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(SIMPLE_CANVAS_URL);
   let { gFront, EVENTS, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(panel.panelWin, EVENTS.SOURCES_SHOWN)
   ]);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
 
   vsEditor.replaceText("vec3", { line: 7, ch: 22 }, { line: 7, ch: 26 });
-  let [, error] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  let [, error] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   ok(error,
     "The new vertex shader source was compiled with errors.");
@@ -42,7 +42,7 @@ async function ifWebGLSupported() {
 
 
   fsEditor.replaceText("vec4", { line: 2, ch: 14 }, { line: 2, ch: 18 });
-  [, error] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  [, error] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   ok(error,
     "The new fragment shader source was compiled with errors.");
@@ -57,20 +57,20 @@ async function ifWebGLSupported() {
     "A constructor error is contained in the info log.");
 
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
 
   vsEditor.replaceText("vec4", { line: 7, ch: 22 }, { line: 7, ch: 26 });
-  [, error] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  [, error] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   ok(!error, "The new vertex shader source was compiled successfully.");
 
   fsEditor.replaceText("vec3", { line: 2, ch: 14 }, { line: 2, ch: 18 });
-  [, error] = await onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
+  [, error] = yield onceSpread(panel.panelWin, EVENTS.SHADER_COMPILED);
   ok(!error, "The new fragment shader source was compiled successfully.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(gFront, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_se_shaders-edit-03.js b/devtools/client/shadereditor/test/browser_se_shaders-edit-03.js
index d5cec375c5e5..2c413dd72578 100644
--- a/devtools/client/shadereditor/test/browser_se_shaders-edit-03.js
+++ b/devtools/client/shadereditor/test/browser_se_shaders-edit-03.js
@@ -6,21 +6,21 @@
  * their new source on the backend and reshow it in the frontend when required.
  */
 
-async function ifWebGLSupported() {
-  let { target, panel } = await initShaderEditor(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, panel } = yield initShaderEditor(MULTIPLE_CONTEXTS_URL);
   let { gFront, EVENTS, ShadersListView, ShadersEditorsView } = panel.panelWin;
 
   reload(target);
 
-  await promise.all([
+  yield promise.all([
     once(gFront, "program-linked"),
     once(gFront, "program-linked")
   ]);
 
-  await once(panel.panelWin, EVENTS.SOURCES_SHOWN);
+  yield once(panel.panelWin, EVENTS.SOURCES_SHOWN);
 
-  let vsEditor = await ShadersEditorsView._getEditor("vs");
-  let fsEditor = await ShadersEditorsView._getEditor("fs");
+  let vsEditor = yield ShadersEditorsView._getEditor("vs");
+  let fsEditor = yield ShadersEditorsView._getEditor("fs");
 
   is(ShadersListView.selectedIndex, 0,
     "The first program is currently selected.");
@@ -34,26 +34,26 @@ async function ifWebGLSupported() {
     "The fragment shader editor contains the correct initial text (2).");
 
   vsEditor.replaceText("2.", { line: 5, ch: 44 }, { line: 5, ch: 45 });
-  await once(panel.panelWin, EVENTS.SHADER_COMPILED);
+  yield once(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   fsEditor.replaceText(".0", { line: 5, ch: 35 }, { line: 5, ch: 37 });
-  await once(panel.panelWin, EVENTS.SHADER_COMPILED);
+  yield once(panel.panelWin, EVENTS.SHADER_COMPILED);
 
   ok(true, "Vertex and fragment shaders were changed.");
 
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 32, y: 32 }, { r: 255, g: 255, b: 0, a: 0 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 255, g: 255, b: 0, a: 0 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 32, y: 32 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 32, y: 32 }, { r: 255, g: 255, b: 0, a: 0 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 255, g: 255, b: 0, a: 0 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(gFront, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 32, y: 32 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(gFront, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
 
   ok(true, "The vertex and fragment shaders were recompiled successfully.");
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, ShadersListView.items[1].target);
-  await once(panel.panelWin, EVENTS.SOURCES_SHOWN);
+  yield once(panel.panelWin, EVENTS.SOURCES_SHOWN);
 
   is(ShadersListView.selectedIndex, 1,
     "The second program is currently selected.");
@@ -67,7 +67,7 @@ async function ifWebGLSupported() {
     "The fragment shader editor contains the correct text (2).");
 
   EventUtils.sendMouseEvent({ type: "mousedown" }, ShadersListView.items[0].target);
-  await once(panel.panelWin, EVENTS.SOURCES_SHOWN);
+  yield once(panel.panelWin, EVENTS.SOURCES_SHOWN);
 
   is(ShadersListView.selectedIndex, 0,
     "The first program is currently selected again.");
@@ -80,6 +80,6 @@ async function ifWebGLSupported() {
   is(fsEditor.getText().indexOf(".0);"), 116,
     "The fragment shader editor contains the correct text (4).");
 
-  await teardown(panel);
+  yield teardown(panel);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-01.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-01.js
index 39737a14066e..242018a76823 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-01.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-01.js
@@ -5,12 +5,12 @@
  * Tests if a WebGL front can be created for a remote tab target.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
 
   ok(target, "Should have a target available.");
   ok(front, "Should have a protocol front available.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-02.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-02.js
index b39d440ed1fe..addec87ca000 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-02.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-02.js
@@ -6,8 +6,8 @@
  * if the front wasn't set up first.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
 
   once(front, "program-linked").then(() => {
     ok(false, "A 'program-linked' notification shouldn't have been sent!");
@@ -15,7 +15,7 @@ async function ifWebGLSupported() {
 
   ok(true, "Each test requires at least one pass, fail or todo so here is a pass.");
 
-  await reload(target);
-  await removeTab(target.tab);
+  yield reload(target);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-03.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-03.js
index efc2b4d53f45..0381973ec72d 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-03.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-03.js
@@ -6,21 +6,21 @@
  * after a target navigation.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
 
   let navigated = once(target, "navigate");
   let linked = once(front, "program-linked");
 
-  await front.setup({ reload: true });
+  yield front.setup({ reload: true });
   ok(true, "The front was setup up successfully.");
 
-  await navigated;
+  yield navigated;
   ok(true, "Target automatically navigated when the front was set up.");
 
-  await linked;
+  yield linked;
   ok(true, "A 'program-linked' notification was sent after reloading.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-04.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-04.js
index f5528b66531e..4256a5329784 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-04.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-04.js
@@ -6,22 +6,22 @@
  * and that the corresponding vertex and fragment actors can be retrieved.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
+  let programActor = yield once(front, "program-linked");
   ok(programActor,
     "A program actor was sent along with the 'program-linked' notification.");
 
-  let vertexShader = await programActor.getVertexShader();
+  let vertexShader = yield programActor.getVertexShader();
   ok(programActor,
     "A vertex shader actor was retrieved from the program actor.");
 
-  let fragmentShader = await programActor.getFragmentShader();
+  let fragmentShader = yield programActor.getFragmentShader();
   ok(programActor,
     "A fragment shader actor was retrieved from the program actor.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-05.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-05.js
index 01536344b239..96e445e01b29 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-05.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-05.js
@@ -6,22 +6,22 @@
  * shader actors.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
-  let vertexShader = await programActor.getVertexShader();
-  let fragmentShader = await programActor.getFragmentShader();
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
 
-  let vertSource = await vertexShader.getText();
+  let vertSource = yield vertexShader.getText();
   ok(vertSource.includes("gl_Position"),
     "The correct vertex shader source was retrieved.");
 
-  let fragSource = await fragmentShader.getText();
+  let fragSource = yield fragmentShader.getText();
   ok(fragSource.includes("gl_FragColor"),
     "The correct fragment shader source was retrieved.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-06.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-06.js
index 179309e35c0f..5cbe88a77ccc 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-06.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-06.js
@@ -6,59 +6,59 @@
  * program actors work as expected.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
-  let vertexShader = await programActor.getVertexShader();
-  let fragmentShader = await programActor.getFragmentShader();
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
-  await checkShaderSource("The shader sources are correct before highlighting.");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield checkShaderSource("The shader sources are correct before highlighting.");
   ok(true, "The corner pixel colors are correct before highlighting.");
 
-  await programActor.highlight([0, 1, 0, 1]);
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
-  await checkShaderSource("The shader sources are preserved after highlighting.");
+  yield programActor.highlight([0, 1, 0, 1]);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield checkShaderSource("The shader sources are preserved after highlighting.");
   ok(true, "The corner pixel colors are correct after highlighting.");
 
-  await programActor.unhighlight();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
-  await checkShaderSource("The shader sources are correct after unhighlighting.");
+  yield programActor.unhighlight();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield checkShaderSource("The shader sources are correct after unhighlighting.");
   ok(true, "The corner pixel colors are correct after unhighlighting.");
 
-  await programActor.blackbox();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await checkShaderSource("The shader sources are preserved after blackboxing.");
+  yield programActor.blackbox();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield checkShaderSource("The shader sources are preserved after blackboxing.");
   ok(true, "The corner pixel colors are correct after blackboxing.");
 
-  await programActor.unblackbox();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
-  await checkShaderSource("The shader sources are correct after unblackboxing.");
+  yield programActor.unblackbox();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield checkShaderSource("The shader sources are correct after unblackboxing.");
   ok(true, "The corner pixel colors are correct after unblackboxing.");
 
   function checkShaderSource(aMessage) {
-    return (async function () {
-      let newVertexShader = await programActor.getVertexShader();
-      let newFragmentShader = await programActor.getFragmentShader();
+    return Task.spawn(function* () {
+      let newVertexShader = yield programActor.getVertexShader();
+      let newFragmentShader = yield programActor.getFragmentShader();
       is(vertexShader, newVertexShader,
         "The same vertex shader actor was retrieved.");
       is(fragmentShader, newFragmentShader,
         "The same fragment shader actor was retrieved.");
 
-      let vertSource = await newVertexShader.getText();
-      let fragSource = await newFragmentShader.getText();
+      let vertSource = yield newVertexShader.getText();
+      let fragSource = yield newFragmentShader.getText();
       ok(vertSource.includes("I'm special!") &&
          fragSource.includes("I'm also special!"), aMessage);
-    })();
+    });
   }
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-07.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-07.js
index 75dc5f384385..a7634de44353 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-07.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-07.js
@@ -5,57 +5,57 @@
  * Tests that vertex and fragment shader sources can be changed.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
-  let vertexShader = await programActor.getVertexShader();
-  let fragmentShader = await programActor.getFragmentShader();
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 128, y: 128 }, { r: 191, g: 64, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 128, y: 128 }, { r: 191, g: 64, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
 
-  let vertSource = await vertexShader.getText();
-  let fragSource = await fragmentShader.getText();
+  let vertSource = yield vertexShader.getText();
+  let fragSource = yield fragmentShader.getText();
   ok(!vertSource.includes("2.0"),
     "The vertex shader source is correct before changing it.");
   ok(!fragSource.includes("0.5"),
     "The fragment shader source is correct before changing it.");
 
   let newVertSource = vertSource.replace("1.0", "2.0");
-  let status = await vertexShader.compile(newVertSource);
+  let status = yield vertexShader.compile(newVertSource);
   ok(!status,
     "The new vertex shader source was compiled without errors.");
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
 
-  vertSource = await vertexShader.getText();
-  fragSource = await fragmentShader.getText();
+  vertSource = yield vertexShader.getText();
+  fragSource = yield fragmentShader.getText();
   ok(vertSource.includes("2.0"),
     "The vertex shader source is correct after changing it.");
   ok(!fragSource.includes("0.5"),
     "The fragment shader source is correct after changing the vertex shader.");
 
   let newFragSource = fragSource.replace("1.0", "0.5");
-  status = await fragmentShader.compile(newFragSource);
+  status = yield fragmentShader.compile(newFragSource);
   ok(!status,
     "The new fragment shader source was compiled without errors.");
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 127 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 128, y: 128 }, { r: 255, g: 0, b: 0, a: 127 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 0, a: 255 }, true);
 
-  vertSource = await vertexShader.getText();
-  fragSource = await fragmentShader.getText();
+  vertSource = yield vertexShader.getText();
+  fragSource = yield fragmentShader.getText();
   ok(vertSource.includes("2.0"),
     "The vertex shader source is correct after changing the fragment shader.");
   ok(fragSource.includes("0.5"),
     "The fragment shader source is correct after changing it.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-08.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-08.js
index 044afc137941..8025bc7039a3 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-08.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-08.js
@@ -6,32 +6,32 @@
  * changed in one shader.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
-  let vertexShader = await programActor.getVertexShader();
-  let fragmentShader = await programActor.getFragmentShader();
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
 
-  let oldVertSource = await vertexShader.getText();
+  let oldVertSource = yield vertexShader.getText();
   let newVertSource = oldVertSource.replace("= aVertexColor", "= vec3(0, 0, 1)");
-  let status = await vertexShader.compile(newVertSource);
+  let status = yield vertexShader.compile(newVertSource);
   ok(!status,
     "The new vertex shader source was compiled without errors.");
 
-  await front.waitForFrame();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 255, a: 255 }, true);
-  await ensurePixelIs(front, { x: 128, y: 128 }, { r: 0, g: 0, b: 255, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 255, a: 255 }, true);
+  yield front.waitForFrame();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 255, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 128, y: 128 }, { r: 0, g: 0, b: 255, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 0, b: 255, a: 255 }, true);
 
-  let vertSource = await vertexShader.getText();
-  let fragSource = await fragmentShader.getText();
+  let vertSource = yield vertexShader.getText();
+  let fragSource = yield fragmentShader.getText();
   ok(vertSource.includes("vFragmentColor = vec3(0, 0, 1);"),
     "The vertex shader source is correct after changing it.");
   ok(fragSource.includes("gl_FragColor = vec4(vFragmentColor, 1.0);"),
     "The fragment shader source is correct after changing the vertex shader.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-09.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-09.js
index 27c4b69280ad..08e9543a77a2 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-09.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-09.js
@@ -6,19 +6,19 @@
  * defective shader source.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
-  let vertexShader = await programActor.getVertexShader();
-  let fragmentShader = await programActor.getFragmentShader();
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
 
-  let oldVertSource = await vertexShader.getText();
+  let oldVertSource = yield vertexShader.getText();
   let newVertSource = oldVertSource.replace("vec4", "vec3");
 
   try {
-    await vertexShader.compile(newVertSource);
+    yield vertexShader.compile(newVertSource);
     ok(false, "Vertex shader was compiled with a defective source!");
   } catch (error) {
     ok(error,
@@ -39,19 +39,19 @@ async function ifWebGLSupported() {
       "An assignment error is contained in the info log.");
   }
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
   ok(true, "The shader was reverted to the old source.");
 
-  let vertSource = await vertexShader.getText();
+  let vertSource = yield vertexShader.getText();
   ok(vertSource.includes("vec4(aVertexPosition, 1.0);"),
     "The previous correct vertex shader source was preserved.");
 
-  let oldFragSource = await fragmentShader.getText();
+  let oldFragSource = yield fragmentShader.getText();
   let newFragSource = oldFragSource.replace("vec3", "vec4");
 
   try {
-    await fragmentShader.compile(newFragSource);
+    yield fragmentShader.compile(newFragSource);
     ok(false, "Fragment shader was compiled with a defective source!");
   } catch (error) {
     ok(error,
@@ -68,24 +68,24 @@ async function ifWebGLSupported() {
       "A constructor error is contained in the info log.");
   }
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
   ok(true, "The shader was reverted to the old source.");
 
-  let fragSource = await fragmentShader.getText();
+  let fragSource = yield fragmentShader.getText();
   ok(fragSource.includes("vec3 vFragmentColor;"),
     "The previous correct fragment shader source was preserved.");
 
-  await programActor.highlight([0, 1, 0, 1]);
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield programActor.highlight([0, 1, 0, 1]);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
   ok(true, "Highlighting worked after setting a defective fragment source.");
 
-  await programActor.unhighlight();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+  yield programActor.unhighlight();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
   ok(true, "Unhighlighting worked after setting a defective vertex source.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-10.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-10.js
index 8310d4b21857..87dfe35bf6c4 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-10.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-10.js
@@ -6,39 +6,39 @@
  * target navigates.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
 
   front.setup({ reload: true });
-  await testHighlighting((await once(front, "program-linked")));
+  yield testHighlighting((yield once(front, "program-linked")));
   ok(true, "Canvas was correctly instrumented on the first navigation.");
 
   reload(target);
-  await testHighlighting((await once(front, "program-linked")));
+  yield testHighlighting((yield once(front, "program-linked")));
   ok(true, "Canvas was correctly instrumented on the second navigation.");
 
   reload(target);
-  await testHighlighting((await once(front, "program-linked")));
+  yield testHighlighting((yield once(front, "program-linked")));
   ok(true, "Canvas was correctly instrumented on the third navigation.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 
   function testHighlighting(programActor) {
-    return (async function () {
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+    return Task.spawn(function* () {
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct before highlighting.");
 
-      await programActor.highlight([0, 1, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+      yield programActor.highlight([0, 1, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct after highlighting.");
 
-      await programActor.unhighlight();
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+      yield programActor.unhighlight();
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct after unhighlighting.");
-    })();
+    });
   }
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-11.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-11.js
index 43f836fcd104..28663057ed08 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-11.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-11.js
@@ -6,20 +6,20 @@
  * finalize method is called.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
 
   let linked = once(front, "program-linked");
   front.setup({ reload: true });
-  await linked;
+  yield linked;
   ok(true, "Canvas was correctly instrumented on the first navigation.");
 
   once(front, "program-linked").then(() => {
     ok(false, "A 'program-linked' notification shouldn't have been sent!");
   });
 
-  await front.finalize();
-  await reload(target);
-  await removeTab(target.tab);
+  yield front.finalize();
+  yield reload(target);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-12.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-12.js
index e6c93483c3f9..f69d5e403fa5 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-12.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-12.js
@@ -6,22 +6,22 @@
  * regardless of the order in which they were compiled and attached.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SHADER_ORDER_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SHADER_ORDER_URL);
   front.setup({ reload: true });
 
-  let programActor = await once(front, "program-linked");
-  let vertexShader = await programActor.getVertexShader();
-  let fragmentShader = await programActor.getFragmentShader();
+  let programActor = yield once(front, "program-linked");
+  let vertexShader = yield programActor.getVertexShader();
+  let fragmentShader = yield programActor.getFragmentShader();
 
-  let vertSource = await vertexShader.getText();
-  let fragSource = await fragmentShader.getText();
+  let vertSource = yield vertexShader.getText();
+  let fragSource = yield fragmentShader.getText();
 
   ok(vertSource.includes("I'm a vertex shader!"),
     "The correct vertex shader text was retrieved.");
   ok(fragSource.includes("I'm a fragment shader!"),
     "The correct fragment shader text was retrieved.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-13.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-13.js
index 105068cc45ba..f4730ba39fd3 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-13.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-13.js
@@ -5,63 +5,63 @@
  * Tests if multiple WebGL contexts are correctly handled.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(MULTIPLE_CONTEXTS_URL);
   front.setup({ reload: true });
 
-  let [firstProgramActor, secondProgramActor] = await getPrograms(front, 2);
+  let [firstProgramActor, secondProgramActor] = yield getPrograms(front, 2);
 
   isnot(firstProgramActor, secondProgramActor,
     "Two distinct program actors were recevide from two separate contexts.");
 
-  let firstVertexShader = await firstProgramActor.getVertexShader();
-  let firstFragmentShader = await firstProgramActor.getFragmentShader();
-  let secondVertexShader = await secondProgramActor.getVertexShader();
-  let secondFragmentShader = await secondProgramActor.getFragmentShader();
+  let firstVertexShader = yield firstProgramActor.getVertexShader();
+  let firstFragmentShader = yield firstProgramActor.getFragmentShader();
+  let secondVertexShader = yield secondProgramActor.getVertexShader();
+  let secondFragmentShader = yield secondProgramActor.getFragmentShader();
 
   isnot(firstVertexShader, secondVertexShader,
     "The two programs should have distinct vertex shaders.");
   isnot(firstFragmentShader, secondFragmentShader,
     "The two programs should have distinct fragment shaders.");
 
-  let firstVertSource = await firstVertexShader.getText();
-  let firstFragSource = await firstFragmentShader.getText();
-  let secondVertSource = await secondVertexShader.getText();
-  let secondFragSource = await secondFragmentShader.getText();
+  let firstVertSource = yield firstVertexShader.getText();
+  let firstFragSource = yield firstFragmentShader.getText();
+  let secondVertSource = yield secondVertexShader.getText();
+  let secondFragSource = yield secondFragmentShader.getText();
 
   is(firstVertSource, secondVertSource,
     "The vertex shaders should have identical sources.");
   is(firstFragSource, secondFragSource,
     "The vertex shaders should have identical sources.");
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two canvases are correctly drawn.");
 
-  await firstProgramActor.highlight([1, 0, 0, 1]);
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield firstProgramActor.highlight([1, 0, 0, 1]);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The first canvas was correctly filled after highlighting.");
 
-  await secondProgramActor.highlight([0, 1, 0, 1]);
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+  yield secondProgramActor.highlight([0, 1, 0, 1]);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
   ok(true, "The second canvas was correctly filled after highlighting.");
 
-  await firstProgramActor.unhighlight();
-  await secondProgramActor.unhighlight();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield firstProgramActor.unhighlight();
+  yield secondProgramActor.unhighlight();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The two canvases were correctly filled after unhighlighting.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-14.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-14.js
index 7142c8e02bd0..342bba382b3d 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-14.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-14.js
@@ -6,41 +6,41 @@
  * changed in one shader of a page with multiple WebGL contexts.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(MULTIPLE_CONTEXTS_URL);
   front.setup({ reload: true });
 
-  let [firstProgramActor, secondProgramActor] = await getPrograms(front, 2);
+  let [firstProgramActor, secondProgramActor] = yield getPrograms(front, 2);
 
-  let firstFragmentShader = await firstProgramActor.getFragmentShader();
-  let secondFragmentShader = await secondProgramActor.getFragmentShader();
+  let firstFragmentShader = yield firstProgramActor.getFragmentShader();
+  let secondFragmentShader = yield secondProgramActor.getFragmentShader();
 
-  let oldFragSource = await firstFragmentShader.getText();
+  let oldFragSource = yield firstFragmentShader.getText();
   let newFragSource = oldFragSource.replace("vec4(uColor", "vec4(0.25, 0.25, 0.25");
-  let status = await firstFragmentShader.compile(newFragSource);
+  let status = yield firstFragmentShader.compile(newFragSource);
   ok(!status,
     "The first new fragment shader source was compiled without errors.");
 
-  await front.waitForFrame();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield front.waitForFrame();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
   ok(true, "The first fragment shader was changed.");
 
-  oldFragSource = await secondFragmentShader.getText();
+  oldFragSource = yield secondFragmentShader.getText();
   newFragSource = oldFragSource.replace("vec4(uColor", "vec4(0.75, 0.75, 0.75");
-  status = await secondFragmentShader.compile(newFragSource);
+  status = yield secondFragmentShader.compile(newFragSource);
   ok(!status,
     "The second new fragment shader source was compiled without errors.");
 
-  await front.waitForFrame();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 191, g: 191, b: 191, a: 255 }, true, "#canvas2");
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 191, g: 191, b: 191, a: 255 }, true, "#canvas2");
+  yield front.waitForFrame();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 64, g: 64, b: 64, a: 255 }, true, "#canvas1");
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 191, g: 191, b: 191, a: 255 }, true, "#canvas2");
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 191, g: 191, b: 191, a: 255 }, true, "#canvas2");
   ok(true, "The second fragment shader was changed.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-15.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-15.js
index 4d1ce2cb2af0..0a65dbe0ae72 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-15.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-15.js
@@ -5,8 +5,8 @@
  * Tests if program actors are cached when navigating in the bfcache.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: false });
 
   // Attach frame scripts if in e10s to perform
@@ -14,58 +14,58 @@ async function ifWebGLSupported() {
   loadFrameScripts();
 
   reload(target);
-  let firstProgram = await once(front, "program-linked");
-  await checkFirstCachedPrograms(firstProgram);
-  await checkHighlightingInTheFirstPage(firstProgram);
+  let firstProgram = yield once(front, "program-linked");
+  yield checkFirstCachedPrograms(firstProgram);
+  yield checkHighlightingInTheFirstPage(firstProgram);
   ok(true, "The cached programs behave correctly before the navigation.");
 
   navigate(target, MULTIPLE_CONTEXTS_URL);
-  let [secondProgram, thirdProgram] = await getPrograms(front, 2);
-  await checkSecondCachedPrograms(firstProgram, [secondProgram, thirdProgram]);
-  await checkHighlightingInTheSecondPage(secondProgram, thirdProgram);
+  let [secondProgram, thirdProgram] = yield getPrograms(front, 2);
+  yield checkSecondCachedPrograms(firstProgram, [secondProgram, thirdProgram]);
+  yield checkHighlightingInTheSecondPage(secondProgram, thirdProgram);
   ok(true, "The cached programs behave correctly after the navigation.");
 
   once(front, "program-linked").then(() => {
     ok(false, "Shouldn't have received any more program-linked notifications.");
   });
 
-  await navigateInHistory(target, "back");
-  await checkFirstCachedPrograms(firstProgram);
-  await checkHighlightingInTheFirstPage(firstProgram);
+  yield navigateInHistory(target, "back");
+  yield checkFirstCachedPrograms(firstProgram);
+  yield checkHighlightingInTheFirstPage(firstProgram);
   ok(true, "The cached programs behave correctly after navigating back.");
 
-  await navigateInHistory(target, "forward");
-  await checkSecondCachedPrograms(firstProgram, [secondProgram, thirdProgram]);
-  await checkHighlightingInTheSecondPage(secondProgram, thirdProgram);
+  yield navigateInHistory(target, "forward");
+  yield checkSecondCachedPrograms(firstProgram, [secondProgram, thirdProgram]);
+  yield checkHighlightingInTheSecondPage(secondProgram, thirdProgram);
   ok(true, "The cached programs behave correctly after navigating forward.");
 
-  await navigateInHistory(target, "back");
-  await checkFirstCachedPrograms(firstProgram);
-  await checkHighlightingInTheFirstPage(firstProgram);
+  yield navigateInHistory(target, "back");
+  yield checkFirstCachedPrograms(firstProgram);
+  yield checkHighlightingInTheFirstPage(firstProgram);
   ok(true, "The cached programs behave correctly after navigating back again.");
 
-  await navigateInHistory(target, "forward");
-  await checkSecondCachedPrograms(firstProgram, [secondProgram, thirdProgram]);
-  await checkHighlightingInTheSecondPage(secondProgram, thirdProgram);
+  yield navigateInHistory(target, "forward");
+  yield checkSecondCachedPrograms(firstProgram, [secondProgram, thirdProgram]);
+  yield checkHighlightingInTheSecondPage(secondProgram, thirdProgram);
   ok(true, "The cached programs behave correctly after navigating forward again.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 
   function checkFirstCachedPrograms(programActor) {
-    return (async function () {
-      let programs = await front.getPrograms();
+    return Task.spawn(function* () {
+      let programs = yield front.getPrograms();
 
       is(programs.length, 1,
         "There should be 1 cached program actor.");
       is(programs[0], programActor,
         "The cached program actor was the expected one.");
-    })();
+    });
   }
 
   function checkSecondCachedPrograms(oldProgramActor, newProgramActors) {
-    return (async function () {
-      let programs = await front.getPrograms();
+    return Task.spawn(function* () {
+      let programs = yield front.getPrograms();
 
       is(programs.length, 2,
         "There should be 2 cached program actors after the navigation.");
@@ -78,56 +78,56 @@ async function ifWebGLSupported() {
         "The old program actor is not equal to the new first program actor.");
       isnot(newProgramActors[1], oldProgramActor,
         "The old program actor is not equal to the new second program actor.");
-    })();
+    });
   }
 
   function checkHighlightingInTheFirstPage(programActor) {
-    return (async function () {
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+    return Task.spawn(function* () {
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct before highlighting.");
 
-      await programActor.highlight([0, 1, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+      yield programActor.highlight([0, 1, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct after highlighting.");
 
-      await programActor.unhighlight();
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+      yield programActor.unhighlight();
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct after unhighlighting.");
-    })();
+    });
   }
 
   function checkHighlightingInTheSecondPage(firstProgramActor, secondProgramActor) {
-    return (async function () {
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+    return Task.spawn(function* () {
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
       ok(true, "The two canvases are correctly drawn before highlighting.");
 
-      await firstProgramActor.highlight([1, 0, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield firstProgramActor.highlight([1, 0, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
       ok(true, "The first canvas was correctly filled after highlighting.");
 
-      await secondProgramActor.highlight([0, 1, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+      yield secondProgramActor.highlight([0, 1, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
       ok(true, "The second canvas was correctly filled after highlighting.");
 
-      await firstProgramActor.unhighlight();
-      await secondProgramActor.unhighlight();
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield firstProgramActor.unhighlight();
+      yield secondProgramActor.unhighlight();
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
       ok(true, "The two canvases were correctly filled after unhighlighting.");
-    })();
+    });
   }
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-16.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-16.js
index 81f16d0a7aa4..e61e73102924 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-16.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-16.js
@@ -6,8 +6,8 @@
  * removed from the bfcache.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(SIMPLE_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(SIMPLE_CANVAS_URL);
   front.setup({ reload: false });
 
   // Attach frame scripts if in e10s to perform
@@ -17,22 +17,22 @@ async function ifWebGLSupported() {
   // 0. Perform the initial reload.
 
   reload(target);
-  let firstProgram = await once(front, "program-linked");
-  let programs = await front.getPrograms();
+  let firstProgram = yield once(front, "program-linked");
+  let programs = yield front.getPrograms();
   is(programs.length, 1,
     "The first program should be returned by a call to getPrograms().");
   is(programs[0], firstProgram,
     "The first programs was correctly retrieved from the cache.");
 
-  let allPrograms = await front._getAllPrograms();
+  let allPrograms = yield front._getAllPrograms();
   is(allPrograms.length, 1,
     "Should be only one program in cache.");
 
   // 1. Perform a simple navigation.
 
   navigate(target, MULTIPLE_CONTEXTS_URL);
-  let [secondProgram, thirdProgram] = await getPrograms(front, 2);
-  programs = await front.getPrograms();
+  let [secondProgram, thirdProgram] = yield getPrograms(front, 2);
+  programs = yield front.getPrograms();
   is(programs.length, 2,
     "The second and third programs should be returned by a call to getPrograms().");
   is(programs[0], secondProgram,
@@ -40,33 +40,33 @@ async function ifWebGLSupported() {
   is(programs[1], thirdProgram,
     "The third programs was correctly retrieved from the cache.");
 
-  allPrograms = await front._getAllPrograms();
+  allPrograms = yield front._getAllPrograms();
   is(allPrograms.length, 3,
     "Should be three programs in cache.");
 
   // 2. Perform a bfcache navigation.
 
-  await navigateInHistory(target, "back");
+  yield navigateInHistory(target, "back");
   let globalDestroyed = once(front, "global-created");
   let globalCreated = once(front, "global-destroyed");
   let programsLinked = once(front, "program-linked");
   reload(target);
 
-  await promise.all([programsLinked, globalDestroyed, globalCreated]);
-  allPrograms = await front._getAllPrograms();
+  yield promise.all([programsLinked, globalDestroyed, globalCreated]);
+  allPrograms = yield front._getAllPrograms();
   is(allPrograms.length, 3,
     "Should be 3 programs total in cache.");
 
-  programs = await front.getPrograms();
+  programs = yield front.getPrograms();
   is(programs.length, 1,
     "There should be 1 cached program actor now.");
 
-  await checkHighlightingInTheFirstPage(programs[0]);
+  yield checkHighlightingInTheFirstPage(programs[0]);
   ok(true, "The cached programs behave correctly after navigating back and reloading.");
 
   // 3. Perform a bfcache navigation and a page reload.
 
-  await navigateInHistory(target, "forward");
+  yield navigateInHistory(target, "forward");
 
   globalDestroyed = once(front, "global-created");
   globalCreated = once(front, "global-destroyed");
@@ -74,68 +74,68 @@ async function ifWebGLSupported() {
 
   reload(target);
 
-  await promise.all([programsLinked, globalDestroyed, globalCreated]);
-  allPrograms = await front._getAllPrograms();
+  yield promise.all([programsLinked, globalDestroyed, globalCreated]);
+  allPrograms = yield front._getAllPrograms();
   is(allPrograms.length, 3,
     "Should be 3 programs total in cache.");
 
-  programs = await front.getPrograms();
+  programs = yield front.getPrograms();
   is(programs.length, 2,
     "There should be 2 cached program actors now.");
 
-  await checkHighlightingInTheSecondPage(programs[0], programs[1]);
+  yield checkHighlightingInTheSecondPage(programs[0], programs[1]);
   ok(true, "The cached programs behave correctly after navigating forward and reloading.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 
   function checkHighlightingInTheFirstPage(programActor) {
-    return (async function () {
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+    return Task.spawn(function* () {
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct before highlighting.");
 
-      await programActor.highlight([0, 1, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+      yield programActor.highlight([0, 1, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct after highlighting.");
 
-      await programActor.unhighlight();
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
-      await ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
+      yield programActor.unhighlight();
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true);
+      yield ensurePixelIs(front, { x: 511, y: 511 }, { r: 0, g: 255, b: 0, a: 255 }, true);
       ok(true, "The corner pixel colors are correct after unhighlighting.");
-    })();
+    });
   }
 
   function checkHighlightingInTheSecondPage(firstProgramActor, secondProgramActor) {
-    return (async function () {
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+    return Task.spawn(function* () {
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
       ok(true, "The two canvases are correctly drawn before highlighting.");
 
-      await firstProgramActor.highlight([1, 0, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield firstProgramActor.highlight([1, 0, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
       ok(true, "The first canvas was correctly filled after highlighting.");
 
-      await secondProgramActor.highlight([0, 1, 0, 1]);
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+      yield secondProgramActor.highlight([0, 1, 0, 1]);
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 0, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 0, a: 255 }, true, "#canvas2");
       ok(true, "The second canvas was correctly filled after highlighting.");
 
-      await firstProgramActor.unhighlight();
-      await secondProgramActor.unhighlight();
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
-      await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield firstProgramActor.unhighlight();
+      yield secondProgramActor.unhighlight();
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true, "#canvas1");
+      yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 255, b: 255, a: 255 }, true, "#canvas2");
       ok(true, "The two canvases were correctly filled after unhighlighting.");
-    })();
+    });
   }
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-17.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-17.js
index 6c60652b2ce6..92b940d4ab05 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-17.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-17.js
@@ -6,41 +6,41 @@
  * overlapping geometry.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(OVERLAPPING_GEOMETRY_CANVAS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(OVERLAPPING_GEOMETRY_CANVAS_URL);
   front.setup({ reload: true });
 
-  let [firstProgramActor, secondProgramActor] = await getPrograms(front, 2);
+  let [firstProgramActor, secondProgramActor] = yield getPrograms(front, 2);
 
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
   ok(true, "The corner vs. center pixel colors are correct before blackboxing.");
 
-  await firstProgramActor.blackbox();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield firstProgramActor.blackbox();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 0, g: 0, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 0, g: 0, b: 0, a: 255 }, true);
   ok(true, "The corner vs. center pixel colors are correct after blackboxing (1).");
 
-  await firstProgramActor.unblackbox();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield firstProgramActor.unblackbox();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
   ok(true, "The corner vs. center pixel colors are correct after unblackboxing (1).");
 
-  await secondProgramActor.blackbox();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 64, y: 64 }, { r: 255, g: 255, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield secondProgramActor.blackbox();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 64, y: 64 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
   ok(true, "The corner vs. center pixel colors are correct after blackboxing (2).");
 
-  await secondProgramActor.unblackbox();
-  await ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
-  await ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
-  await ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield secondProgramActor.unblackbox();
+  yield ensurePixelIs(front, { x: 0, y: 0 }, { r: 255, g: 255, b: 0, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 64, y: 64 }, { r: 0, g: 255, b: 255, a: 255 }, true);
+  yield ensurePixelIs(front, { x: 127, y: 127 }, { r: 255, g: 255, b: 0, a: 255 }, true);
   ok(true, "The corner vs. center pixel colors are correct after unblackboxing (2).");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/browser_webgl-actor-test-18.js b/devtools/client/shadereditor/test/browser_webgl-actor-test-18.js
index 6d863a6a9f03..977b07d86295 100644
--- a/devtools/client/shadereditor/test/browser_webgl-actor-test-18.js
+++ b/devtools/client/shadereditor/test/browser_webgl-actor-test-18.js
@@ -5,27 +5,27 @@
  * Tests the `getPixel` actor method works across threads.
  */
 
-async function ifWebGLSupported() {
-  let { target, front } = await initBackend(MULTIPLE_CONTEXTS_URL);
+function* ifWebGLSupported() {
+  let { target, front } = yield initBackend(MULTIPLE_CONTEXTS_URL);
   front.setup({ reload: true });
 
-  await getPrograms(front, 2);
+  yield getPrograms(front, 2);
 
   // Wait a frame to ensure rendering
-  await front.waitForFrame();
+  yield front.waitForFrame();
 
-  let pixel = await front.getPixel({ selector: "#canvas1", position: { x: 0, y: 0 }});
+  let pixel = yield front.getPixel({ selector: "#canvas1", position: { x: 0, y: 0 }});
   is(pixel.r, 255, "correct `r` value for first canvas.");
   is(pixel.g, 255, "correct `g` value for first canvas.");
   is(pixel.b, 0, "correct `b` value for first canvas.");
   is(pixel.a, 255, "correct `a` value for first canvas.");
 
-  pixel = await front.getPixel({ selector: "#canvas2", position: { x: 0, y: 0 }});
+  pixel = yield front.getPixel({ selector: "#canvas2", position: { x: 0, y: 0 }});
   is(pixel.r, 0, "correct `r` value for second canvas.");
   is(pixel.g, 255, "correct `g` value for second canvas.");
   is(pixel.b, 255, "correct `b` value for second canvas.");
   is(pixel.a, 255, "correct `a` value for second canvas.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
   finish();
 }
diff --git a/devtools/client/shadereditor/test/head.js b/devtools/client/shadereditor/test/head.js
index 87ad9793bbff..e150725ed0d2 100644
--- a/devtools/client/shadereditor/test/head.js
+++ b/devtools/client/shadereditor/test/head.js
@@ -68,13 +68,9 @@ function ifWebGLUnsupported() {
   finish();
 }
 
-async function test() {
+function test() {
   let generator = isWebGLSupported(document) ? ifWebGLSupported : ifWebGLUnsupported;
-  try {
-    await generator();
-  } catch(e) {
-    handlError(e);
-  }
+  Task.spawn(generator).catch(handleError);
 }
 
 function createCanvas() {
@@ -116,21 +112,21 @@ function isApproxColor(aFirst, aSecond, aMargin) {
 }
 
 function ensurePixelIs(aFront, aPosition, aColor, aWaitFlag = false, aSelector = "canvas") {
-  return (async function () {
-    let pixel = await aFront.getPixel({ selector: aSelector, position: aPosition });
+  return Task.spawn(function* () {
+    let pixel = yield aFront.getPixel({ selector: aSelector, position: aPosition });
     if (isApproxColor(pixel, aColor)) {
       ok(true, "Expected pixel is shown at: " + aPosition.toSource());
       return;
     }
 
     if (aWaitFlag) {
-      await aFront.waitForFrame();
+      yield aFront.waitForFrame();
       return ensurePixelIs(aFront, aPosition, aColor, aWaitFlag, aSelector);
     }
 
     ok(false, "Expected pixel was not already shown at: " + aPosition.toSource());
     throw new Error("Expected pixel was not already shown at: " + aPosition.toSource());
-  })();
+  });
 }
 
 function navigateInHistory(aTarget, aDirection, aWaitForTargetEvent = "navigate") {
@@ -159,31 +155,31 @@ function initBackend(aUrl) {
   DebuggerServer.init();
   DebuggerServer.registerAllActors();
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     let front = new WebGLFront(target.client, target.form);
     return { target, front };
-  })();
+  });
 }
 
 function initShaderEditor(aUrl) {
   info("Initializing a shader editor pane.");
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     Services.prefs.setBoolPref("devtools.shadereditor.enabled", true);
-    let toolbox = await gDevTools.showToolbox(target, "shadereditor");
+    let toolbox = yield gDevTools.showToolbox(target, "shadereditor");
     let panel = toolbox.getCurrentPanel();
     return { target, panel };
-  })();
+  });
 }
 
 function teardown(aPanel) {
diff --git a/devtools/client/shared/components/test/browser/browser_notification_box_basic.js b/devtools/client/shared/components/test/browser/browser_notification_box_basic.js
index 564602212b21..539977a51467 100644
--- a/devtools/client/shared/components/test/browser/browser_notification_box_basic.js
+++ b/devtools/client/shared/components/test/browser/browser_notification_box_basic.js
@@ -15,10 +15,10 @@ const TEST_URI = "data:text/html;charset=utf-8,Test page";
 /**
  * Basic test that checks existence of the Notification box.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test Notification box basic started");
 
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
 
   // Append a notification
   let notificationBox = toolbox.getNotificationBox();
diff --git a/devtools/client/shared/components/test/mochitest/head.js b/devtools/client/shared/components/test/mochitest/head.js
index 9ec43e103d6b..c756a65e615a 100644
--- a/devtools/client/shared/components/test/mochitest/head.js
+++ b/devtools/client/shared/components/test/mochitest/head.js
@@ -16,6 +16,7 @@ var { DebuggerServer } = require("devtools/server/main");
 var { DebuggerClient } = require("devtools/shared/client/debugger-client");
 var DevToolsUtils = require("devtools/shared/DevToolsUtils");
 var flags = require("devtools/shared/flags");
+var { Task } = require("devtools/shared/task");
 var { TargetFactory } = require("devtools/client/framework/target");
 var { Toolbox } = require("devtools/client/framework/toolbox");
 
diff --git a/devtools/client/shared/components/test/mochitest/test_HSplitBox_01.html b/devtools/client/shared/components/test/mochitest/test_HSplitBox_01.html
index 0dfeba59a1da..d65bbe70bebb 100644
--- a/devtools/client/shared/components/test/mochitest/test_HSplitBox_01.html
+++ b/devtools/client/shared/components/test/mochitest/test_HSplitBox_01.html
@@ -30,7 +30,7 @@ function aboutEq(a, b) {
   return Math.abs(a - b) < FUDGE_FACTOR;
 }
 
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const React = browserRequire("devtools/client/shared/vendor/react");
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
@@ -125,7 +125,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_frame_01.html b/devtools/client/shared/components/test/mochitest/test_frame_01.html
index 4ba789fb25c4..2128f2fb31ac 100644
--- a/devtools/client/shared/components/test/mochitest/test_frame_01.html
+++ b/devtools/client/shared/components/test/mochitest/test_frame_01.html
@@ -17,7 +17,7 @@ with optional columns, unknown and non-URL sources.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -25,7 +25,7 @@ window.onload = async function () {
     ok(Frame, "Should get Frame");
 
     // Check when there's a column
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 55,
@@ -40,7 +40,7 @@ window.onload = async function () {
     });
 
     // Check when there's no column
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 55,
@@ -53,7 +53,7 @@ window.onload = async function () {
     });
 
     // Check when column === 0
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 55,
@@ -68,7 +68,7 @@ window.onload = async function () {
 
     // Check when there's no parseable URL source;
     // should not link but should render line/columns
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "self-hosted",
         line: 1,
@@ -79,7 +79,7 @@ window.onload = async function () {
       shouldLink: false,
       tooltip: "self-hosted:1",
     });
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "self-hosted",
         line: 1,
@@ -95,7 +95,7 @@ window.onload = async function () {
 
     // Check when there's no source;
     // should not link but should render line/columns
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         line: 1,
       }
@@ -105,7 +105,7 @@ window.onload = async function () {
       shouldLink: false,
       tooltip: "(unknown):1",
     });
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         line: 1,
         column: 10,
@@ -120,7 +120,7 @@ window.onload = async function () {
 
     // Check when there's a column, but no line;
     // no line/column info should render
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         column: 55,
@@ -133,7 +133,7 @@ window.onload = async function () {
 
     // Check when line is 0; this should be an invalid
     // line option, so don't render line/column
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 0,
@@ -147,7 +147,7 @@ window.onload = async function () {
 
     // Check when source is via Scratchpad; we should render out the
     // lines and columns as this is linkable.
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "Scratchpad/1",
         line: 10,
@@ -162,7 +162,7 @@ window.onload = async function () {
     });
 
     // Check that line and column can be strings
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: "10",
@@ -178,7 +178,7 @@ window.onload = async function () {
 
     // Check that line and column can be strings,
     // and that the `0` rendering rules apply when they are strings as well
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: "0",
@@ -191,7 +191,7 @@ window.onload = async function () {
     });
 
     // Check that the showFullSourceUrl option works correctly
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 0,
@@ -204,7 +204,7 @@ window.onload = async function () {
     });
 
     // Check that the showFunctionName option works correctly
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         functionDisplayName: "myfun",
         source: "http://myfile.com/mahscripts.js",
@@ -217,7 +217,7 @@ window.onload = async function () {
       tooltip: "View source in Debugger → http://myfile.com/mahscripts.js",
     });
 
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         functionDisplayName: "myfun",
         source: "http://myfile.com/mahscripts.js",
@@ -232,7 +232,7 @@ window.onload = async function () {
     });
 
     // Check that anonymous function name is not displayed unless explicitly enabled
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 0,
@@ -245,7 +245,7 @@ window.onload = async function () {
       tooltip: "View source in Debugger → http://myfile.com/mahscripts.js",
     });
 
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://myfile.com/mahscripts.js",
         line: 0,
@@ -260,7 +260,7 @@ window.onload = async function () {
     });
 
     // Check if file is rendered with "/" for root documents when showEmptyPathAsHost is false
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://www.cnn.com/",
         line: "1",
@@ -274,7 +274,7 @@ window.onload = async function () {
     });
 
     // Check if file is rendered with hostname for root documents when showEmptyPathAsHost is true
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
         source: "http://www.cnn.com/",
         line: "1",
@@ -300,7 +300,7 @@ window.onload = async function () {
       unsubscribe: function (url, line, column, callback) {
       },
     };
-    await checkFrameComponent({
+    yield checkFrameComponent({
       frame: {
 	line: 97,
 	source: "https://bugzilla.mozilla.org/bundle.js",
@@ -314,7 +314,7 @@ window.onload = async function () {
       source: "https://bugzilla.mozilla.org/original.js",
     });
 
-    function checkFrameComponent(input, expected) {
+    function* checkFrameComponent(input, expected) {
       let props = Object.assign({ onClick: () => {} }, input);
       let frame = ReactDOM.render(Frame(props), window.document.body);
       let el = ReactDOM.findDOMNode(frame);
@@ -328,7 +328,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_frame_02.html b/devtools/client/shared/components/test/mochitest/test_frame_02.html
index e23169ad5d0d..e419e599254b 100644
--- a/devtools/client/shared/components/test/mochitest/test_frame_02.html
+++ b/devtools/client/shared/components/test/mochitest/test_frame_02.html
@@ -16,7 +16,7 @@ Test that the frame component reacts to source-map pref changse.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const Services = browserRequire("Services");
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
@@ -90,7 +90,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_notification_box_01.html b/devtools/client/shared/components/test/mochitest/test_notification_box_01.html
index 3efd648d4c73..dfb7a2c853a3 100644
--- a/devtools/client/shared/components/test/mochitest/test_notification_box_01.html
+++ b/devtools/client/shared/components/test/mochitest/test_notification_box_01.html
@@ -20,7 +20,7 @@ Test for Notification Box. The test is checking:
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -95,7 +95,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 
 function checkNumberOfNotifications(notificationBox, expected) {
   is(TestUtils.scryRenderedDOMComponentsWithClass(
diff --git a/devtools/client/shared/components/test/mochitest/test_notification_box_02.html b/devtools/client/shared/components/test/mochitest/test_notification_box_02.html
index cf93996aac7b..3992c1ab02cf 100644
--- a/devtools/client/shared/components/test/mochitest/test_notification_box_02.html
+++ b/devtools/client/shared/components/test/mochitest/test_notification_box_02.html
@@ -17,7 +17,7 @@ Test for Notification Box. The test is checking:
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -63,7 +63,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_notification_box_03.html b/devtools/client/shared/components/test/mochitest/test_notification_box_03.html
index 3594f7b7ef06..70408a1debc0 100644
--- a/devtools/client/shared/components/test/mochitest/test_notification_box_03.html
+++ b/devtools/client/shared/components/test/mochitest/test_notification_box_03.html
@@ -17,7 +17,7 @@ Test for Notification Box. The test is checking:
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -77,7 +77,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_sidebar_toggle.html b/devtools/client/shared/components/test/mochitest/test_sidebar_toggle.html
index 31445beb206d..bb68a8a8b37c 100644
--- a/devtools/client/shared/components/test/mochitest/test_sidebar_toggle.html
+++ b/devtools/client/shared/components/test/mochitest/test_sidebar_toggle.html
@@ -16,11 +16,11 @@ Test sidebar toggle button
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   let SidebarToggle = browserRequire("devtools/client/shared/components/SidebarToggle.js");
 
   try {
-    await test();
+    yield test();
   } catch(e) {
     ok(false, "Got an error: " + DevToolsUtils.safeErrorString(e));
   } finally {
@@ -49,7 +49,7 @@ window.onload = async function () {
     ok(output2.props.className.includes("pane-collapsed"),
       "Proper class name is set");
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_stack-trace-source-maps.html b/devtools/client/shared/components/test/mochitest/test_stack-trace-source-maps.html
index 20124c104bb4..4a53266a4474 100644
--- a/devtools/client/shared/components/test/mochitest/test_stack-trace-source-maps.html
+++ b/devtools/client/shared/components/test/mochitest/test_stack-trace-source-maps.html
@@ -27,7 +27,7 @@ window.onload = function () {
   );
   ok(StackTrace, "Got the StackTrace factory");
 
-  add_task(async function () {
+  add_task(function* () {
     let stacktrace = [
       {
         filename: "https://bugzilla.mozilla.org/bundle.js",
@@ -59,7 +59,7 @@ window.onload = function () {
     };
 
     let trace = ReactDOM.render(StackTrace(props), window.document.body);
-    await forceRender(trace);
+    yield forceRender(trace);
 
     let traceEl = ReactDOM.findDOMNode(trace);
     ok(traceEl, "Rendered StackTrace has an element");
diff --git a/devtools/client/shared/components/test/mochitest/test_stack-trace.html b/devtools/client/shared/components/test/mochitest/test_stack-trace.html
index 39489ee729f8..38e7790a7f63 100644
--- a/devtools/client/shared/components/test/mochitest/test_stack-trace.html
+++ b/devtools/client/shared/components/test/mochitest/test_stack-trace.html
@@ -27,7 +27,7 @@ window.onload = function () {
   );
   ok(StackTrace, "Got the StackTrace factory");
 
-  add_task(async function () {
+  add_task(function* () {
     let stacktrace = [
       {
         filename: "http://myfile.com/mahscripts.js",
@@ -49,7 +49,7 @@ window.onload = function () {
     };
 
     let trace = ReactDOM.render(StackTrace(props), window.document.body);
-    await forceRender(trace);
+    yield forceRender(trace);
 
     let traceEl = ReactDOM.findDOMNode(trace);
     ok(traceEl, "Rendered StackTrace has an element");
diff --git a/devtools/client/shared/components/test/mochitest/test_tabs_accessibility.html b/devtools/client/shared/components/test/mochitest/test_tabs_accessibility.html
index 6cfd5e3565dc..637d462257ac 100644
--- a/devtools/client/shared/components/test/mochitest/test_tabs_accessibility.html
+++ b/devtools/client/shared/components/test/mochitest/test_tabs_accessibility.html
@@ -16,7 +16,7 @@ Test tabs accessibility.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -32,8 +32,8 @@ window.onload = async function () {
     tabpanels.id = "tabpanels";
     document.body.appendChild(tabpanels);
 
-    await addTabWithPanel(0);
-    await addTabWithPanel(1);
+    yield addTabWithPanel(0);
+    yield addTabWithPanel(1);
 
     const tabAnchors = tabbarEl.querySelectorAll("li.tabs-menu-item a");
 
@@ -46,7 +46,7 @@ window.onload = async function () {
     is(tabAnchors[1].getAttribute("aria-selected"), "false", "Anchor aria-selected is set correctly by default");
     is(tabAnchors[1].getAttribute("aria-controls"), "sidebar-1-panel", "Anchor aria-controls is set correctly");
 
-    await setState(tabbarReact, Object.assign({}, tabbarReact.state, {
+    yield setState(tabbarReact, Object.assign({}, tabbarReact.state, {
       activeTab: 1
     }));
 
@@ -72,7 +72,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tabs_menu.html b/devtools/client/shared/components/test/mochitest/test_tabs_menu.html
index a2b6705ab0ad..c92c896aa153 100644
--- a/devtools/client/shared/components/test/mochitest/test_tabs_menu.html
+++ b/devtools/client/shared/components/test/mochitest/test_tabs_menu.html
@@ -22,7 +22,7 @@ Test all-tabs menu.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { Component, createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -55,11 +55,11 @@ window.onload = async function () {
     let TabPanel = createFactory(TabPanelClass);
 
     // Create a few panels.
-    await addTabWithPanel(1);
-    await addTabWithPanel(2);
-    await addTabWithPanel(3);
-    await addTabWithPanel(4);
-    await addTabWithPanel(5);
+    yield addTabWithPanel(1);
+    yield addTabWithPanel(2);
+    yield addTabWithPanel(3);
+    yield addTabWithPanel(4);
+    yield addTabWithPanel(5);
 
     // Make sure the all-tabs menu is there.
     const allTabsMenu = tabBarBox.querySelector(".all-tabs-menu");
@@ -76,7 +76,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_01.html b/devtools/client/shared/components/test/mochitest/test_tree_01.html
index f643c492d540..6573e46efae2 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_01.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_01.html
@@ -17,7 +17,7 @@ depth.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -34,7 +34,7 @@ window.onload = async function () {
     isAccessibleTree(tree);
 
     TEST_TREE.expanded = new Set("ABCDEFGHIJKLMNO".split(""));
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -58,7 +58,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_02.html b/devtools/client/shared/components/test/mochitest/test_tree_02.html
index 0b318d48ef84..db6f4896526b 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_02.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_02.html
@@ -16,7 +16,7 @@ Test that collapsed subtrees aren't rendered.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -26,7 +26,7 @@ window.onload = async function () {
 
     isAccessibleTree(tree);
     TEST_TREE.expanded = new Set("MNO".split(""));
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -39,7 +39,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_03.html b/devtools/client/shared/components/test/mochitest/test_tree_03.html
index d4d3342396ed..2b384ba0b99e 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_03.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_03.html
@@ -16,7 +16,7 @@ Test Tree's autoExpandDepth.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     let ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     let React = browserRequire("devtools/client/shared/vendor/react");
@@ -40,7 +40,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_04.html b/devtools/client/shared/components/test/mochitest/test_tree_04.html
index e647377a5584..04f2846260a9 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_04.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_04.html
@@ -16,7 +16,7 @@ Test that we only render visible tree items.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     function getSpacerHeights() {
       return {
@@ -37,7 +37,7 @@ window.onload = async function () {
 
     TEST_TREE.expanded = new Set("ABCDEFGHIJKLMNO".split(""));
 
-    await setState(tree, {
+    yield setState(tree, {
       height: 3 * ITEM_HEIGHT,
       scroll: 1 * ITEM_HEIGHT
     });
@@ -55,7 +55,7 @@ window.onload = async function () {
     is(spacers.top, 0, "Top spacer has the correct height");
     is(spacers.bottom, 10 * ITEM_HEIGHT, "Bottom spacer has the correct height");
 
-    await setState(tree, {
+    yield setState(tree, {
       height: 2 * ITEM_HEIGHT,
       scroll: 3 * ITEM_HEIGHT
     });
@@ -74,7 +74,7 @@ window.onload = async function () {
 
     // Set height to 2 items + 1 pixel at each end, scroll so that 4 items are visible
     // (2 fully, 2 partially with 1 visible pixel)
-    await setState(tree, {
+    yield setState(tree, {
       height: 2 * ITEM_HEIGHT + 2,
       scroll: 3 * ITEM_HEIGHT - 1
     });
@@ -92,7 +92,7 @@ window.onload = async function () {
     is(spacers.top, 1 * ITEM_HEIGHT, "Top spacer has the correct height");
     is(spacers.bottom, 8 * ITEM_HEIGHT, "Bottom spacer has the correct height");
 
-    await setState(tree, {
+    yield setState(tree, {
       height: 20 * ITEM_HEIGHT,
       scroll: 0
     });
@@ -123,7 +123,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_06.html b/devtools/client/shared/components/test/mochitest/test_tree_06.html
index ad1b342f31e8..606d371324b3 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_06.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_06.html
@@ -16,7 +16,7 @@ Test keyboard navigation with the Tree component.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -42,7 +42,7 @@ window.onload = async function () {
     info("Up to the previous sibling.");
     renderTree({ focused: "L" });
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowUp" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -64,7 +64,7 @@ window.onload = async function () {
 
     info("Up to the parent.");
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowUp" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -87,7 +87,7 @@ window.onload = async function () {
     info("Try and navigate up, past the first item.");
     renderTree({ focused: "A" });
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowUp" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:true",
@@ -112,7 +112,7 @@ window.onload = async function () {
     info("Down to next sibling.");
     renderTree({ focused: "K" });
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowDown" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -134,7 +134,7 @@ window.onload = async function () {
 
     info("Down to parent's next sibling.");
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowDown" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -157,7 +157,7 @@ window.onload = async function () {
     info("Try and go down past the last item.");
     renderTree({ focused: "O" });
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowDown" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -182,7 +182,7 @@ window.onload = async function () {
     info("Left to go to parent.");
     renderTree({ focused: "L" });
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowLeft" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -204,7 +204,7 @@ window.onload = async function () {
 
     info("Left to collapse children.");
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowLeft" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -226,7 +226,7 @@ window.onload = async function () {
 
     info("Right to expand children.");
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowRight" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -248,7 +248,7 @@ window.onload = async function () {
 
     info("Right to go to next item.");
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowRight" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "A:false",
@@ -277,7 +277,7 @@ window.onload = async function () {
     ];
     for (let key of keysWithModifier) {
       Simulate.keyDown(document.querySelector(".tree"), key);
-      await forceRender(tree);
+      yield forceRender(tree);
 
       isRenderedTree(document.body.textContent, [
         "A:false",
@@ -302,7 +302,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_07.html b/devtools/client/shared/components/test/mochitest/test_tree_07.html
index 0fd1011ba5d7..6d0a11bd1891 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_07.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_07.html
@@ -17,7 +17,7 @@ Test that arrows get the open attribute when their item's children are expanded.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const React = browserRequire("devtools/client/shared/vendor/react");
@@ -40,7 +40,7 @@ window.onload = async function () {
     const tree = ReactDOM.render(Tree(treeProps), window.document.body);
 
     TEST_TREE.expanded = new Set("ABCDEFGHIJKLMNO".split(""));
-    await forceRender(tree);
+    yield forceRender(tree);
 
     let arrows = document.querySelectorAll(".arrow");
     for (let a of arrows) {
@@ -48,7 +48,7 @@ window.onload = async function () {
     }
 
     TEST_TREE.expanded = new Set();
-    await forceRender(tree);
+    yield forceRender(tree);
 
     arrows = document.querySelectorAll(".arrow");
     for (let a of arrows) {
@@ -59,7 +59,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_08.html b/devtools/client/shared/components/test/mochitest/test_tree_08.html
index 2eb00d33f5f2..ad07afc836a5 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_08.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_08.html
@@ -18,7 +18,7 @@ other inputs.
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -42,7 +42,7 @@ window.onload = async function () {
     is(document.activeElement, input, "The text input should be focused.");
 
     document.querySelector(".tree-node").click();
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isnot(document.activeElement, input,
           "The input should have had it's focus stolen by clicking on a tree item.");
@@ -51,7 +51,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_09.html b/devtools/client/shared/components/test/mochitest/test_tree_09.html
index bc5fecce653e..ea37445c01f8 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_09.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_09.html
@@ -17,7 +17,7 @@ Test that when an item in the Tree component is expanded or collapsed the approp
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -59,14 +59,14 @@ window.onload = async function () {
 
     // Expand "A" via the keyboard and then let the component re-render.
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowRight" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     is(lastExpandedItem, "A", "Our onExpand callback should have been fired.");
     is(numberOfExpands, 1);
 
     // Now collapse "A" via the keyboard and then let the component re-render.
     Simulate.keyDown(document.querySelector(".tree"), { key: "ArrowLeft" });
-    await forceRender(tree);
+    yield forceRender(tree);
 
     is(lastCollapsedItem, "A", "Our onCollapsed callback should have been fired.");
     is(numberOfCollapses, 1);
@@ -75,7 +75,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_10.html b/devtools/client/shared/components/test/mochitest/test_tree_10.html
index 975535e22028..749b2dc4486d 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_10.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_10.html
@@ -17,7 +17,7 @@ Test that when an item in the Tree component is expanded or collapsed the approp
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -47,7 +47,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/components/test/mochitest/test_tree_11.html b/devtools/client/shared/components/test/mochitest/test_tree_11.html
index af2623bfde3f..68bb19d6d253 100644
--- a/devtools/client/shared/components/test/mochitest/test_tree_11.html
+++ b/devtools/client/shared/components/test/mochitest/test_tree_11.html
@@ -28,7 +28,7 @@ Test that when an item in the Tree component is focused by arrow key, the view i
 <pre id="test">
 <script src="head.js" type="application/javascript"></script>
 <script type="application/javascript">
-window.onload = async function () {
+window.onload = Task.async(function* () {
   try {
     const ReactDOM = browserRequire("devtools/client/shared/vendor/react-dom");
     const { createFactory } = browserRequire("devtools/client/shared/vendor/react");
@@ -61,7 +61,7 @@ window.onload = async function () {
       "---L:false",
     ], "Should render initial correctly");
 
-    await new Promise(resolve => {
+    yield new Promise(resolve => {
       const treeElem = document.querySelector(".tree");
       treeElem.addEventListener("scroll", function onScroll() {
         dumpn("Got scroll event");
@@ -74,7 +74,7 @@ window.onload = async function () {
     });
 
     dumpn("Forcing re-render");
-    await forceRender(tree);
+    yield forceRender(tree);
 
     isRenderedTree(document.body.textContent, [
       "-B:false",
@@ -89,7 +89,7 @@ window.onload = async function () {
   } finally {
     SimpleTest.finish();
   }
-};
+});
 </script>
 </pre>
 </body>
diff --git a/devtools/client/shared/developer-toolbar.js b/devtools/client/shared/developer-toolbar.js
index 57ce94fdd265..68f7c2bf9f31 100644
--- a/devtools/client/shared/developer-toolbar.js
+++ b/devtools/client/shared/developer-toolbar.js
@@ -11,6 +11,7 @@ const { TargetFactory } = require("devtools/client/framework/target");
 const Telemetry = require("devtools/client/shared/telemetry");
 const {LocalizationHelper} = require("devtools/shared/l10n");
 const L10N = new LocalizationHelper("devtools/client/locales/toolbox.properties");
+const {Task} = require("devtools/shared/task");
 
 const NS_XHTML = "http://www.w3.org/1999/xhtml";
 
@@ -42,7 +43,7 @@ var CommandUtils = {
   /**
    * Utility to execute a command string on a given target
    */
-  async executeOnTarget(target, command) {
+  executeOnTarget: Task.async(function* (target, command) {
     let requisitionPromise = this._requisitions.get(target);
     if (!requisitionPromise) {
       requisitionPromise = this.createRequisition(target, {
@@ -51,9 +52,9 @@ var CommandUtils = {
       // Store the promise to avoid races by storing the promise immediately
       this._requisitions.set(target, requisitionPromise);
     }
-    let requisition = await requisitionPromise;
+    let requisition = yield requisitionPromise;
     requisition.updateExec(command);
-  },
+  }),
 
   /**
    * Utility to ensure that things are loaded in the correct order
@@ -370,15 +371,15 @@ DeveloperToolbar.prototype.show = function (focus) {
     return this._showPromise;
   }
 
-  this._showPromise = ((async function () {
+  this._showPromise = Task.spawn((function* () {
     // hide() is async, so ensure we don't need to wait for hide() to
     // finish.  We unconditionally yield here, even if _hidePromise is
     // null, so that the spawn call returns a promise before starting
     // to do any real work.
-    await this._hidePromise;
+    yield this._hidePromise;
 
     // Append the browser-level stylesheet to the browser document.
-    await gDevToolsBrowser.loadBrowserStyleSheet(this._chromeWindow);
+    yield gDevToolsBrowser.loadBrowserStyleSheet(this._chromeWindow);
 
     this.createToolbar();
 
@@ -396,7 +397,7 @@ DeveloperToolbar.prototype.show = function (focus) {
       TooltipPanel.create(this),
       OutputPanel.create(this)
     ];
-    let panels = await promise.all(panelPromises);
+    let panels = yield promise.all(panelPromises);
 
     [ this.tooltipPanel, this.outputPanel ] = panels;
 
@@ -407,13 +408,13 @@ DeveloperToolbar.prototype.show = function (focus) {
       environment: CommandUtils.createEnvironment(this, "target"),
       document: this.outputPanel.document,
     };
-    let requisition = await CommandUtils.createRequisition(this.target, options);
+    let requisition = yield CommandUtils.createRequisition(this.target, options);
     this.requisition = requisition;
 
     // The <textbox> `value` may still be undefined on the XUL binding if
     // we fetch it early
     let value = this._input.value || "";
-    await this.requisition.update(value);
+    yield this.requisition.update(value);
 
     const Inputter = require("gcli/mozui/inputter").Inputter;
     const Completer = require("gcli/mozui/completer").Completer;
@@ -469,7 +470,7 @@ DeveloperToolbar.prototype.show = function (focus) {
     this._element.hidden = false;
 
     if (focus) {
-      await this.focus();
+      yield this.focus();
     }
     this._notify(NOTIFICATIONS.SHOW);
 
@@ -480,7 +481,7 @@ DeveloperToolbar.prototype.show = function (focus) {
                            this.outputPanel);
       DeveloperToolbar.introShownThisSession = true;
     }
-  }).bind(this))();
+  }).bind(this));
 
   return this._showPromise;
 };
diff --git a/devtools/client/shared/doorhanger.js b/devtools/client/shared/doorhanger.js
index 57eca8564538..fb73d92aeb1c 100644
--- a/devtools/client/shared/doorhanger.js
+++ b/devtools/client/shared/doorhanger.js
@@ -6,6 +6,7 @@
 
 const Services = require("Services");
 const { DOMHelpers } = require("resource://devtools/client/shared/DOMHelpers.jsm");
+const { Task } = require("devtools/shared/task");
 
 const XULNS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 const DEV_EDITION_PROMO_URL = "chrome://devtools/content/framework/dev-edition-promo/dev-edition-promo.xul";
@@ -64,7 +65,7 @@ var panelAttrs = {
  *        The selector that the doorhanger should be appended to within
  *        `window`.  Defaults to a XUL Document's `window` element.
  */
-exports.showDoorhanger = async function ({ window, type, anchor }) {
+exports.showDoorhanger = Task.async(function* ({ window, type, anchor }) {
   let { predicate, success, url, action } = TYPES[type];
   // Abort if predicate fails
   if (!predicate()) {
@@ -77,7 +78,7 @@ exports.showDoorhanger = async function ({ window, type, anchor }) {
 
   // Wait 200ms to prevent flickering where the popup is displayed
   // before the underlying window (Windows 7, 64bit)
-  await wait(200);
+  yield wait(200);
 
   let document = window.document;
 
@@ -93,7 +94,7 @@ exports.showDoorhanger = async function ({ window, type, anchor }) {
   panel.appendChild(frame);
   parentEl.appendChild(panel);
 
-  await onFrameLoad(frame);
+  yield onFrameLoad(frame);
 
   panel.openPopup(anchor);
 
@@ -111,7 +112,7 @@ exports.showDoorhanger = async function ({ window, type, anchor }) {
       close();
     });
   }
-};
+});
 
 function setDoorhangerStyle(panel, frame) {
   Object.keys(panelAttrs).forEach(prop => {
diff --git a/devtools/client/shared/redux/middleware/test/test_middleware-task-01.js b/devtools/client/shared/redux/middleware/test/test_middleware-task-01.js
index ce5f05b707f6..a52fa55009ae 100644
--- a/devtools/client/shared/redux/middleware/test/test_middleware-task-01.js
+++ b/devtools/client/shared/redux/middleware/test/test_middleware-task-01.js
@@ -16,26 +16,26 @@ function run_test() {
   run_next_test();
 }
 
-add_task(async function () {
+add_task(function* () {
   let store = applyMiddleware(task)(createStore)(reducer);
 
   store.dispatch(fetch1("generator"));
-  await waitUntilState(store, () => store.getState().length === 1);
+  yield waitUntilState(store, () => store.getState().length === 1);
   equal(store.getState()[0].data, "generator",
         "task middleware async dispatches an action via generator");
 
   store.dispatch(fetch2("sync"));
-  await waitUntilState(store, () => store.getState().length === 2);
+  yield waitUntilState(store, () => store.getState().length === 2);
   equal(store.getState()[1].data, "sync",
         "task middleware sync dispatches an action via sync");
 });
 
 function fetch1(data) {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     equal(getState().length, 0, "`getState` is accessible in a generator action");
-    let moreData = await new Promise(resolve => resolve(data));
+    let moreData = yield new Promise(resolve => resolve(data));
     // Ensure it handles more than one yield
-    moreData = await new Promise(resolve => resolve(data));
+    moreData = yield new Promise(resolve => resolve(data));
     dispatch({ type: "fetch1", data: moreData });
   };
 }
diff --git a/devtools/client/shared/redux/middleware/test/test_middleware-task-02.js b/devtools/client/shared/redux/middleware/test/test_middleware-task-02.js
index 5b00d0c80661..a7cb07114d99 100644
--- a/devtools/client/shared/redux/middleware/test/test_middleware-task-02.js
+++ b/devtools/client/shared/redux/middleware/test/test_middleware-task-02.js
@@ -16,11 +16,11 @@ function run_test() {
   run_next_test();
 }
 
-add_task(async function () {
+add_task(function* () {
   let store = applyMiddleware(task)(createStore)(reducer);
 
   store.dispatch(comboAction());
-  await waitUntilState(store, () => store.getState().length === 3);
+  yield waitUntilState(store, () => store.getState().length === 3);
 
   equal(store.getState()[0].type, "fetchAsync-start",
         "Async dispatched actions in a generator task are fired");
@@ -37,10 +37,10 @@ add_task(async function () {
 });
 
 function comboAction() {
-  return async function (dispatch, getState) {
+  return function* (dispatch, getState) {
     let data = {};
-    data.async = await dispatch(fetchAsync("async"));
-    data.sync = await dispatch(fetchSync("sync"));
+    data.async = yield dispatch(fetchAsync("async"));
+    data.sync = yield dispatch(fetchSync("sync"));
     dispatch({ type: "fetch-done", data });
   };
 }
@@ -50,9 +50,9 @@ function fetchSync(data) {
 }
 
 function fetchAsync(data) {
-  return async function (dispatch) {
+  return function* (dispatch) {
     dispatch({ type: "fetchAsync-start" });
-    let val = await new Promise(resolve => resolve(data));
+    let val = yield new Promise(resolve => resolve(data));
     dispatch({ type: "fetchAsync-end" });
     return val;
   };
diff --git a/devtools/client/shared/redux/middleware/test/test_middleware-task-03.js b/devtools/client/shared/redux/middleware/test/test_middleware-task-03.js
index a0d4733db570..03c022188527 100644
--- a/devtools/client/shared/redux/middleware/test/test_middleware-task-03.js
+++ b/devtools/client/shared/redux/middleware/test/test_middleware-task-03.js
@@ -15,11 +15,11 @@ function run_test() {
   run_next_test();
 }
 
-add_task(async function () {
+add_task(function* () {
   let store = applyMiddleware(task)(createStore)(reducer);
 
   store.dispatch(generatorError());
-  await waitUntilState(store, () => store.getState().length === 1);
+  yield waitUntilState(store, () => store.getState().length === 1);
   equal(store.getState()[0].type, ERROR_TYPE,
         "generator errors dispatch ERROR_TYPE actions");
   equal(store.getState()[0].error, "task-middleware-error-generator",
diff --git a/devtools/client/shared/test/browser_css_angle.js b/devtools/client/shared/test/browser_css_angle.js
index 712e626b76bd..42dcd6f4e81f 100644
--- a/devtools/client/shared/test/browser_css_angle.js
+++ b/devtools/client/shared/test/browser_css_angle.js
@@ -6,9 +6,9 @@
 
 var {angleUtils} = require("devtools/client/shared/css-angle");
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [host] = await createHost("bottom");
+add_task(function* () {
+  yield addTab("about:blank");
+  let [host] = yield createHost("bottom");
 
   info("Starting the test");
   testAngleUtils();
diff --git a/devtools/client/shared/test/browser_css_color.js b/devtools/client/shared/test/browser_css_color.js
index e31d7c8e1612..fbba3cfa07bc 100644
--- a/devtools/client/shared/test/browser_css_color.js
+++ b/devtools/client/shared/test/browser_css_color.js
@@ -7,9 +7,9 @@ var {colorUtils} = require("devtools/shared/css/color");
 /* global getFixtureColorData */
 loadHelperScript("helper_color_data.js");
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [host,, doc] = await createHost("bottom");
+add_task(function* () {
+  yield addTab("about:blank");
+  let [host,, doc] = yield createHost("bottom");
 
   info("Creating a test canvas element to test colors");
   let canvas = createTestCanvas(doc);
diff --git a/devtools/client/shared/test/browser_cubic-bezier-01.js b/devtools/client/shared/test/browser_cubic-bezier-01.js
index 647d54ea4504..9c9e5d219548 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-01.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-01.js
@@ -11,8 +11,8 @@ const {CubicBezierWidget} =
 
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-01.html";
 
-add_task(async function () {
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Checking that the graph markup is created in the parent");
   let container = doc.querySelector("#cubic-bezier-container");
diff --git a/devtools/client/shared/test/browser_cubic-bezier-02.js b/devtools/client/shared/test/browser_cubic-bezier-02.js
index d2c98482b24c..fc4e26263752 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-02.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-02.js
@@ -14,8 +14,8 @@ const {PREDEFINED} = require("devtools/client/shared/widgets/CubicBezierPresets"
 // in order to remove its margin and prevent shifted positions
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-02.html";
 
-add_task(async function () {
-  let [host, win, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host, win, doc] = yield createHost("bottom", TEST_URI);
 
   // Required or widget will be clipped inside of 'bottom'
   // host by -14. Setting `fixed` zeroes this which is needed for
@@ -30,15 +30,15 @@ add_task(async function () {
   rect.graphBottom = rect.height - rect.graphTop;
   rect.graphHeight = rect.graphBottom - rect.graphTop;
 
-  await pointsCanBeDragged(w, win, doc, rect);
-  await curveCanBeClicked(w, win, doc, rect);
-  await pointsCanBeMovedWithKeyboard(w, win, doc, rect);
+  yield pointsCanBeDragged(w, win, doc, rect);
+  yield curveCanBeClicked(w, win, doc, rect);
+  yield pointsCanBeMovedWithKeyboard(w, win, doc, rect);
 
   w.destroy();
   host.destroy();
 });
 
-async function pointsCanBeDragged(widget, win, doc, offsets) {
+function* pointsCanBeDragged(widget, win, doc, offsets) {
   info("Checking that the control points can be dragged with the mouse");
 
   info("Listening for the update event");
@@ -49,7 +49,7 @@ async function pointsCanBeDragged(widget, win, doc, offsets) {
   doc.onmousemove({pageX: offsets.left, pageY: offsets.graphTop});
   doc.onmouseup();
 
-  let bezier = await onUpdated;
+  let bezier = yield onUpdated;
   ok(true, "The widget fired the updated event");
   ok(bezier, "The updated event contains a bezier argument");
   is(bezier.P1[0], 0, "The new P1 time coordinate is correct");
@@ -63,12 +63,12 @@ async function pointsCanBeDragged(widget, win, doc, offsets) {
   doc.onmousemove({pageX: offsets.right, pageY: offsets.graphBottom});
   doc.onmouseup();
 
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P2[0], 1, "The new P2 time coordinate is correct");
   is(bezier.P2[1], 0, "The new P2 progress coordinate is correct");
 }
 
-async function curveCanBeClicked(widget, win, doc, offsets) {
+function* curveCanBeClicked(widget, win, doc, offsets) {
   info("Checking that clicking on the curve moves the closest control point");
 
   info("Listening for the update event");
@@ -79,7 +79,7 @@ async function curveCanBeClicked(widget, win, doc, offsets) {
   let y = offsets.graphTop + (offsets.graphHeight / 4.0);
   widget._onCurveClick({pageX: x, pageY: y});
 
-  let bezier = await onUpdated;
+  let bezier = yield onUpdated;
   ok(true, "The widget fired the updated event");
   is(bezier.P1[0], 0.25, "The new P1 time coordinate is correct");
   is(bezier.P1[1], 0.75, "The new P1 progress coordinate is correct");
@@ -94,14 +94,14 @@ async function curveCanBeClicked(widget, win, doc, offsets) {
   y = offsets.graphBottom - (offsets.graphHeight / 4);
   widget._onCurveClick({pageX: x, pageY: y});
 
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P2[0], 0.75, "The new P2 time coordinate is correct");
   is(bezier.P2[1], 0.25, "The new P2 progress coordinate is correct");
   is(bezier.P1[0], 0.25, "P1 time coordinate remained unchanged");
   is(bezier.P1[1], 0.75, "P1 progress coordinate remained unchanged");
 }
 
-async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
+function* pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
   info("Checking that points respond to keyboard events");
 
   let singleStep = 3;
@@ -114,7 +114,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   let onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p1, 37));
-  let bezier = await onUpdated;
+  let bezier = yield onUpdated;
 
   is(bezier.P1[0], x, "The new P1 time coordinate is correct");
   is(bezier.P1[1], 0.75, "The new P1 progress coordinate is correct");
@@ -126,7 +126,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p1, 37, true));
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P1[0], x, "The new P1 time coordinate is correct");
   is(bezier.P1[1], 0.75, "The new P1 progress coordinate is correct");
 
@@ -137,7 +137,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p1, 39, true));
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P1[0], x, "The new P1 time coordinate is correct");
   is(bezier.P1[1], 0.75, "The new P1 progress coordinate is correct");
 
@@ -148,7 +148,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p1, 40));
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P1[0], x, "The new P1 time coordinate is correct");
   is(bezier.P1[1], y, "The new P1 progress coordinate is correct");
 
@@ -159,7 +159,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p1, 40, true));
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P1[0], x, "The new P1 time coordinate is correct");
   is(bezier.P1[1], y, "The new P1 progress coordinate is correct");
 
@@ -170,7 +170,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p1, 38, true));
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P1[0], x, "The new P1 time coordinate is correct");
   is(bezier.P1[1], y, "The new P1 progress coordinate is correct");
 
@@ -182,7 +182,7 @@ async function pointsCanBeMovedWithKeyboard(widget, win, doc, offsets) {
 
   onUpdated = widget.once("updated");
   widget._onPointKeyDown(getKeyEvent(widget.p2, 37));
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   is(bezier.P2[0], x, "The new P2 time coordinate is correct");
   is(bezier.P2[1], 0.25, "The new P2 progress coordinate is correct");
 }
diff --git a/devtools/client/shared/test/browser_cubic-bezier-03.js b/devtools/client/shared/test/browser_cubic-bezier-03.js
index 1664e15d9a0d..a28e94d1ff32 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-03.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-03.js
@@ -12,27 +12,27 @@ const {PREDEFINED} = require("devtools/client/shared/widgets/CubicBezierPresets"
 
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-01.html";
 
-add_task(async function () {
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let container = doc.querySelector("#cubic-bezier-container");
   let w = new CubicBezierWidget(container, PREDEFINED.linear);
 
-  await coordinatesCanBeChangedByProvidingAnArray(w);
-  await coordinatesCanBeChangedByProvidingAValue(w);
+  yield coordinatesCanBeChangedByProvidingAnArray(w);
+  yield coordinatesCanBeChangedByProvidingAValue(w);
 
   w.destroy();
   host.destroy();
 });
 
-async function coordinatesCanBeChangedByProvidingAnArray(widget) {
+function* coordinatesCanBeChangedByProvidingAnArray(widget) {
   info("Listening for the update event");
   let onUpdated = widget.once("updated");
 
   info("Setting new coordinates");
   widget.coordinates = [0, 1, 1, 0];
 
-  let bezier = await onUpdated;
+  let bezier = yield onUpdated;
   ok(true, "The updated event was fired as a result of setting coordinates");
 
   is(bezier.P1[0], 0, "The new P1 time coordinate is correct");
@@ -41,13 +41,13 @@ async function coordinatesCanBeChangedByProvidingAnArray(widget) {
   is(bezier.P2[1], 0, "The new P2 progress coordinate is correct");
 }
 
-async function coordinatesCanBeChangedByProvidingAValue(widget) {
+function* coordinatesCanBeChangedByProvidingAValue(widget) {
   info("Listening for the update event");
   let onUpdated = widget.once("updated");
 
   info("Setting linear css value");
   widget.cssCubicBezierValue = "linear";
-  let bezier = await onUpdated;
+  let bezier = yield onUpdated;
   ok(true, "The updated event was fired as a result of setting cssValue");
 
   is(bezier.P1[0], 0, "The new P1 time coordinate is correct");
@@ -58,7 +58,7 @@ async function coordinatesCanBeChangedByProvidingAValue(widget) {
   info("Setting a custom cubic-bezier css value");
   onUpdated = widget.once("updated");
   widget.cssCubicBezierValue = "cubic-bezier(.25,-0.5, 1, 1.25)";
-  bezier = await onUpdated;
+  bezier = yield onUpdated;
   ok(true, "The updated event was fired as a result of setting cssValue");
 
   is(bezier.P1[0], .25, "The new P1 time coordinate is correct");
diff --git a/devtools/client/shared/test/browser_cubic-bezier-04.js b/devtools/client/shared/test/browser_cubic-bezier-04.js
index 8020a82951bc..b96c5de429b8 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-04.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-04.js
@@ -12,8 +12,8 @@ const {PRESETS} = require("devtools/client/shared/widgets/CubicBezierPresets");
 
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-01.html";
 
-add_task(async function () {
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let container = doc.querySelector("#cubic-bezier-container");
   let w = new CubicBezierPresetWidget(container);
diff --git a/devtools/client/shared/test/browser_cubic-bezier-05.js b/devtools/client/shared/test/browser_cubic-bezier-05.js
index ee2327ab8407..cbf0345021a6 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-05.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-05.js
@@ -13,8 +13,8 @@ const {PREDEFINED, PRESETS, DEFAULT_PRESET_CATEGORY} =
 
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-01.html";
 
-add_task(async function () {
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let container = doc.querySelector("#cubic-bezier-container");
   let w = new CubicBezierPresetWidget(container);
diff --git a/devtools/client/shared/test/browser_cubic-bezier-06.js b/devtools/client/shared/test/browser_cubic-bezier-06.js
index af0b2890f963..285574875ea4 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-06.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-06.js
@@ -13,8 +13,8 @@ const {PRESETS} = require("devtools/client/shared/widgets/CubicBezierPresets");
 
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-01.html";
 
-add_task(async function () {
-  let [host, win, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host, win, doc] = yield createHost("bottom", TEST_URI);
 
   let container = doc.querySelector("#cubic-bezier-container");
   let w = new CubicBezierWidget(container,
@@ -24,14 +24,14 @@ add_task(async function () {
   let rect = w.curve.getBoundingClientRect();
   rect.graphTop = rect.height * w.bezierCanvas.padding[0];
 
-  await adjustingBezierUpdatesPreset(w, win, doc, rect);
-  await selectingPresetUpdatesBezier(w, win, doc, rect);
+  yield adjustingBezierUpdatesPreset(w, win, doc, rect);
+  yield selectingPresetUpdatesBezier(w, win, doc, rect);
 
   w.destroy();
   host.destroy();
 });
 
-function adjustingBezierUpdatesPreset(widget, win, doc, rect) {
+function* adjustingBezierUpdatesPreset(widget, win, doc, rect) {
   info("Checking that changing the bezier refreshes the preset menu");
 
   is(widget.presets.activeCategory,
@@ -55,7 +55,7 @@ function adjustingBezierUpdatesPreset(widget, win, doc, rect) {
      "There is no active preset");
 }
 
-async function selectingPresetUpdatesBezier(widget, win, doc, rect) {
+function* selectingPresetUpdatesBezier(widget, win, doc, rect) {
   info("Checking that selecting a preset updates bezier curve");
 
   info("Listening for the new coordinates event");
@@ -66,10 +66,10 @@ async function selectingPresetUpdatesBezier(widget, win, doc, rect) {
   let preset = doc.querySelector("#ease-in-sine");
   widget.presets._onPresetClick({currentTarget: preset});
 
-  await onNewCoordinates;
+  yield onNewCoordinates;
   ok(true, "The preset widget fired the new-coordinates event");
 
-  let bezier = await onUpdated;
+  let bezier = yield onUpdated;
   ok(true, "The bezier canvas fired the updated event");
 
   is(bezier.P1[0], preset.coordinates[0], "The new P1 time coordinate is correct");
diff --git a/devtools/client/shared/test/browser_cubic-bezier-07.js b/devtools/client/shared/test/browser_cubic-bezier-07.js
index 7962b27feeaf..2f1ba186e685 100644
--- a/devtools/client/shared/test/browser_cubic-bezier-07.js
+++ b/devtools/client/shared/test/browser_cubic-bezier-07.js
@@ -12,26 +12,26 @@ const {PREDEFINED} = require("devtools/client/shared/widgets/CubicBezierPresets"
 
 const TEST_URI = CHROME_URL_ROOT + "doc_cubic-bezier-01.html";
 
-add_task(async function () {
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let container = doc.querySelector("#cubic-bezier-container");
   let w = new CubicBezierWidget(container, PREDEFINED.linear);
 
-  await previewDotReactsToChanges(w, [0.6, -0.28, 0.74, 0.05]);
-  await previewDotReactsToChanges(w, [0.9, 0.03, 0.69, 0.22]);
-  await previewDotReactsToChanges(w, [0.68, -0.55, 0.27, 1.55]);
-  await previewDotReactsToChanges(w, PREDEFINED.ease, "ease");
-  await previewDotReactsToChanges(w, PREDEFINED["ease-in-out"], "ease-in-out");
+  yield previewDotReactsToChanges(w, [0.6, -0.28, 0.74, 0.05]);
+  yield previewDotReactsToChanges(w, [0.9, 0.03, 0.69, 0.22]);
+  yield previewDotReactsToChanges(w, [0.68, -0.55, 0.27, 1.55]);
+  yield previewDotReactsToChanges(w, PREDEFINED.ease, "ease");
+  yield previewDotReactsToChanges(w, PREDEFINED["ease-in-out"], "ease-in-out");
 
   w.destroy();
   host.destroy();
 });
 
-async function previewDotReactsToChanges(widget, coords, expectedEasing) {
+function* previewDotReactsToChanges(widget, coords, expectedEasing) {
   let onUpdated = widget.once("updated");
   widget.coordinates = coords;
-  await onUpdated;
+  yield onUpdated;
 
   let animatedDot = widget.timingPreview.dot;
   let animations = animatedDot.getAnimations();
diff --git a/devtools/client/shared/test/browser_devices.js b/devtools/client/shared/test/browser_devices.js
index 51953d9f7d46..0bf52fe8e9cf 100644
--- a/devtools/client/shared/test/browser_devices.js
+++ b/devtools/client/shared/test/browser_devices.js
@@ -9,11 +9,11 @@ const {
   addDevice
 } = require("devtools/client/shared/devices");
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setCharPref("devtools.devices.url",
                              TEST_URI_ROOT + "browser_devices.json");
 
-  let devices = await getDevices();
+  let devices = yield getDevices();
 
   is(devices.TYPES.length, 1, "Found 1 device type.");
 
@@ -34,7 +34,7 @@ add_task(async function () {
     firefoxOS: true
   };
   addDevice(device1, type1);
-  devices = await getDevices();
+  devices = yield getDevices();
 
   is(devices[type1].length, 3, "Added new device of type #1.");
   ok(devices[type1].filter(d => d.name === device1.name), "Found the new device.");
@@ -50,7 +50,7 @@ add_task(async function () {
     firefoxOS: true
   };
   addDevice(device2, type2);
-  devices = await getDevices();
+  devices = yield getDevices();
 
   is(devices.TYPES.length, 2, "Added device type #2.");
   is(devices[type2].length, 1, "Added new device of type #2.");
diff --git a/devtools/client/shared/test/browser_filter-editor-01.js b/devtools/client/shared/test/browser_filter-editor-01.js
index 01fbe7814667..c8baa6de25b4 100644
--- a/devtools/client/shared/test/browser_filter-editor-01.js
+++ b/devtools/client/shared/test/browser_filter-editor-01.js
@@ -24,8 +24,8 @@ function verifyURL(string) {
   return lexer.nextToken() === null;
 }
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-02.js b/devtools/client/shared/test/browser_filter-editor-02.js
index 23a599432fb0..d230306087db 100644
--- a/devtools/client/shared/test/browser_filter-editor-02.js
+++ b/devtools/client/shared/test/browser_filter-editor-02.js
@@ -14,8 +14,8 @@ const L10N = new LocalizationHelper(STRINGS_URI);
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const TEST_DATA = [
diff --git a/devtools/client/shared/test/browser_filter-editor-03.js b/devtools/client/shared/test/browser_filter-editor-03.js
index 62a2037a0c34..34bdf358068f 100644
--- a/devtools/client/shared/test/browser_filter-editor-03.js
+++ b/devtools/client/shared/test/browser_filter-editor-03.js
@@ -12,8 +12,8 @@ const INVERT_MIN = 0;
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-04.js b/devtools/client/shared/test/browser_filter-editor-04.js
index 54e504c57805..22f6cfc76b47 100644
--- a/devtools/client/shared/test/browser_filter-editor-04.js
+++ b/devtools/client/shared/test/browser_filter-editor-04.js
@@ -11,8 +11,8 @@ const LIST_ITEM_HEIGHT = 32;
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-05.js b/devtools/client/shared/test/browser_filter-editor-05.js
index 33364cfe244c..6df4111bfc5a 100644
--- a/devtools/client/shared/test/browser_filter-editor-05.js
+++ b/devtools/client/shared/test/browser_filter-editor-05.js
@@ -19,8 +19,8 @@ const GRAYSCALE_MAX = 100,
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-06.js b/devtools/client/shared/test/browser_filter-editor-06.js
index 91d12d535a56..6c8e2bd18bc7 100644
--- a/devtools/client/shared/test/browser_filter-editor-06.js
+++ b/devtools/client/shared/test/browser_filter-editor-06.js
@@ -14,8 +14,8 @@ const L10N = new LocalizationHelper(STRINGS_URI);
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-07.js b/devtools/client/shared/test/browser_filter-editor-07.js
index 3b439f03a532..c965e6d24eb7 100644
--- a/devtools/client/shared/test/browser_filter-editor-07.js
+++ b/devtools/client/shared/test/browser_filter-editor-07.js
@@ -10,8 +10,8 @@ const {getClientCssProperties} = require("devtools/shared/fronts/css-properties"
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-08.js b/devtools/client/shared/test/browser_filter-editor-08.js
index 2f413fda7ea7..59b5d1562510 100644
--- a/devtools/client/shared/test/browser_filter-editor-08.js
+++ b/devtools/client/shared/test/browser_filter-editor-08.js
@@ -15,8 +15,8 @@ const DEFAULT_VALUE_MULTIPLIER = 1;
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-09.js b/devtools/client/shared/test/browser_filter-editor-09.js
index 4c4f6615cd39..b167d20740ae 100644
--- a/devtools/client/shared/test/browser_filter-editor-09.js
+++ b/devtools/client/shared/test/browser_filter-editor-09.js
@@ -15,8 +15,8 @@ const DEFAULT_VALUE_MULTIPLIER = 1;
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-editor-10.js b/devtools/client/shared/test/browser_filter-editor-10.js
index f3d6650e8c91..09e14dbfb697 100644
--- a/devtools/client/shared/test/browser_filter-editor-10.js
+++ b/devtools/client/shared/test/browser_filter-editor-10.js
@@ -13,8 +13,8 @@ const DEFAULT_VALUE_MULTIPLIER = 1;
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
diff --git a/devtools/client/shared/test/browser_filter-presets-01.js b/devtools/client/shared/test/browser_filter-presets-01.js
index b41dafa3e0f0..65f048b62da0 100644
--- a/devtools/client/shared/test/browser_filter-presets-01.js
+++ b/devtools/client/shared/test/browser_filter-presets-01.js
@@ -10,19 +10,19 @@ const {getClientCssProperties} = require("devtools/shared/fronts/css-properties"
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
   let widget = new CSSFilterEditorWidget(container, "none", cssIsValid);
   // First render
-  await widget.once("render");
+  yield widget.once("render");
 
   const VALUE = "blur(2px) contrast(150%)";
   const NAME = "Test";
 
-  await showFilterPopupPresetsAndCreatePreset(widget, NAME, VALUE);
+  yield showFilterPopupPresetsAndCreatePreset(widget, NAME, VALUE);
 
   let preset = widget.el.querySelector(".preset");
   is(preset.querySelector("label").textContent, NAME,
@@ -30,7 +30,7 @@ add_task(async function () {
   is(preset.querySelector("span").textContent, VALUE,
      "Should show preset value preview correctly");
 
-  let list = await widget.getPresets();
+  let list = yield widget.getPresets();
   let input = widget.el.querySelector(".presets-list .footer input");
   let data = list[0];
 
@@ -45,12 +45,12 @@ add_task(async function () {
 
   widget.setCssValue(VALUE_2);
 
-  await savePreset(widget);
+  yield savePreset(widget);
 
   is(widget.el.querySelectorAll(".preset").length, 1,
      "Should override the preset with the same name - render");
 
-  list = await widget.getPresets();
+  list = yield widget.getPresets();
   data = list[0];
 
   is(list.length, 1,
@@ -61,14 +61,14 @@ add_task(async function () {
   is(data.value, VALUE_2,
      "Should override the preset with the same name - prop value");
 
-  await widget.setPresets([]);
+  yield widget.setPresets([]);
 
   info("Test saving a preset without name");
   input.value = "";
 
-  await savePreset(widget, "preset-save-error");
+  yield savePreset(widget, "preset-save-error");
 
-  list = await widget.getPresets();
+  list = yield widget.getPresets();
   is(list.length, 0,
      "Should not add a preset without name");
 
@@ -77,9 +77,9 @@ add_task(async function () {
   input.value = NAME;
   widget.setCssValue("none");
 
-  await savePreset(widget, "preset-save-error");
+  yield savePreset(widget, "preset-save-error");
 
-  list = await widget.getPresets();
+  list = yield widget.getPresets();
   is(list.length, 0,
      "Should not add a preset without filters (value: none)");
 });
diff --git a/devtools/client/shared/test/browser_filter-presets-02.js b/devtools/client/shared/test/browser_filter-presets-02.js
index 4119346c5f6d..9a063d3e750d 100644
--- a/devtools/client/shared/test/browser_filter-presets-02.js
+++ b/devtools/client/shared/test/browser_filter-presets-02.js
@@ -10,24 +10,24 @@ const {getClientCssProperties} = require("devtools/shared/fronts/css-properties"
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
   let widget = new CSSFilterEditorWidget(container, "none", cssIsValid);
   // First render
-  await widget.once("render");
+  yield widget.once("render");
 
   const VALUE = "blur(2px) contrast(150%)";
   const NAME = "Test";
 
-  await showFilterPopupPresetsAndCreatePreset(widget, NAME, VALUE);
+  yield showFilterPopupPresetsAndCreatePreset(widget, NAME, VALUE);
 
   let onRender = widget.once("render");
   // reset value
   widget.setCssValue("saturate(100%) brightness(150%)");
-  await onRender;
+  yield onRender;
 
   let preset = widget.el.querySelector(".preset");
 
@@ -36,7 +36,7 @@ add_task(async function () {
     target: preset
   });
 
-  await onRender;
+  yield onRender;
 
   is(widget.getCssValue(), VALUE,
      "Should set widget's value correctly");
diff --git a/devtools/client/shared/test/browser_filter-presets-03.js b/devtools/client/shared/test/browser_filter-presets-03.js
index 75ad970c8a0d..2672aff02b6c 100644
--- a/devtools/client/shared/test/browser_filter-presets-03.js
+++ b/devtools/client/shared/test/browser_filter-presets-03.js
@@ -10,19 +10,19 @@ const {getClientCssProperties} = require("devtools/shared/fronts/css-properties"
 
 const TEST_URI = CHROME_URL_ROOT + "doc_filter-editor-01.html";
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   const cssIsValid = getClientCssProperties().getValidityChecker(doc);
 
   const container = doc.querySelector("#filter-container");
   let widget = new CSSFilterEditorWidget(container, "none", cssIsValid);
   // First render
-  await widget.once("render");
+  yield widget.once("render");
 
   const NAME = "Test";
   const VALUE = "blur(2px) contrast(150%)";
 
-  await showFilterPopupPresetsAndCreatePreset(widget, NAME, VALUE);
+  yield showFilterPopupPresetsAndCreatePreset(widget, NAME, VALUE);
 
   let removeButton = widget.el.querySelector(".preset .remove-button");
   let onRender = widget.once("render");
@@ -30,11 +30,11 @@ add_task(async function () {
     target: removeButton
   });
 
-  await onRender;
+  yield onRender;
   is(widget.el.querySelector(".preset"), null,
      "Should re-render after removing preset");
 
-  let list = await widget.getPresets();
+  let list = yield widget.getPresets();
   is(list.length, 0,
      "Should remove presets from asyncStorage");
 });
diff --git a/devtools/client/shared/test/browser_flame-graph-01.js b/devtools/client/shared/test/browser_flame-graph-01.js
index d49112647c39..a32fb9fd3710 100644
--- a/devtools/client/shared/test/browser_flame-graph-01.js
+++ b/devtools/client/shared/test/browser_flame-graph-01.js
@@ -7,14 +7,14 @@
 
 const {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -25,12 +25,12 @@ async function performTest() {
     readyEventEmitted = true;
   });
 
-  await graph.ready();
+  yield graph.ready();
   ok(readyEventEmitted, "The 'ready' event should have been emitted");
 
   testGraph(host, graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_flame-graph-02.js b/devtools/client/shared/test/browser_flame-graph-02.js
index 5f11c9a34fae..e15c3efe0876 100644
--- a/devtools/client/shared/test/browser_flame-graph-02.js
+++ b/devtools/client/shared/test/browser_flame-graph-02.js
@@ -7,14 +7,14 @@
 
 const {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -22,10 +22,10 @@ async function performTest() {
   graph.fixedWidth = 200;
   graph.fixedHeight = 100;
 
-  await graph.ready();
+  yield graph.ready();
   testGraph(host, graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_flame-graph-03a.js b/devtools/client/shared/test/browser_flame-graph-03a.js
index 95d5d01e8e82..2d8810a412da 100644
--- a/devtools/client/shared/test/browser_flame-graph-03a.js
+++ b/devtools/client/shared/test/browser_flame-graph-03a.js
@@ -26,14 +26,14 @@ const TEST_HEIGHT = 100;
 
 const {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -43,11 +43,11 @@ async function performTest() {
   graph.horizontalPanThreshold = 0;
   graph.verticalPanThreshold = 0;
 
-  await graph.ready();
+  yield graph.ready();
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_flame-graph-03b.js b/devtools/client/shared/test/browser_flame-graph-03b.js
index fd2421ce9222..26604ce9dd94 100644
--- a/devtools/client/shared/test/browser_flame-graph-03b.js
+++ b/devtools/client/shared/test/browser_flame-graph-03b.js
@@ -27,14 +27,14 @@ const TEST_DPI_DENSITIY = 2;
 
 var {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -42,11 +42,11 @@ async function performTest() {
   graph.fixedWidth = TEST_WIDTH;
   graph.fixedHeight = TEST_HEIGHT;
 
-  await graph.ready();
+  yield graph.ready();
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_flame-graph-03c.js b/devtools/client/shared/test/browser_flame-graph-03c.js
index e2bc132ddf78..3a6bf80ae26d 100644
--- a/devtools/client/shared/test/browser_flame-graph-03c.js
+++ b/devtools/client/shared/test/browser_flame-graph-03c.js
@@ -27,14 +27,14 @@ const TEST_DPI_DENSITIY = 2;
 
 const {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -42,11 +42,11 @@ async function performTest() {
   graph.fixedWidth = TEST_WIDTH;
   graph.fixedHeight = TEST_HEIGHT;
 
-  await graph.ready();
+  yield graph.ready();
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_flame-graph-04.js b/devtools/client/shared/test/browser_flame-graph-04.js
index a1197444e537..5bcc112ec4c9 100644
--- a/devtools/client/shared/test/browser_flame-graph-04.js
+++ b/devtools/client/shared/test/browser_flame-graph-04.js
@@ -11,20 +11,20 @@ const {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 const {FLAME_GRAPH_BLOCK_TEXT_FONT_SIZE} = require("devtools/client/shared/widgets/FlameGraph");
 const {FLAME_GRAPH_BLOCK_TEXT_FONT_FAMILY} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new FlameGraph(doc.body, 1);
-  await graph.ready();
+  yield graph.ready();
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_flame-graph-05.js b/devtools/client/shared/test/browser_flame-graph-05.js
index 95e61f25f60b..80e7df777a9a 100644
--- a/devtools/client/shared/test/browser_flame-graph-05.js
+++ b/devtools/client/shared/test/browser_flame-graph-05.js
@@ -30,27 +30,27 @@ const KEY_CODE_RIGHT = 39;
 
 var {FlameGraph} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
   let graph = new FlameGraph(doc.body, TEST_DPI_DENSITIY);
-  await graph.ready();
+  yield graph.ready();
 
-  await testGraph(host, graph);
+  yield testGraph(host, graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(host, graph) {
+function* testGraph(host, graph) {
   graph.setData({ data: TEST_DATA, bounds: TEST_BOUNDS });
 
   is(graph._selection.start, 0,
@@ -58,7 +58,7 @@ async function testGraph(host, graph) {
   is(graph._selection.end, TEST_BOUNDS.endTime * TEST_DPI_DENSITIY,
     "The graph's selection end value is initially correct.");
 
-  await pressKeyForTime(graph, KEY_CODE_LEFT, 1000);
+  yield pressKeyForTime(graph, KEY_CODE_LEFT, 1000);
 
   is(graph._selection.start, 0,
     "The graph's selection start value is correct after pressing LEFT.");
@@ -69,7 +69,7 @@ async function testGraph(host, graph) {
   graph._selection.end = TEST_BOUNDS.endTime * TEST_DPI_DENSITIY;
   info("Graph selection was reset (1).");
 
-  await pressKeyForTime(graph, KEY_CODE_RIGHT, 1000);
+  yield pressKeyForTime(graph, KEY_CODE_RIGHT, 1000);
 
   ok(graph._selection.start > 0,
     "The graph's selection start value is correct after pressing RIGHT.");
@@ -80,7 +80,7 @@ async function testGraph(host, graph) {
   graph._selection.end = TEST_BOUNDS.endTime * TEST_DPI_DENSITIY;
   info("Graph selection was reset (2).");
 
-  await pressKeyForTime(graph, KEY_CODE_UP, 1000);
+  yield pressKeyForTime(graph, KEY_CODE_UP, 1000);
 
   ok(graph._selection.start > 0,
     "The graph's selection start value is correct after pressing UP.");
diff --git a/devtools/client/shared/test/browser_flame-graph-utils-01.js b/devtools/client/shared/test/browser_flame-graph-utils-01.js
index 739591816725..6871e234cfb5 100644
--- a/devtools/client/shared/test/browser_flame-graph-utils-01.js
+++ b/devtools/client/shared/test/browser_flame-graph-utils-01.js
@@ -9,13 +9,13 @@
 const {FlameGraphUtils} = require("devtools/client/shared/widgets/FlameGraph");
 const {PALLETTE_SIZE} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-function performTest() {
+function* performTest() {
   let out = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA);
 
   ok(out, "Some data was outputted properly");
diff --git a/devtools/client/shared/test/browser_flame-graph-utils-02.js b/devtools/client/shared/test/browser_flame-graph-utils-02.js
index 3e6621deee83..15e9d19338fe 100644
--- a/devtools/client/shared/test/browser_flame-graph-utils-02.js
+++ b/devtools/client/shared/test/browser_flame-graph-utils-02.js
@@ -8,13 +8,13 @@
 const {FlameGraphUtils} = require("devtools/client/shared/widgets/FlameGraph");
 const {PALLETTE_SIZE} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-function performTest() {
+function* performTest() {
   let out = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA, {
     flattenRecursion: true
   });
diff --git a/devtools/client/shared/test/browser_flame-graph-utils-03.js b/devtools/client/shared/test/browser_flame-graph-utils-03.js
index 87a7e538ab0e..0f28c0afc991 100644
--- a/devtools/client/shared/test/browser_flame-graph-utils-03.js
+++ b/devtools/client/shared/test/browser_flame-graph-utils-03.js
@@ -8,13 +8,13 @@
 const {FlameGraphUtils} = require("devtools/client/shared/widgets/FlameGraph");
 const {PALLETTE_SIZE} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-function performTest() {
+function* performTest() {
   let out = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA, {
     contentOnly: true
   });
diff --git a/devtools/client/shared/test/browser_flame-graph-utils-04.js b/devtools/client/shared/test/browser_flame-graph-utils-04.js
index 6a957600d13d..1bf6c1f595d6 100644
--- a/devtools/client/shared/test/browser_flame-graph-utils-04.js
+++ b/devtools/client/shared/test/browser_flame-graph-utils-04.js
@@ -8,13 +8,13 @@
 const {FlameGraphUtils} = require("devtools/client/shared/widgets/FlameGraph");
 const {PALLETTE_SIZE} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-function performTest() {
+function* performTest() {
   let out = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA, {
     flattenRecursion: true,
     contentOnly: true,
diff --git a/devtools/client/shared/test/browser_flame-graph-utils-05.js b/devtools/client/shared/test/browser_flame-graph-utils-05.js
index dbc1118df441..5abdd708a901 100644
--- a/devtools/client/shared/test/browser_flame-graph-utils-05.js
+++ b/devtools/client/shared/test/browser_flame-graph-utils-05.js
@@ -7,13 +7,13 @@
 
 const {FlameGraphUtils} = require("devtools/client/shared/widgets/FlameGraph");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-function performTest() {
+function* performTest() {
   let out1 = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA);
   let out2 = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA);
   is(out1, out2, "The outputted data is identical.");
diff --git a/devtools/client/shared/test/browser_flame-graph-utils-06.js b/devtools/client/shared/test/browser_flame-graph-utils-06.js
index 4c3a7b3a7965..886a1035b882 100644
--- a/devtools/client/shared/test/browser_flame-graph-utils-06.js
+++ b/devtools/client/shared/test/browser_flame-graph-utils-06.js
@@ -11,13 +11,13 @@ const {PALLETTE_SIZE} = require("devtools/client/shared/widgets/FlameGraph");
 const MANGLED_FN = "__Z3FooIiEvv";
 const UNMANGLED_FN = "void Foo<int>()";
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-function performTest() {
+function* performTest() {
   let out = FlameGraphUtils.createFlameGraphDataFromThread(TEST_DATA, {
     flattenRecursion: true
   });
diff --git a/devtools/client/shared/test/browser_graphs-01.js b/devtools/client/shared/test/browser_graphs-01.js
index 4c882fc11341..c4f5640d90d1 100644
--- a/devtools/client/shared/test/browser_graphs-01.js
+++ b/devtools/client/shared/test/browser_graphs-01.js
@@ -7,15 +7,15 @@
 
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
   finish();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -26,12 +26,12 @@ async function performTest() {
     readyEventEmitted = true;
   });
 
-  await graph.ready();
+  yield graph.ready();
   ok(readyEventEmitted, "The 'ready' event should have been emitted");
 
   testGraph(host, graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-02.js b/devtools/client/shared/test/browser_graphs-02.js
index c86754e80cb7..def7287227ab 100644
--- a/devtools/client/shared/test/browser_graphs-02.js
+++ b/devtools/client/shared/test/browser_graphs-02.js
@@ -30,21 +30,21 @@ const TEST_DATA = [
 const TEST_REGIONS = [{ start: 320, end: 460 }, { start: 780, end: 860 }];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testDataAndRegions(graph);
   testHighlights(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-03.js b/devtools/client/shared/test/browser_graphs-03.js
index 757f4868c211..b44d4620ac46 100644
--- a/devtools/client/shared/test/browser_graphs-03.js
+++ b/devtools/client/shared/test/browser_graphs-03.js
@@ -8,25 +8,25 @@
 
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
-  await testSelection(graph);
-  await testCursor(graph);
+  yield testSelection(graph);
+  yield testCursor(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testSelection(graph) {
+function* testSelection(graph) {
   ok(graph.getSelection().start === null,
     "The graph's selection should initially have a null start value.");
   ok(graph.getSelection().end === null,
@@ -37,7 +37,7 @@ async function testSelection(graph) {
   let selected = graph.once("selecting");
   graph.setSelection({ start: 100, end: 200 });
 
-  await selected;
+  yield selected;
   ok(true, "A 'selecting' event has been fired.");
 
   ok(graph.hasSelection(),
@@ -61,7 +61,7 @@ async function testSelection(graph) {
   let deselected = graph.once("deselecting");
   graph.dropSelection();
 
-  await deselected;
+  yield deselected;
   ok(true, "A 'deselecting' event has been fired.");
 
   ok(!graph.hasSelection(),
@@ -72,7 +72,7 @@ async function testSelection(graph) {
     "The graph's selection now has a null end value.");
 }
 
-function testCursor(graph) {
+function* testCursor(graph) {
   ok(graph.getCursor().x === null,
     "The graph's cursor should initially have a null X value.");
   ok(graph.getCursor().y === null,
diff --git a/devtools/client/shared/test/browser_graphs-04.js b/devtools/client/shared/test/browser_graphs-04.js
index 7ecf8ce50448..452b27c4a127 100644
--- a/devtools/client/shared/test/browser_graphs-04.js
+++ b/devtools/client/shared/test/browser_graphs-04.js
@@ -7,20 +7,20 @@
 
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-05.js b/devtools/client/shared/test/browser_graphs-05.js
index 1e63a1eacff0..bd3da912884d 100644
--- a/devtools/client/shared/test/browser_graphs-05.js
+++ b/devtools/client/shared/test/browser_graphs-05.js
@@ -30,20 +30,20 @@ const TEST_DATA = [
 const TEST_REGIONS = [{ start: 320, end: 460 }, { start: 780, end: 860 }];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-06.js b/devtools/client/shared/test/browser_graphs-06.js
index ee94ac4856f1..596fe7702527 100644
--- a/devtools/client/shared/test/browser_graphs-06.js
+++ b/devtools/client/shared/test/browser_graphs-06.js
@@ -30,20 +30,20 @@ const TEST_DATA = [
 const TEST_REGIONS = [{ start: 320, end: 460 }, { start: 780, end: 860 }];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-07a.js b/devtools/client/shared/test/browser_graphs-07a.js
index dd47dbf4c207..44e166cc53bb 100644
--- a/devtools/client/shared/test/browser_graphs-07a.js
+++ b/devtools/client/shared/test/browser_graphs-07a.js
@@ -29,23 +29,23 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
   testGraph(graph, normalDragStop);
-  await graph.destroy();
+  yield graph.destroy();
 
   let graph2 = new LineGraphWidget(doc.body, "fps");
-  await graph2.once("ready");
+  yield graph2.once("ready");
   testGraph(graph2, buggyDragStop);
-  await graph2.destroy();
+  yield graph2.destroy();
 
   host.destroy();
 }
diff --git a/devtools/client/shared/test/browser_graphs-07b.js b/devtools/client/shared/test/browser_graphs-07b.js
index 9a3e9e75fd27..3b4bc5740db8 100644
--- a/devtools/client/shared/test/browser_graphs-07b.js
+++ b/devtools/client/shared/test/browser_graphs-07b.js
@@ -29,20 +29,20 @@ const TEST_DATA = [
 ];
 var LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-07c.js b/devtools/client/shared/test/browser_graphs-07c.js
index 64f789f066c4..1791ced120f1 100644
--- a/devtools/client/shared/test/browser_graphs-07c.js
+++ b/devtools/client/shared/test/browser_graphs-07c.js
@@ -31,18 +31,18 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
   testGraph(graph);
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-07d.js b/devtools/client/shared/test/browser_graphs-07d.js
index e3f7756da750..8a64f7d75a29 100644
--- a/devtools/client/shared/test/browser_graphs-07d.js
+++ b/devtools/client/shared/test/browser_graphs-07d.js
@@ -30,20 +30,20 @@ const TEST_DATA = [
 const TEST_REGIONS = [{ start: 320, end: 460 }, { start: 780, end: 860 }];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-07e.js b/devtools/client/shared/test/browser_graphs-07e.js
index c294b925dbc3..814284b9de7f 100644
--- a/devtools/client/shared/test/browser_graphs-07e.js
+++ b/devtools/client/shared/test/browser_graphs-07e.js
@@ -30,16 +30,16 @@ const TEST_DATA = [
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 let CURRENT_ZOOM = 1;
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
   graph.setData(TEST_DATA);
 
   info("Testing with normal zoom.");
@@ -53,7 +53,7 @@ async function performTest() {
   setZoom(host.frame, 2);
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-08.js b/devtools/client/shared/test/browser_graphs-08.js
index 280cd2a60783..ae6b54fb58b5 100644
--- a/devtools/client/shared/test/browser_graphs-08.js
+++ b/devtools/client/shared/test/browser_graphs-08.js
@@ -29,20 +29,20 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-09a.js b/devtools/client/shared/test/browser_graphs-09a.js
index 57b89f57409b..8e6e65c242ef 100644
--- a/devtools/client/shared/test/browser_graphs-09a.js
+++ b/devtools/client/shared/test/browser_graphs-09a.js
@@ -29,26 +29,26 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, { metric: "fps" });
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
+function* testGraph(graph) {
   info("Should be able to set the graph data before waiting for the ready event.");
 
-  await graph.setDataWhenReady(TEST_DATA);
+  yield graph.setDataWhenReady(TEST_DATA);
   ok(graph.hasData(), "Data was set successfully.");
 
   is(graph._gutter.hidden, false,
diff --git a/devtools/client/shared/test/browser_graphs-09b.js b/devtools/client/shared/test/browser_graphs-09b.js
index 27faf981fb5e..58dc552fb876 100644
--- a/devtools/client/shared/test/browser_graphs-09b.js
+++ b/devtools/client/shared/test/browser_graphs-09b.js
@@ -29,26 +29,26 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
   graph.withTooltipArrows = false;
   graph.withFixedTooltipPositions = true;
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
-  await graph.setDataWhenReady(TEST_DATA);
+function* testGraph(graph) {
+  yield graph.setDataWhenReady(TEST_DATA);
 
   is(graph._gutter.hidden, false,
     "The gutter should be visible even if the tooltips don't have arrows.");
diff --git a/devtools/client/shared/test/browser_graphs-09c.js b/devtools/client/shared/test/browser_graphs-09c.js
index 74c4e1fbc934..ba3d3c1c4411 100644
--- a/devtools/client/shared/test/browser_graphs-09c.js
+++ b/devtools/client/shared/test/browser_graphs-09c.js
@@ -8,24 +8,24 @@
 const TEST_DATA = [];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
-  await graph.setDataWhenReady(TEST_DATA);
+function* testGraph(graph) {
+  yield graph.setDataWhenReady(TEST_DATA);
 
   is(graph._gutter.hidden, true,
     "The gutter should be hidden, since there's no data available.");
diff --git a/devtools/client/shared/test/browser_graphs-09d.js b/devtools/client/shared/test/browser_graphs-09d.js
index 1109f485e6a4..7d0c01c15f68 100644
--- a/devtools/client/shared/test/browser_graphs-09d.js
+++ b/devtools/client/shared/test/browser_graphs-09d.js
@@ -9,24 +9,24 @@
 const TEST_DATA = [{ delta: 100, value: 60 }, { delta: 200, value: 59.9 }];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
-  await graph.setDataWhenReady(TEST_DATA);
+function* testGraph(graph) {
+  yield graph.setDataWhenReady(TEST_DATA);
 
   is(graph._gutter.hidden, false,
     "The gutter should not be hidden.");
diff --git a/devtools/client/shared/test/browser_graphs-09e.js b/devtools/client/shared/test/browser_graphs-09e.js
index a73abe42494e..72f2f7bdd1bd 100644
--- a/devtools/client/shared/test/browser_graphs-09e.js
+++ b/devtools/client/shared/test/browser_graphs-09e.js
@@ -32,24 +32,24 @@ const TEST_DATA = [
 
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
-  await graph.setDataWhenReady(NO_DATA);
+function* testGraph(graph) {
+  yield graph.setDataWhenReady(NO_DATA);
 
   is(graph._gutter.hidden, true,
     "The gutter should be hidden when there's no data available.");
@@ -60,7 +60,7 @@ async function testGraph(graph) {
   is(graph._minTooltip.hidden, true,
     "The min tooltip should be hidden when there's no data available.");
 
-  await graph.setDataWhenReady(TEST_DATA);
+  yield graph.setDataWhenReady(TEST_DATA);
 
   is(graph._gutter.hidden, false,
     "The gutter should be visible now.");
@@ -71,7 +71,7 @@ async function testGraph(graph) {
   is(graph._minTooltip.hidden, false,
     "The min tooltip should be visible now.");
 
-  await graph.setDataWhenReady(NO_DATA);
+  yield graph.setDataWhenReady(NO_DATA);
 
   is(graph._gutter.hidden, true,
     "The gutter should be hidden again.");
diff --git a/devtools/client/shared/test/browser_graphs-09f.js b/devtools/client/shared/test/browser_graphs-09f.js
index 0b32675d88dd..32b5819b2552 100644
--- a/devtools/client/shared/test/browser_graphs-09f.js
+++ b/devtools/client/shared/test/browser_graphs-09f.js
@@ -9,28 +9,28 @@
 const TEST_DATA = [{ delta: 100, value: 60 }, { delta: 200, value: 1 }];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
 
-  await testGraph(doc.body, { avg: false });
-  await testGraph(doc.body, { min: false });
-  await testGraph(doc.body, { max: false });
-  await testGraph(doc.body, { min: false, max: false, avg: false });
-  await testGraph(doc.body, {});
+  yield testGraph(doc.body, { avg: false });
+  yield testGraph(doc.body, { min: false });
+  yield testGraph(doc.body, { max: false });
+  yield testGraph(doc.body, { min: false, max: false, avg: false });
+  yield testGraph(doc.body, {});
 
   host.destroy();
 }
 
-async function testGraph(parent, options) {
+function* testGraph(parent, options) {
   options.metric = "fps";
   let graph = new LineGraphWidget(parent, options);
-  await graph.setDataWhenReady(TEST_DATA);
+  yield graph.setDataWhenReady(TEST_DATA);
   let shouldGutterShow = options.min === false && options.max === false;
 
   is(graph._gutter.hidden, shouldGutterShow,
@@ -49,5 +49,5 @@ async function testGraph(parent, options) {
   is(graph._avgGutterLine.hidden, options.avg === false,
     `The avg gutter should ${options.avg === false ? "not " : ""}be shown`);
 
-  await graph.destroy();
+  yield graph.destroy();
 }
diff --git a/devtools/client/shared/test/browser_graphs-10a.js b/devtools/client/shared/test/browser_graphs-10a.js
index 68977970da2c..7f66156f455e 100644
--- a/devtools/client/shared/test/browser_graphs-10a.js
+++ b/devtools/client/shared/test/browser_graphs-10a.js
@@ -29,37 +29,37 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost("window");
+function* performTest() {
+  let [host,, doc] = yield createHost("window");
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   let refreshCount = 0;
   graph.on("refresh", () => refreshCount++);
 
-  await testGraph(host, graph);
+  yield testGraph(host, graph);
 
   is(refreshCount, 2, "The graph should've been refreshed 2 times.");
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(host, graph) {
+function* testGraph(host, graph) {
   graph.setData(TEST_DATA);
   let initialBounds = host.frame.getBoundingClientRect();
 
   host._window.resizeBy(-100, -100);
-  await graph.once("refresh");
+  yield graph.once("refresh");
   let newBounds = host.frame.getBoundingClientRect();
 
   is(initialBounds.width - newBounds.width, 100,
@@ -99,7 +99,7 @@ async function testGraph(host, graph) {
     "The current selection end value is correct (3).");
 
   host._window.resizeBy(100, 100);
-  await graph.once("refresh");
+  yield graph.once("refresh");
   let newerBounds = host.frame.getBoundingClientRect();
 
   is(initialBounds.width - newerBounds.width, 0,
diff --git a/devtools/client/shared/test/browser_graphs-10b.js b/devtools/client/shared/test/browser_graphs-10b.js
index 4b9428c2b1ec..a29bdfd253da 100644
--- a/devtools/client/shared/test/browser_graphs-10b.js
+++ b/devtools/client/shared/test/browser_graphs-10b.js
@@ -30,42 +30,42 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost("window");
+function* performTest() {
+  let [host,, doc] = yield createHost("window");
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
   let graph = new LineGraphWidget(doc.body, "fps");
   graph.fixedWidth = 200;
   graph.fixedHeight = 100;
-  await graph.once("ready");
+  yield graph.once("ready");
 
   let refreshCount = 0;
   let refreshCancelledCount = 0;
   graph.on("refresh", () => refreshCount++);
   graph.on("refresh-cancelled", () => refreshCancelledCount++);
 
-  await testGraph(host, graph);
+  yield testGraph(host, graph);
 
   is(refreshCount, 0, "The graph shouldn't have been refreshed at all.");
   is(refreshCancelledCount, 2, "The graph should've had 2 refresh attempts.");
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(host, graph) {
+function* testGraph(host, graph) {
   graph.setData(TEST_DATA);
 
   host._window.resizeBy(-100, -100);
-  await graph.once("refresh-cancelled");
+  yield graph.once("refresh-cancelled");
 
   host._window.resizeBy(100, 100);
-  await graph.once("refresh-cancelled");
+  yield graph.once("refresh-cancelled");
 }
diff --git a/devtools/client/shared/test/browser_graphs-10c.js b/devtools/client/shared/test/browser_graphs-10c.js
index f0188054e068..f68a3e804e5c 100644
--- a/devtools/client/shared/test/browser_graphs-10c.js
+++ b/devtools/client/shared/test/browser_graphs-10c.js
@@ -27,36 +27,36 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost("window");
+function* performTest() {
+  let [host,, doc] = yield createHost("window");
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
   let graph = new LineGraphWidget(doc.body, "fps");
-  await graph.once("ready");
+  yield graph.once("ready");
 
   let refreshCount = 0;
   graph.on("refresh", () => refreshCount++);
 
-  await testGraph(host, graph);
+  yield testGraph(host, graph);
 
   is(refreshCount, 2, "The graph should've been refreshed 2 times.");
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(host, graph) {
+function* testGraph(host, graph) {
   graph.setData(TEST_DATA);
 
   host._window.resizeTo(500, 500);
-  await graph.once("refresh");
+  yield graph.once("refresh");
   let oldBounds = host.frame.getBoundingClientRect();
 
   is(graph._width, oldBounds.width * window.devicePixelRatio,
@@ -75,7 +75,7 @@ async function testGraph(host, graph) {
   info("Making sure the selection updates when the window is resized");
 
   host._window.resizeTo(250, 250);
-  await graph.once("refresh");
+  yield graph.once("refresh");
   let newBounds = host.frame.getBoundingClientRect();
 
   is(graph._width, newBounds.width * window.devicePixelRatio,
diff --git a/devtools/client/shared/test/browser_graphs-11a.js b/devtools/client/shared/test/browser_graphs-11a.js
index 21309fe95629..27e5b292ce14 100644
--- a/devtools/client/shared/test/browser_graphs-11a.js
+++ b/devtools/client/shared/test/browser_graphs-11a.js
@@ -13,20 +13,20 @@ const CATEGORIES = [
   { color: "#70bf53", label: "Baz" }
 ];
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new BarGraphWidget(doc.body);
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-11b.js b/devtools/client/shared/test/browser_graphs-11b.js
index bc964b327edd..4df1c4495fa1 100644
--- a/devtools/client/shared/test/browser_graphs-11b.js
+++ b/devtools/client/shared/test/browser_graphs-11b.js
@@ -13,14 +13,14 @@ const CATEGORIES = [
   { color: "#70bf53", label: "Baz" }
 ];
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -28,14 +28,14 @@ async function performTest() {
   graph.fixedWidth = 200;
   graph.fixedHeight = 100;
 
-  await graph.once("ready");
-  await testGraph(graph);
+  yield graph.once("ready");
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
+function* testGraph(graph) {
   graph.format = CATEGORIES;
   graph.dataOffsetX = 1000;
   graph.setData([{
@@ -60,19 +60,19 @@ async function testGraph(graph) {
   is(legendItems.length, 3,
     "Three legend items should exist in the entire graph.");
 
-  await testLegend(graph, 0, {
+  yield testLegend(graph, 0, {
     highlights: "[{type:0, start:34.33333333333333, end:66.66666666666666, top:85, bottom:100}, {type:0, start:67.66666666666666, end:100, top:70, bottom:100}, {type:0, start:134.33333333333331, end:166.66666666666666, top:55, bottom:100}, {type:0, start:167.66666666666666, end:200, top:55, bottom:100}]",
     selection: "({start:34.33333333333333, end:200})",
     leftmost: "({type:0, start:34.33333333333333, end:66.66666666666666, top:85, bottom:100})",
     rightmost: "({type:0, start:167.66666666666666, end:200, top:55, bottom:100})"
   });
-  await testLegend(graph, 1, {
+  yield testLegend(graph, 1, {
     highlights: "[{type:1, start:0, end:33.33333333333333, top:70, bottom:100}, {type:1, start:67.66666666666666, end:100, top:54, bottom:69}, {type:1, start:101, end:133.33333333333331, top:55, bottom:100}, {type:1, start:167.66666666666666, end:200, top:24, bottom:54}]",
     selection: "({start:0, end:200})",
     leftmost: "({type:1, start:0, end:33.33333333333333, top:70, bottom:100})",
     rightmost: "({type:1, start:167.66666666666666, end:200, top:24, bottom:54})"
   });
-  await testLegend(graph, 2, {
+  yield testLegend(graph, 2, {
     highlights: "[{type:2, start:0, end:33.33333333333333, top:24, bottom:69}, {type:2, start:34.33333333333333, end:66.66666666666666, top:54, bottom:84}, {type:2, start:101, end:133.33333333333331, top:39, bottom:54}, {type:2, start:134.33333333333331, end:166.66666666666666, top:24, bottom:54}]",
     selection: "({start:0, end:166.66666666666666})",
     leftmost: "({type:2, start:0, end:33.33333333333333, top:24, bottom:69})",
@@ -81,7 +81,7 @@ async function testGraph(graph) {
   /* eslint-enable max-len */
 }
 
-async function testLegend(graph, index, { highlights, selection, leftmost, rightmost }) {
+function* testLegend(graph, index, { highlights, selection, leftmost, rightmost }) {
   // Hover.
 
   let legendItems = graph._document.querySelectorAll(".bar-graph-widget-legend-item");
@@ -91,7 +91,7 @@ async function testLegend(graph, index, { highlights, selection, leftmost, right
   graph._onLegendMouseOver({ target: colorBlock });
   ok(!graph.hasMask(), "The graph shouldn't get highlights immediately.");
 
-  let [type, rects] = await debounced;
+  let [type, rects] = yield debounced;
   ok(graph.hasMask(), "The graph should now have highlights.");
 
   is(type, index,
@@ -105,7 +105,7 @@ async function testLegend(graph, index, { highlights, selection, leftmost, right
   graph._onLegendMouseOut();
   ok(!graph.hasMask(), "The graph shouldn't have highlights anymore.");
 
-  await unhovered;
+  yield unhovered;
   ok(true, "The 'legend-mouseout' event was emitted.");
 
   // Select.
@@ -115,7 +115,7 @@ async function testLegend(graph, index, { highlights, selection, leftmost, right
   ok(graph.hasSelection(), "The graph should now have a selection.");
   is(graph.getSelection().toSource(), selection, "The graph has a correct selection.");
 
-  let [left, right] = await selected;
+  let [left, right] = yield selected;
   is(left.toSource(), leftmost, "The correct leftmost data block was found.");
   is(right.toSource(), rightmost, "The correct rightmost data block was found.");
 
diff --git a/devtools/client/shared/test/browser_graphs-12.js b/devtools/client/shared/test/browser_graphs-12.js
index 80c7456d5b8c..1836d016c083 100644
--- a/devtools/client/shared/test/browser_graphs-12.js
+++ b/devtools/client/shared/test/browser_graphs-12.js
@@ -9,14 +9,14 @@ const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget"
 const BarGraphWidget = require("devtools/client/shared/widgets/BarGraphWidget");
 const {CanvasGraphUtils} = require("devtools/client/shared/widgets/Graphs");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -34,13 +34,13 @@ async function performTest() {
   CanvasGraphUtils.linkAnimation(graph1, graph2);
   CanvasGraphUtils.linkSelection(graph1, graph2);
 
-  await graph1.ready();
-  await graph2.ready();
+  yield graph1.ready();
+  yield graph2.ready();
 
   testGraphs(graph1, graph2);
 
-  await graph1.destroy();
-  await graph2.destroy();
+  yield graph1.destroy();
+  yield graph2.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-13.js b/devtools/client/shared/test/browser_graphs-13.js
index cd02e2620bbe..d671291edd8d 100644
--- a/devtools/client/shared/test/browser_graphs-13.js
+++ b/devtools/client/shared/test/browser_graphs-13.js
@@ -7,14 +7,14 @@
 
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   doc.body.setAttribute("style",
                         "position: fixed; width: 100%; height: 100%; margin: 0;");
 
@@ -22,10 +22,10 @@ async function performTest() {
   graph.fixedWidth = 200;
   graph.fixedHeight = 100;
 
-  await graph.ready();
+  yield graph.ready();
   testGraph(host, graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_graphs-14.js b/devtools/client/shared/test/browser_graphs-14.js
index 71b5419ee413..4001f8e6d22c 100644
--- a/devtools/client/shared/test/browser_graphs-14.js
+++ b/devtools/client/shared/test/browser_graphs-14.js
@@ -29,23 +29,23 @@ const TEST_DATA = [
 ];
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
+function* testGraph(graph) {
   let mouseDownEvents = 0;
   let mouseUpEvents = 0;
   let scrollEvents = 0;
@@ -53,7 +53,7 @@ async function testGraph(graph) {
   graph.on("mouseup", () => mouseUpEvents++);
   graph.on("scroll", () => scrollEvents++);
 
-  await graph.setDataWhenReady(TEST_DATA);
+  yield graph.setDataWhenReady(TEST_DATA);
 
   info("Making a selection.");
 
diff --git a/devtools/client/shared/test/browser_graphs-15.js b/devtools/client/shared/test/browser_graphs-15.js
index 021fba8ce094..af2c9875eeb9 100644
--- a/devtools/client/shared/test/browser_graphs-15.js
+++ b/devtools/client/shared/test/browser_graphs-15.js
@@ -25,25 +25,25 @@ for (let frameRate of FRAMES) {
 
 const LineGraphWidget = require("devtools/client/shared/widgets/LineGraphWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new LineGraphWidget(doc.body, "fps");
 
-  await testGraph(graph);
+  yield testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
-async function testGraph(graph) {
+function* testGraph(graph) {
   console.log("test data", TEST_DATA);
-  await graph.setDataFromTimestamps(TEST_DATA, INTERVAL, DURATION);
+  yield graph.setDataFromTimestamps(TEST_DATA, INTERVAL, DURATION);
   is(graph._avgTooltip.querySelector("[text=value]").textContent, "50",
     "The average tooltip displays the correct value.");
 }
diff --git a/devtools/client/shared/test/browser_graphs-16.js b/devtools/client/shared/test/browser_graphs-16.js
index 7e2479b2e4cf..194cb751c9d9 100644
--- a/devtools/client/shared/test/browser_graphs-16.js
+++ b/devtools/client/shared/test/browser_graphs-16.js
@@ -21,20 +21,20 @@ const SECTIONS = [
   { color: "blue" }
 ];
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host,, doc] = await createHost();
+function* performTest() {
+  let [host,, doc] = yield createHost();
   let graph = new MountainGraphWidget(doc.body);
-  await graph.once("ready");
+  yield graph.once("ready");
 
   testGraph(graph);
 
-  await graph.destroy();
+  yield graph.destroy();
   host.destroy();
 }
 
diff --git a/devtools/client/shared/test/browser_html_tooltip-01.js b/devtools/client/shared/test/browser_html_tooltip-01.js
index a6e425e7a46e..8d3c67e753ee 100644
--- a/devtools/client/shared/test/browser_html_tooltip-01.js
+++ b/devtools/client/shared/test/browser_html_tooltip-01.js
@@ -24,20 +24,20 @@ function getTooltipContent(doc) {
   return div;
 }
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Run tests for a Tooltip without using a XUL panel");
   useXulWrapper = false;
-  await runTests(doc);
+  yield runTests(doc);
 
   info("Run tests for a Tooltip with a XUL panel");
   useXulWrapper = true;
-  await runTests(doc);
+  yield runTests(doc);
 });
 
-async function runTests(doc) {
-  await addTab("about:blank");
+function* runTests(doc) {
+  yield addTab("about:blank");
   let tooltip = new HTMLTooltip(doc, {useXulWrapper});
 
   info("Set tooltip content");
@@ -53,10 +53,10 @@ async function runTests(doc) {
   let onShown = tooltip.once("shown");
   tooltip.show(doc.getElementById("box1"));
 
-  await onShown;
+  yield onShown;
   is(shown, 1, "Event shown was fired once");
 
-  await waitForReflow(tooltip);
+  yield waitForReflow(tooltip);
   is(tooltip.isVisible(), true, "Tooltip is visible");
 
   info("Hide the tooltip and check the expected events are fired.");
@@ -67,10 +67,10 @@ async function runTests(doc) {
   let onPopupHidden = tooltip.once("hidden");
   tooltip.hide();
 
-  await onPopupHidden;
+  yield onPopupHidden;
   is(hidden, 1, "Event hidden was fired once");
 
-  await waitForReflow(tooltip);
+  yield waitForReflow(tooltip);
   is(tooltip.isVisible(), false, "Tooltip is not visible");
 
   tooltip.destroy();
diff --git a/devtools/client/shared/test/browser_html_tooltip-02.js b/devtools/client/shared/test/browser_html_tooltip-02.js
index 46c5c5d83891..b4e2bb8a7f51 100644
--- a/devtools/client/shared/test/browser_html_tooltip-02.js
+++ b/devtools/client/shared/test/browser_html_tooltip-02.js
@@ -15,63 +15,63 @@ loadHelperScript("helper_html_tooltip.js");
 
 let useXulWrapper;
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("about:blank");
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Run tests for a Tooltip without using a XUL panel");
   useXulWrapper = false;
-  await runTests(doc);
+  yield runTests(doc);
 
   info("Run tests for a Tooltip with a XUL panel");
   useXulWrapper = true;
-  await runTests(doc);
+  yield runTests(doc);
 });
 
-async function runTests(doc) {
-  await testClickInTooltipContent(doc);
-  await testConsumeOutsideClicksFalse(doc);
-  await testConsumeOutsideClicksTrue(doc);
-  await testConsumeWithRightClick(doc);
-  await testClickInOuterIframe(doc);
-  await testClickInInnerIframe(doc);
+function* runTests(doc) {
+  yield testClickInTooltipContent(doc);
+  yield testConsumeOutsideClicksFalse(doc);
+  yield testConsumeOutsideClicksTrue(doc);
+  yield testConsumeWithRightClick(doc);
+  yield testClickInOuterIframe(doc);
+  yield testClickInInnerIframe(doc);
 }
 
-async function testClickInTooltipContent(doc) {
+function* testClickInTooltipContent(doc) {
   info("Test a tooltip is not closed when clicking inside itself");
 
   let tooltip = new HTMLTooltip(doc, {useXulWrapper});
   tooltip.setContent(getTooltipContent(doc), {width: 100, height: 50});
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let onTooltipContainerClick = once(tooltip.container, "click");
   EventUtils.synthesizeMouseAtCenter(tooltip.container, {}, doc.defaultView);
-  await onTooltipContainerClick;
+  yield onTooltipContainerClick;
   is(tooltip.isVisible(), true, "Tooltip is still visible");
 
   tooltip.destroy();
 }
 
-async function testConsumeOutsideClicksFalse(doc) {
+function* testConsumeOutsideClicksFalse(doc) {
   info("Test closing a tooltip via click with consumeOutsideClicks: false");
   let box4 = doc.getElementById("box4");
 
   let tooltip = new HTMLTooltip(doc, {consumeOutsideClicks: false, useXulWrapper});
   tooltip.setContent(getTooltipContent(doc), {width: 100, height: 50});
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let onBox4Clicked = once(box4, "click");
   let onHidden = once(tooltip, "hidden");
   EventUtils.synthesizeMouseAtCenter(box4, {}, doc.defaultView);
-  await onHidden;
-  await onBox4Clicked;
+  yield onHidden;
+  yield onBox4Clicked;
 
   is(tooltip.isVisible(), false, "Tooltip is hidden");
 
   tooltip.destroy();
 }
 
-async function testConsumeOutsideClicksTrue(doc) {
+function* testConsumeOutsideClicksTrue(doc) {
   info("Test closing a tooltip via click with consumeOutsideClicks: true");
   let box4 = doc.getElementById("box4");
 
@@ -81,11 +81,11 @@ async function testConsumeOutsideClicksTrue(doc) {
 
   let tooltip = new HTMLTooltip(doc, {consumeOutsideClicks: true, useXulWrapper});
   tooltip.setContent(getTooltipContent(doc), {width: 100, height: 50});
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let onHidden = once(tooltip, "hidden");
   EventUtils.synthesizeMouseAtCenter(box4, {}, doc.defaultView);
-  await onHidden;
+  yield onHidden;
 
   is(box4clicks, 0, "box4 catched no click event");
   is(tooltip.isVisible(), false, "Tooltip is hidden");
@@ -93,13 +93,13 @@ async function testConsumeOutsideClicksTrue(doc) {
   tooltip.destroy();
 }
 
-async function testConsumeWithRightClick(doc) {
+function* testConsumeWithRightClick(doc) {
   info("Test closing a tooltip with a right-click, with consumeOutsideClicks: true");
   let box4 = doc.getElementById("box4");
 
   let tooltip = new HTMLTooltip(doc, {consumeOutsideClicks: true, useXulWrapper});
   tooltip.setContent(getTooltipContent(doc), {width: 100, height: 50});
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   // Only left-click events should be consumed, so we expect to catch a click when using
   // {button: 2}, which simulates a right-click.
@@ -107,31 +107,31 @@ async function testConsumeWithRightClick(doc) {
   let onBox4Clicked = once(box4, "click");
   let onHidden = once(tooltip, "hidden");
   EventUtils.synthesizeMouseAtCenter(box4, {button: 2}, doc.defaultView);
-  await onHidden;
-  await onBox4Clicked;
+  yield onHidden;
+  yield onBox4Clicked;
 
   is(tooltip.isVisible(), false, "Tooltip is hidden");
 
   tooltip.destroy();
 }
 
-async function testClickInOuterIframe(doc) {
+function* testClickInOuterIframe(doc) {
   info("Test clicking an iframe outside of the tooltip closes the tooltip");
   let frame = doc.getElementById("frame");
 
   let tooltip = new HTMLTooltip(doc, {useXulWrapper});
   tooltip.setContent(getTooltipContent(doc), {width: 100, height: 50});
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let onHidden = once(tooltip, "hidden");
   EventUtils.synthesizeMouseAtCenter(frame, {}, doc.defaultView);
-  await onHidden;
+  yield onHidden;
 
   is(tooltip.isVisible(), false, "Tooltip is hidden");
   tooltip.destroy();
 }
 
-async function testClickInInnerIframe(doc) {
+function* testClickInInnerIframe(doc) {
   info("Test clicking an iframe inside the tooltip content does not close the tooltip");
 
   let tooltip = new HTMLTooltip(doc, {consumeOutsideClicks: false, useXulWrapper});
@@ -140,11 +140,11 @@ async function testClickInInnerIframe(doc) {
   iframe.style.width = "100px";
   iframe.style.height = "50px";
   tooltip.setContent(iframe, {width: 100, height: 50});
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let onTooltipContainerClick = once(tooltip.container, "click");
   EventUtils.synthesizeMouseAtCenter(tooltip.container, {}, doc.defaultView);
-  await onTooltipContainerClick;
+  yield onTooltipContainerClick;
 
   is(tooltip.isVisible(), true, "Tooltip is still visible");
 
diff --git a/devtools/client/shared/test/browser_html_tooltip-03.js b/devtools/client/shared/test/browser_html_tooltip-03.js
index 29c4a7cd98ea..1d5e07b57800 100644
--- a/devtools/client/shared/test/browser_html_tooltip-03.js
+++ b/devtools/client/shared/test/browser_html_tooltip-03.js
@@ -16,81 +16,81 @@ loadHelperScript("helper_html_tooltip.js");
 
 let useXulWrapper;
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [, , doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("about:blank");
+  let [, , doc] = yield createHost("bottom", TEST_URI);
 
   info("Run tests for a Tooltip without using a XUL panel");
   useXulWrapper = false;
-  await runTests(doc);
+  yield runTests(doc);
 
   info("Run tests for a Tooltip with a XUL panel");
   useXulWrapper = true;
-  await runTests(doc);
+  yield runTests(doc);
 });
 
-async function runTests(doc) {
-  await testNoAutoFocus(doc);
-  await testAutoFocus(doc);
-  await testAutoFocusPreservesFocusChange(doc);
+function* runTests(doc) {
+  yield testNoAutoFocus(doc);
+  yield testAutoFocus(doc);
+  yield testAutoFocusPreservesFocusChange(doc);
 }
 
-async function testNoAutoFocus(doc) {
-  await focusNode(doc, "#box4-input");
+function* testNoAutoFocus(doc) {
+  yield focusNode(doc, "#box4-input");
   ok(doc.activeElement.closest("#box4-input"), "Focus is in the #box4-input");
 
   info("Test a tooltip without autofocus will not take focus");
-  let tooltip = await createTooltip(doc, false);
+  let tooltip = yield createTooltip(doc, false);
 
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
   ok(doc.activeElement.closest("#box4-input"), "Focus is still in the #box4-input");
 
-  await hideTooltip(tooltip);
-  await blurNode(doc, "#box4-input");
+  yield hideTooltip(tooltip);
+  yield blurNode(doc, "#box4-input");
 
   tooltip.destroy();
 }
 
-async function testAutoFocus(doc) {
-  await focusNode(doc, "#box4-input");
+function* testAutoFocus(doc) {
+  yield focusNode(doc, "#box4-input");
   ok(doc.activeElement.closest("#box4-input"), "Focus is in the #box4-input");
 
   info("Test autofocus tooltip takes focus when displayed, " +
     "and restores the focus when hidden");
-  let tooltip = await createTooltip(doc, true);
+  let tooltip = yield createTooltip(doc, true);
 
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
   ok(doc.activeElement.closest(".tooltip-content"), "Focus is in the tooltip");
 
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
   ok(doc.activeElement.closest("#box4-input"), "Focus is in the #box4-input");
 
   info("Blur the textbox before moving to the next test to reset the state.");
-  await blurNode(doc, "#box4-input");
+  yield blurNode(doc, "#box4-input");
 
   tooltip.destroy();
 }
 
-async function testAutoFocusPreservesFocusChange(doc) {
-  await focusNode(doc, "#box4-input");
+function* testAutoFocusPreservesFocusChange(doc) {
+  yield focusNode(doc, "#box4-input");
   ok(doc.activeElement.closest("#box4-input"), "Focus is still in the #box3-input");
 
   info("Test autofocus tooltip takes focus when displayed, " +
     "but does not try to restore the active element if it is not focused when hidden");
-  let tooltip = await createTooltip(doc, true);
+  let tooltip = yield createTooltip(doc, true);
 
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
   ok(doc.activeElement.closest(".tooltip-content"), "Focus is in the tooltip");
 
   info("Move the focus to #box3-input while the tooltip is displayed");
-  await focusNode(doc, "#box3-input");
+  yield focusNode(doc, "#box3-input");
   ok(doc.activeElement.closest("#box3-input"), "Focus moved to the #box3-input");
 
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
   ok(doc.activeElement.closest("#box3-input"), "Focus is still in the #box3-input");
 
   info("Blur the textbox before moving to the next test to reset the state.");
-  await blurNode(doc, "#box3-input");
+  yield blurNode(doc, "#box3-input");
 
   tooltip.destroy();
 }
@@ -126,7 +126,7 @@ function blurNode(doc, selector) {
  * @return {Promise} promise that will resolve the HTMLTooltip instance created when the
  *         tooltip content will be ready.
  */
-function createTooltip(doc, autofocus) {
+function* createTooltip(doc, autofocus) {
   let tooltip = new HTMLTooltip(doc, {autofocus, useXulWrapper});
   let div = doc.createElementNS(HTML_NS, "div");
   div.classList.add("tooltip-content");
diff --git a/devtools/client/shared/test/browser_html_tooltip-04.js b/devtools/client/shared/test/browser_html_tooltip-04.js
index 671e1b764624..a04f0d502b13 100644
--- a/devtools/client/shared/test/browser_html_tooltip-04.js
+++ b/devtools/client/shared/test/browser_html_tooltip-04.js
@@ -18,12 +18,12 @@ loadHelperScript("helper_html_tooltip.js");
 const TOOLTIP_HEIGHT = 30;
 const TOOLTIP_WIDTH = 100;
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 400px high;
-  await pushPref("devtools.toolbox.footer.height", 400);
+  yield pushPref("devtools.toolbox.footer.height", 400);
 
-  await addTab("about:blank");
-  let [,, doc] = await createHost("bottom", TEST_URI);
+  yield addTab("about:blank");
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Create HTML tooltip");
   let tooltip = new HTMLTooltip(doc, {useXulWrapper: false});
@@ -39,56 +39,56 @@ add_task(async function () {
 
   // box1: Can only fit below box1
   info("Display the tooltip on box1.");
-  await showTooltip(tooltip, box1);
+  yield showTooltip(tooltip, box1);
   let expectedTooltipGeometry = {position: "bottom", height, width};
   checkTooltipGeometry(tooltip, box1, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on top of box1.");
-  await showTooltip(tooltip, box1, {position: "top"});
+  yield showTooltip(tooltip, box1, {position: "top"});
   expectedTooltipGeometry = {position: "bottom", height, width};
   checkTooltipGeometry(tooltip, box1, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // box2: Can fit above or below, will default to bottom, more height
   // available.
   info("Try to display the tooltip on box2.");
-  await showTooltip(tooltip, box2);
+  yield showTooltip(tooltip, box2);
   expectedTooltipGeometry = {position: "bottom", height, width};
   checkTooltipGeometry(tooltip, box2, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on top of box2.");
-  await showTooltip(tooltip, box2, {position: "top"});
+  yield showTooltip(tooltip, box2, {position: "top"});
   expectedTooltipGeometry = {position: "top", height, width};
   checkTooltipGeometry(tooltip, box2, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // box3: Can fit above or below, will default to top, more height available.
   info("Try to display the tooltip on box3.");
-  await showTooltip(tooltip, box3);
+  yield showTooltip(tooltip, box3);
   expectedTooltipGeometry = {position: "top", height, width};
   checkTooltipGeometry(tooltip, box3, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on bottom of box3.");
-  await showTooltip(tooltip, box3, {position: "bottom"});
+  yield showTooltip(tooltip, box3, {position: "bottom"});
   expectedTooltipGeometry = {position: "bottom", height, width};
   checkTooltipGeometry(tooltip, box3, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // box4: Can only fit above box4
   info("Display the tooltip on box4.");
-  await showTooltip(tooltip, box4);
+  yield showTooltip(tooltip, box4);
   expectedTooltipGeometry = {position: "top", height, width};
   checkTooltipGeometry(tooltip, box4, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on bottom of box4.");
-  await showTooltip(tooltip, box4, {position: "bottom"});
+  yield showTooltip(tooltip, box4, {position: "bottom"});
   expectedTooltipGeometry = {position: "top", height, width};
   checkTooltipGeometry(tooltip, box4, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   is(tooltip.isVisible(), false, "Tooltip is not visible");
 
diff --git a/devtools/client/shared/test/browser_html_tooltip-05.js b/devtools/client/shared/test/browser_html_tooltip-05.js
index 00d0f4ecbe36..bd5891d5b78b 100644
--- a/devtools/client/shared/test/browser_html_tooltip-05.js
+++ b/devtools/client/shared/test/browser_html_tooltip-05.js
@@ -18,11 +18,11 @@ loadHelperScript("helper_html_tooltip.js");
 const TOOLTIP_HEIGHT = 200;
 const TOOLTIP_WIDTH = 200;
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 200px high;
-  await pushPref("devtools.toolbox.footer.height", 200);
-  await addTab("about:blank");
-  let [,, doc] = await createHost("bottom", TEST_URI);
+  yield pushPref("devtools.toolbox.footer.height", 200);
+  yield addTab("about:blank");
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Create HTML tooltip");
   let tooltip = new HTMLTooltip(doc, {useXulWrapper: false});
@@ -39,58 +39,58 @@ add_task(async function () {
   // box1: Can not fit above or below box1, default to bottom with a reduced
   // height of 150px.
   info("Display the tooltip on box1.");
-  await showTooltip(tooltip, box1);
+  yield showTooltip(tooltip, box1);
   let expectedTooltipGeometry = {position: "bottom", height: 150, width};
   checkTooltipGeometry(tooltip, box1, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on top of box1.");
-  await showTooltip(tooltip, box1, {position: "top"});
+  yield showTooltip(tooltip, box1, {position: "top"});
   expectedTooltipGeometry = {position: "bottom", height: 150, width};
   checkTooltipGeometry(tooltip, box1, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // box2: Can not fit above or below box2, default to bottom with a reduced
   // height of 100px.
   info("Try to display the tooltip on box2.");
-  await showTooltip(tooltip, box2);
+  yield showTooltip(tooltip, box2);
   expectedTooltipGeometry = {position: "bottom", height: 100, width};
   checkTooltipGeometry(tooltip, box2, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on top of box2.");
-  await showTooltip(tooltip, box2, {position: "top"});
+  yield showTooltip(tooltip, box2, {position: "top"});
   expectedTooltipGeometry = {position: "bottom", height: 100, width};
   checkTooltipGeometry(tooltip, box2, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // box3: Can not fit above or below box3, default to top with a reduced height
   // of 100px.
   info("Try to display the tooltip on box3.");
-  await showTooltip(tooltip, box3);
+  yield showTooltip(tooltip, box3);
   expectedTooltipGeometry = {position: "top", height: 100, width};
   checkTooltipGeometry(tooltip, box3, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on bottom of box3.");
-  await showTooltip(tooltip, box3, {position: "bottom"});
+  yield showTooltip(tooltip, box3, {position: "bottom"});
   expectedTooltipGeometry = {position: "top", height: 100, width};
   checkTooltipGeometry(tooltip, box3, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // box4: Can not fit above or below box4, default to top with a reduced height
   // of 150px.
   info("Display the tooltip on box4.");
-  await showTooltip(tooltip, box4);
+  yield showTooltip(tooltip, box4);
   expectedTooltipGeometry = {position: "top", height: 150, width};
   checkTooltipGeometry(tooltip, box4, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   info("Try to display the tooltip on bottom of box4.");
-  await showTooltip(tooltip, box4, {position: "bottom"});
+  yield showTooltip(tooltip, box4, {position: "bottom"});
   expectedTooltipGeometry = {position: "top", height: 150, width};
   checkTooltipGeometry(tooltip, box4, expectedTooltipGeometry);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   is(tooltip.isVisible(), false, "Tooltip is not visible");
 
diff --git a/devtools/client/shared/test/browser_html_tooltip_arrow-01.js b/devtools/client/shared/test/browser_html_tooltip_arrow-01.js
index 38fd5cf56af6..9806e2be500f 100644
--- a/devtools/client/shared/test/browser_html_tooltip_arrow-01.js
+++ b/devtools/client/shared/test/browser_html_tooltip_arrow-01.js
@@ -17,23 +17,23 @@ loadHelperScript("helper_html_tooltip.js");
 
 let useXulWrapper;
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 200px high;
-  await pushPref("devtools.toolbox.footer.height", 200);
+  yield pushPref("devtools.toolbox.footer.height", 200);
 
-  await addTab("about:blank");
-  let [,, doc] = await createHost("bottom", TEST_URI);
+  yield addTab("about:blank");
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Run tests for a Tooltip without using a XUL panel");
   useXulWrapper = false;
-  await runTests(doc);
+  yield runTests(doc);
 
   info("Run tests for a Tooltip with a XUL panel");
   useXulWrapper = true;
-  await runTests(doc);
+  yield runTests(doc);
 });
 
-async function runTests(doc) {
+function* runTests(doc) {
   info("Create HTML tooltip");
   let tooltip = new HTMLTooltip(doc, {type: "arrow", useXulWrapper});
   let div = doc.createElementNS(HTML_NS, "div");
@@ -45,7 +45,7 @@ async function runTests(doc) {
   let elements = [...doc.querySelectorAll(".anchor")];
   for (let el of elements) {
     info("Display the tooltip on an anchor.");
-    await showTooltip(tooltip, el);
+    yield showTooltip(tooltip, el);
 
     let arrow = tooltip.arrow;
     ok(arrow, "Tooltip has an arrow");
@@ -67,7 +67,7 @@ async function runTests(doc) {
     ok(isInPanel,
       "The tooltip arrow remains inside the tooltip panel horizontally");
 
-    await hideTooltip(tooltip);
+    yield hideTooltip(tooltip);
   }
 
   tooltip.destroy();
diff --git a/devtools/client/shared/test/browser_html_tooltip_arrow-02.js b/devtools/client/shared/test/browser_html_tooltip_arrow-02.js
index d3261543e353..034d2fbd8cef 100644
--- a/devtools/client/shared/test/browser_html_tooltip_arrow-02.js
+++ b/devtools/client/shared/test/browser_html_tooltip_arrow-02.js
@@ -17,22 +17,22 @@ loadHelperScript("helper_html_tooltip.js");
 
 let useXulWrapper;
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 200px high;
-  await pushPref("devtools.toolbox.footer.height", 200);
+  yield pushPref("devtools.toolbox.footer.height", 200);
 
-  let [,, doc] = await createHost("bottom", TEST_URI);
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Run tests for a Tooltip without using a XUL panel");
   useXulWrapper = false;
-  await runTests(doc);
+  yield runTests(doc);
 
   info("Run tests for a Tooltip with a XUL panel");
   useXulWrapper = true;
-  await runTests(doc);
+  yield runTests(doc);
 });
 
-async function runTests(doc) {
+function* runTests(doc) {
   info("Create HTML tooltip");
   let tooltip = new HTMLTooltip(doc, {type: "arrow", useXulWrapper});
   let div = doc.createElementNS(HTML_NS, "div");
@@ -44,7 +44,7 @@ async function runTests(doc) {
   let elements = [...doc.querySelectorAll(".anchor")];
   for (let el of elements) {
     info("Display the tooltip on an anchor.");
-    await showTooltip(tooltip, el);
+    yield showTooltip(tooltip, el);
 
     let arrow = tooltip.arrow;
     ok(arrow, "Tooltip has an arrow");
@@ -65,7 +65,7 @@ async function runTests(doc) {
                     arrowBounds.right <= panelBounds.right;
     ok(isInPanel,
       "The tooltip arrow remains inside the tooltip panel horizontally");
-    await hideTooltip(tooltip);
+    yield hideTooltip(tooltip);
   }
 
   tooltip.destroy();
diff --git a/devtools/client/shared/test/browser_html_tooltip_consecutive-show.js b/devtools/client/shared/test/browser_html_tooltip_consecutive-show.js
index 86150df1b269..ea66876117c3 100644
--- a/devtools/client/shared/test/browser_html_tooltip_consecutive-show.js
+++ b/devtools/client/shared/test/browser_html_tooltip_consecutive-show.js
@@ -22,8 +22,8 @@ function getTooltipContent(doc) {
   return div;
 }
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   let box1 = doc.getElementById("box1");
   let box2 = doc.getElementById("box2");
@@ -54,7 +54,7 @@ add_task(async function () {
   checkTooltipGeometry(tooltip, box4, {position: "top", width, height});
 
   info("Hide tooltip before leaving test");
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   tooltip.destroy();
 });
diff --git a/devtools/client/shared/test/browser_html_tooltip_hover.js b/devtools/client/shared/test/browser_html_tooltip_hover.js
index 67ec961bbefe..e762cba079c3 100644
--- a/devtools/client/shared/test/browser_html_tooltip_hover.js
+++ b/devtools/client/shared/test/browser_html_tooltip_hover.js
@@ -14,10 +14,10 @@ const TEST_URI = CHROME_URL_ROOT + "doc_html_tooltip_hover.xul";
 const {HTMLTooltip} = require("devtools/client/shared/widgets/tooltip/HTMLTooltip");
 loadHelperScript("helper_html_tooltip.js");
 
-add_task(async function () {
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [,, doc] = yield createHost("bottom", TEST_URI);
   // Wait for full page load before synthesizing events on the page.
-  await waitUntil(() => doc.readyState === "complete");
+  yield waitUntil(() => doc.readyState === "complete");
 
   let width = 100, height = 50;
   let tooltipContent = doc.createElementNS(HTML_NS, "div");
@@ -29,24 +29,24 @@ add_task(async function () {
   tooltip.startTogglingOnHover(container, () => true);
 
   info("Hover on each of the 4 boxes, expect the tooltip to appear");
-  async function showAndCheck(boxId, position) {
+  function* showAndCheck(boxId, position) {
     info(`Show tooltip on ${boxId}`);
     let box = doc.getElementById(boxId);
     let shown = tooltip.once("shown");
     EventUtils.synthesizeMouseAtCenter(box, { type: "mousemove" }, doc.defaultView);
-    await shown;
+    yield shown;
     checkTooltipGeometry(tooltip, box, {position, width, height});
   }
 
-  await showAndCheck("box1", "bottom");
-  await showAndCheck("box2", "bottom");
-  await showAndCheck("box3", "top");
-  await showAndCheck("box4", "top");
+  yield showAndCheck("box1", "bottom");
+  yield showAndCheck("box2", "bottom");
+  yield showAndCheck("box3", "top");
+  yield showAndCheck("box4", "top");
 
   info("Move out of the container");
   let hidden = tooltip.once("hidden");
   EventUtils.synthesizeMouseAtCenter(container, { type: "mousemove" }, doc.defaultView);
-  await hidden;
+  yield hidden;
 
   info("Destroy the tooltip and finish");
   tooltip.destroy();
diff --git a/devtools/client/shared/test/browser_html_tooltip_offset.js b/devtools/client/shared/test/browser_html_tooltip_offset.js
index da2aa6c6834c..1ca0b1ee47a0 100644
--- a/devtools/client/shared/test/browser_html_tooltip_offset.js
+++ b/devtools/client/shared/test/browser_html_tooltip_offset.js
@@ -13,11 +13,11 @@ const TEST_URI = CHROME_URL_ROOT + "doc_html_tooltip.xul";
 const {HTMLTooltip} = require("devtools/client/shared/widgets/tooltip/HTMLTooltip");
 loadHelperScript("helper_html_tooltip.js");
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 200px high;
-  await pushPref("devtools.toolbox.footer.height", 200);
+  yield pushPref("devtools.toolbox.footer.height", 200);
 
-  let [,, doc] = await createHost("bottom", TEST_URI);
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Test a tooltip is not closed when clicking inside itself");
 
@@ -35,7 +35,7 @@ add_task(async function () {
   tooltip.setContent(div, {width: 50, height: 100});
 
   info("Display the tooltip on box1.");
-  await showTooltip(tooltip, box1, {x: 5, y: 10});
+  yield showTooltip(tooltip, box1, {x: 5, y: 10});
 
   let panelRect = tooltip.container.getBoundingClientRect();
   let anchorRect = box1.getBoundingClientRect();
@@ -46,7 +46,7 @@ add_task(async function () {
   is(panelRect.height, 100, "Tooltip height is at 100px as expected");
 
   info("Display the tooltip on box2.");
-  await showTooltip(tooltip, box2, {x: 5, y: 10});
+  yield showTooltip(tooltip, box2, {x: 5, y: 10});
 
   panelRect = tooltip.container.getBoundingClientRect();
   anchorRect = box2.getBoundingClientRect();
@@ -58,7 +58,7 @@ add_task(async function () {
   is(panelRect.height, 90, "Tooltip height is only 90px");
 
   info("Display the tooltip on box3.");
-  await showTooltip(tooltip, box3, {x: 5, y: 10});
+  yield showTooltip(tooltip, box3, {x: 5, y: 10});
 
   panelRect = tooltip.container.getBoundingClientRect();
   anchorRect = box3.getBoundingClientRect();
@@ -70,7 +70,7 @@ add_task(async function () {
   is(panelRect.height, 90, "Tooltip height is only 90px");
 
   info("Display the tooltip on box4.");
-  await showTooltip(tooltip, box4, {x: 5, y: 10});
+  yield showTooltip(tooltip, box4, {x: 5, y: 10});
 
   panelRect = tooltip.container.getBoundingClientRect();
   anchorRect = box4.getBoundingClientRect();
@@ -80,7 +80,7 @@ add_task(async function () {
   is(panelRect.left, anchorRect.left + 5, "Tooltip left has 5px offset");
   is(panelRect.height, 100, "Tooltip height is at 100px as expected");
 
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   tooltip.destroy();
 });
diff --git a/devtools/client/shared/test/browser_html_tooltip_rtl.js b/devtools/client/shared/test/browser_html_tooltip_rtl.js
index 85aca5c6fc4f..2b9c78b69aed 100644
--- a/devtools/client/shared/test/browser_html_tooltip_rtl.js
+++ b/devtools/client/shared/test/browser_html_tooltip_rtl.js
@@ -19,11 +19,11 @@ const TOOLBOX_WIDTH = 500;
 const TOOLTIP_WIDTH = 150;
 const TOOLTIP_HEIGHT = 30;
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 500px wide (min width is 465px);
-  await pushPref("devtools.toolbox.sidebar.width", TOOLBOX_WIDTH);
+  yield pushPref("devtools.toolbox.sidebar.width", TOOLBOX_WIDTH);
 
-  let [,, doc] = await createHost("side", TEST_URI);
+  let [,, doc] = yield createHost("side", TEST_URI);
 
   info("Test a tooltip is not closed when clicking inside itself");
 
@@ -33,14 +33,14 @@ add_task(async function () {
   div.style.cssText = "box-sizing: border-box; border: 1px solid black";
   tooltip.setContent(div, {width: TOOLTIP_WIDTH, height: TOOLTIP_HEIGHT});
 
-  await testRtlAnchors(doc, tooltip);
-  await testLtrAnchors(doc, tooltip);
-  await hideTooltip(tooltip);
+  yield testRtlAnchors(doc, tooltip);
+  yield testLtrAnchors(doc, tooltip);
+  yield hideTooltip(tooltip);
 
   tooltip.destroy();
 });
 
-async function testRtlAnchors(doc, tooltip) {
+function* testRtlAnchors(doc, tooltip) {
   /*
    * The layout of the test page is as follows:
    *   _______________________________
@@ -60,7 +60,7 @@ async function testRtlAnchors(doc, tooltip) {
   let box2 = doc.getElementById("box2");
 
   info("Display the tooltip on box1.");
-  await showTooltip(tooltip, box1, {position: "bottom"});
+  yield showTooltip(tooltip, box1, {position: "bottom"});
 
   let panelRect = tooltip.container.getBoundingClientRect();
   let anchorRect = box1.getBoundingClientRect();
@@ -72,7 +72,7 @@ async function testRtlAnchors(doc, tooltip) {
   is(panelRect.height, TOOLTIP_HEIGHT, "Tooltip height is at 100px as expected");
 
   info("Display the tooltip on box2.");
-  await showTooltip(tooltip, box2, {position: "bottom"});
+  yield showTooltip(tooltip, box2, {position: "bottom"});
 
   panelRect = tooltip.container.getBoundingClientRect();
   anchorRect = box2.getBoundingClientRect();
@@ -83,7 +83,7 @@ async function testRtlAnchors(doc, tooltip) {
   is(panelRect.height, TOOLTIP_HEIGHT, "Tooltip height is at 100px as expected");
 }
 
-async function testLtrAnchors(doc, tooltip) {
+function* testLtrAnchors(doc, tooltip) {
     /*
    * The layout of the test page is as follows:
    *   _______________________________
@@ -103,7 +103,7 @@ async function testLtrAnchors(doc, tooltip) {
   let box4 = doc.getElementById("box4");
 
   info("Display the tooltip on box3.");
-  await showTooltip(tooltip, box3, {position: "bottom"});
+  yield showTooltip(tooltip, box3, {position: "bottom"});
 
   let panelRect = tooltip.container.getBoundingClientRect();
   let anchorRect = box3.getBoundingClientRect();
@@ -114,7 +114,7 @@ async function testLtrAnchors(doc, tooltip) {
   is(panelRect.height, TOOLTIP_HEIGHT, "Tooltip height is at 100px as expected");
 
   info("Display the tooltip on box4.");
-  await showTooltip(tooltip, box4, {position: "bottom"});
+  yield showTooltip(tooltip, box4, {position: "bottom"});
 
   panelRect = tooltip.container.getBoundingClientRect();
   anchorRect = box4.getBoundingClientRect();
diff --git a/devtools/client/shared/test/browser_html_tooltip_variable-height.js b/devtools/client/shared/test/browser_html_tooltip_variable-height.js
index 44a3c915613b..8f0b369d6690 100644
--- a/devtools/client/shared/test/browser_html_tooltip_variable-height.js
+++ b/devtools/client/shared/test/browser_html_tooltip_variable-height.js
@@ -18,12 +18,12 @@ const TOOLTIP_HEIGHT = 50;
 const {HTMLTooltip} = require("devtools/client/shared/widgets/tooltip/HTMLTooltip");
 loadHelperScript("helper_html_tooltip.js");
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 400px tall => 50px for each box.
-  await pushPref("devtools.toolbox.footer.height", 400);
+  yield pushPref("devtools.toolbox.footer.height", 400);
 
-  await addTab("about:blank");
-  let [,, doc] = await createHost("bottom", TEST_URI);
+  yield addTab("about:blank");
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   let tooltip = new HTMLTooltip(doc, {useXulWrapper: false});
   info("Set tooltip content 50px tall, but request a container 200px tall");
@@ -32,7 +32,7 @@ add_task(async function () {
   tooltip.setContent(tooltipContent, {width: CONTAINER_WIDTH, height: Infinity});
 
   info("Show the tooltip and check the container and panel height.");
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let containerRect = tooltip.container.getBoundingClientRect();
   let panelRect = tooltip.panel.getBoundingClientRect();
@@ -43,22 +43,22 @@ add_task(async function () {
   info("Click below the tooltip panel but in the tooltip filler element.");
   let onHidden = once(tooltip, "hidden");
   EventUtils.synthesizeMouse(tooltip.container, 100, 100, {}, doc.defaultView);
-  await onHidden;
+  yield onHidden;
 
   info("Show the tooltip one more time, and increase the content height");
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
   tooltipContent.style.height = (2 * CONTAINER_HEIGHT) + "px";
 
   info("Click at the same coordinates as earlier, this time it should hit the tooltip.");
   let onPanelClick = once(tooltip.panel, "click");
   EventUtils.synthesizeMouse(tooltip.container, 100, 100, {}, doc.defaultView);
-  await onPanelClick;
+  yield onPanelClick;
   is(tooltip.isVisible(), true, "Tooltip is still visible");
 
   info("Click above the tooltip container, the tooltip should be closed.");
   onHidden = once(tooltip, "hidden");
   EventUtils.synthesizeMouse(tooltip.container, 100, -10, {}, doc.defaultView);
-  await onHidden;
+  yield onHidden;
 
   tooltip.destroy();
 });
diff --git a/devtools/client/shared/test/browser_html_tooltip_width-auto.js b/devtools/client/shared/test/browser_html_tooltip_width-auto.js
index 76607b5b3599..9ac3705338e0 100644
--- a/devtools/client/shared/test/browser_html_tooltip_width-auto.js
+++ b/devtools/client/shared/test/browser_html_tooltip_width-auto.js
@@ -16,20 +16,20 @@ loadHelperScript("helper_html_tooltip.js");
 
 let useXulWrapper;
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("about:blank");
+  let [,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Run tests for a Tooltip without using a XUL panel");
   useXulWrapper = false;
-  await runTests(doc);
+  yield runTests(doc);
 
   info("Run tests for a Tooltip with a XUL panel");
   useXulWrapper = true;
-  await runTests(doc);
+  yield runTests(doc);
 });
 
-async function runTests(doc) {
+function* runTests(doc) {
   let tooltip = new HTMLTooltip(doc, {useXulWrapper});
   info("Create tooltip content width to 150px");
   let tooltipContent = doc.createElementNS(HTML_NS, "div");
@@ -39,12 +39,12 @@ async function runTests(doc) {
   tooltip.setContent(tooltipContent, {width: "auto", height: 50});
 
   info("Show the tooltip and check the tooltip panel width.");
-  await showTooltip(tooltip, doc.getElementById("box1"));
+  yield showTooltip(tooltip, doc.getElementById("box1"));
 
   let panelRect = tooltip.panel.getBoundingClientRect();
   is(panelRect.width, 150, "Tooltip panel has the expected width.");
 
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   tooltip.destroy();
 }
diff --git a/devtools/client/shared/test/browser_html_tooltip_xul-wrapper.js b/devtools/client/shared/test/browser_html_tooltip_xul-wrapper.js
index 652a2b61d501..31180ee1a16d 100644
--- a/devtools/client/shared/test/browser_html_tooltip_xul-wrapper.js
+++ b/devtools/client/shared/test/browser_html_tooltip_xul-wrapper.js
@@ -20,11 +20,11 @@ loadHelperScript("helper_html_tooltip.js");
 const TOOLTIP_HEIGHT = 160;
 const TOOLTIP_WIDTH = 200;
 
-add_task(async function () {
+add_task(function* () {
   // Force the toolbox to be 200px high;
-  await pushPref("devtools.toolbox.footer.height", 200);
+  yield pushPref("devtools.toolbox.footer.height", 200);
 
-  let [, win, doc] = await createHost("bottom", TEST_URI);
+  let [, win, doc] = yield createHost("bottom", TEST_URI);
 
   info("Resize and move the window to have space below.");
   let originalWidth = win.top.outerWidth;
@@ -51,15 +51,15 @@ add_task(async function () {
 
   // Above box1: check that the tooltip can overflow onto the content page.
   info("Display the tooltip above box1.");
-  await showTooltip(tooltip, box1, {position: "top"});
+  yield showTooltip(tooltip, box1, {position: "top"});
   checkTooltip(tooltip, "top", TOOLTIP_HEIGHT);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   // Below box1: check that the tooltip can overflow out of the browser window.
   info("Display the tooltip below box1.");
-  await showTooltip(tooltip, box1, {position: "bottom"});
+  yield showTooltip(tooltip, box1, {position: "bottom"});
   checkTooltip(tooltip, "bottom", TOOLTIP_HEIGHT);
-  await hideTooltip(tooltip);
+  yield hideTooltip(tooltip);
 
   is(tooltip.isVisible(), false, "Tooltip is not visible");
 
diff --git a/devtools/client/shared/test/browser_inplace-editor-01.js b/devtools/client/shared/test/browser_inplace-editor-01.js
index 35cc7af2736e..4eb4aa0af1f2 100644
--- a/devtools/client/shared/test/browser_inplace-editor-01.js
+++ b/devtools/client/shared/test/browser_inplace-editor-01.js
@@ -9,16 +9,16 @@ loadHelperScript("helper_inplace_editor.js");
 
 // Test the inplace-editor behavior.
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8,inline editor tests");
-  let [host, , doc] = await createHost();
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8,inline editor tests");
+  let [host, , doc] = yield createHost();
 
-  await testMultipleInitialization(doc);
-  await testReturnCommit(doc);
-  await testBlurCommit(doc);
-  await testAdvanceCharCommit(doc);
-  await testAdvanceCharsFunction(doc);
-  await testEscapeCancel(doc);
+  yield testMultipleInitialization(doc);
+  yield testReturnCommit(doc);
+  yield testBlurCommit(doc);
+  yield testAdvanceCharCommit(doc);
+  yield testAdvanceCharsFunction(doc);
+  yield testEscapeCancel(doc);
 
   host.destroy();
   gBrowser.removeCurrentTab();
diff --git a/devtools/client/shared/test/browser_inplace-editor-02.js b/devtools/client/shared/test/browser_inplace-editor-02.js
index b0f45fa94129..811c30123419 100644
--- a/devtools/client/shared/test/browser_inplace-editor-02.js
+++ b/devtools/client/shared/test/browser_inplace-editor-02.js
@@ -9,12 +9,12 @@ loadHelperScript("helper_inplace_editor.js");
 
 // Test that the trimOutput option for the inplace editor works correctly.
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8,inline editor tests");
-  let [host, , doc] = await createHost();
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8,inline editor tests");
+  let [host, , doc] = yield createHost();
 
-  await testNonTrimmed(doc);
-  await testTrimmed(doc);
+  yield testNonTrimmed(doc);
+  yield testTrimmed(doc);
 
   host.destroy();
   gBrowser.removeCurrentTab();
diff --git a/devtools/client/shared/test/browser_inplace-editor_autocomplete_01.js b/devtools/client/shared/test/browser_inplace-editor_autocomplete_01.js
index 158e480cf835..f8c8d88f0bf7 100644
--- a/devtools/client/shared/test/browser_inplace-editor_autocomplete_01.js
+++ b/devtools/client/shared/test/browser_inplace-editor_autocomplete_01.js
@@ -42,14 +42,14 @@ const mockGetCSSPropertyList = function () {
   ];
 };
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8," +
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8," +
     "inplace editor CSS property autocomplete");
-  let [host, win, doc] = await createHost();
+  let [host, win, doc] = yield createHost();
 
   let xulDocument = win.top.document;
   let popup = new AutocompletePopup(xulDocument, { autoSelect: true });
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     createInplaceEditorAndClick({
       start: runPropertyAutocompletionTest,
       contentType: InplaceEditor.CONTENT_TYPES.CSS_PROPERTY,
@@ -63,13 +63,13 @@ add_task(async function () {
   gBrowser.removeCurrentTab();
 });
 
-let runPropertyAutocompletionTest = async function (editor) {
+let runPropertyAutocompletionTest = Task.async(function* (editor) {
   info("Starting to test for css property completion");
   editor._getCSSPropertyList = mockGetCSSPropertyList;
 
   for (let data of testData) {
-    await testCompletion(data, editor);
+    yield testCompletion(data, editor);
   }
 
   EventUtils.synthesizeKey("VK_RETURN", {}, editor.input.defaultView);
-};
+});
diff --git a/devtools/client/shared/test/browser_inplace-editor_autocomplete_02.js b/devtools/client/shared/test/browser_inplace-editor_autocomplete_02.js
index 810aff642795..4f40d0c2be95 100644
--- a/devtools/client/shared/test/browser_inplace-editor_autocomplete_02.js
+++ b/devtools/client/shared/test/browser_inplace-editor_autocomplete_02.js
@@ -43,15 +43,15 @@ const mockGetCSSValuesForPropertyName = function (propertyName) {
   return values[propertyName] || [];
 };
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8," +
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8," +
     "inplace editor CSS value autocomplete");
-  let [host, win, doc] = await createHost();
+  let [host, win, doc] = yield createHost();
 
   let xulDocument = win.top.document;
   let popup = new AutocompletePopup(xulDocument, { autoSelect: true });
 
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     createInplaceEditorAndClick({
       start: runAutocompletionTest,
       contentType: InplaceEditor.CONTENT_TYPES.CSS_VALUE,
@@ -68,13 +68,13 @@ add_task(async function () {
   gBrowser.removeCurrentTab();
 });
 
-let runAutocompletionTest = async function (editor) {
+let runAutocompletionTest = Task.async(function* (editor) {
   info("Starting to test for css property completion");
   editor._getCSSValuesForPropertyName = mockGetCSSValuesForPropertyName;
 
   for (let data of testData) {
-    await testCompletion(data, editor);
+    yield testCompletion(data, editor);
   }
 
   EventUtils.synthesizeKey("VK_RETURN", {}, editor.input.defaultView);
-};
+});
diff --git a/devtools/client/shared/test/browser_inplace-editor_autocomplete_css_variable.js b/devtools/client/shared/test/browser_inplace-editor_autocomplete_css_variable.js
index 91c48894f66e..56231588d9d9 100644
--- a/devtools/client/shared/test/browser_inplace-editor_autocomplete_css_variable.js
+++ b/devtools/client/shared/test/browser_inplace-editor_autocomplete_css_variable.js
@@ -46,15 +46,15 @@ const mockGetCSSVariableNames = function () {
   ];
 };
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8," +
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8," +
     "inplace editor CSS variable autocomplete");
-  let [host, win, doc] = await createHost();
+  let [host, win, doc] = yield createHost();
 
   let xulDocument = win.top.document;
   let popup = new AutocompletePopup(xulDocument, { autoSelect: true });
 
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     createInplaceEditorAndClick({
       start: runAutocompletionTest,
       contentType: InplaceEditor.CONTENT_TYPES.CSS_VALUE,
@@ -71,14 +71,14 @@ add_task(async function () {
   gBrowser.removeCurrentTab();
 });
 
-let runAutocompletionTest = async function (editor) {
+let runAutocompletionTest = Task.async(function* (editor) {
   info("Starting to test for css variable completion");
   editor._getCSSValuesForPropertyName = mockGetCSSValuesForPropertyName;
   editor._getCSSVariableNames = mockGetCSSVariableNames;
 
   for (let data of testData) {
-    await testCompletion(data, editor);
+    yield testCompletion(data, editor);
   }
 
   EventUtils.synthesizeKey("VK_RETURN", {}, editor.input.defaultView);
-};
+});
diff --git a/devtools/client/shared/test/browser_inplace-editor_autocomplete_offset.js b/devtools/client/shared/test/browser_inplace-editor_autocomplete_offset.js
index 1601772786af..9f7cc652675c 100644
--- a/devtools/client/shared/test/browser_inplace-editor_autocomplete_offset.js
+++ b/devtools/client/shared/test/browser_inplace-editor_autocomplete_offset.js
@@ -59,14 +59,14 @@ const mockGetCSSValuesForPropertyName = function (propertyName) {
   return values[propertyName] || [];
 };
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8,inplace editor CSS value autocomplete");
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8,inplace editor CSS value autocomplete");
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let popup = new AutocompletePopup(doc, { autoSelect: true });
 
   info("Create a CSS_MIXED type autocomplete");
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     createInplaceEditorAndClick({
       initial: "style=",
       start: runAutocompletionTest,
@@ -81,7 +81,7 @@ add_task(async function () {
   gBrowser.removeCurrentTab();
 });
 
-let runAutocompletionTest = async function (editor) {
+let runAutocompletionTest = Task.async(function* (editor) {
   info("Starting autocomplete test for inplace-editor popup offset");
   editor._getCSSPropertyList = mockGetCSSPropertyList;
   editor._getCSSValuesForPropertyName = mockGetCSSValuesForPropertyName;
@@ -97,12 +97,12 @@ let runAutocompletionTest = async function (editor) {
       ok(offset > previousOffset, "New popup offset is greater than the previous one");
       previousOffset = offset;
     } else {
-      await testCompletion(data, editor);
+      yield testCompletion(data, editor);
     }
   }
 
   EventUtils.synthesizeKey("VK_RETURN", {}, editor.input.defaultView);
-};
+});
 
 /**
  * Get the autocomplete panel left offset, relative to the provided input's left offset.
diff --git a/devtools/client/shared/test/browser_inplace-editor_maxwidth.js b/devtools/client/shared/test/browser_inplace-editor_maxwidth.js
index 634f3d23a045..887ac10aaeed 100644
--- a/devtools/client/shared/test/browser_inplace-editor_maxwidth.js
+++ b/devtools/client/shared/test/browser_inplace-editor_maxwidth.js
@@ -15,12 +15,12 @@ const LONG_TEXT = "I am a long text and I will not fit in a 300px container. " +
 // Test the inplace-editor behavior with a maxWidth configuration option
 // defined.
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8,inplace editor max width tests");
-  let [host, , doc] = await createHost();
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8,inplace editor max width tests");
+  let [host, , doc] = yield createHost();
 
   info("Testing the maxWidth option in pixels, to precisely check the size");
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     createInplaceEditorAndClick({
       multiline: true,
       maxWidth: MAX_WIDTH,
@@ -33,7 +33,7 @@ add_task(async function () {
   gBrowser.removeCurrentTab();
 });
 
-let testMaxWidth = async function (editor) {
+let testMaxWidth = Task.async(function* (editor) {
   is(editor.input.value, START_TEXT, "Span text content should be used");
   ok(editor.input.offsetWidth < MAX_WIDTH,
     "Input width should be strictly smaller than MAX_WIDTH");
@@ -86,7 +86,7 @@ let testMaxWidth = async function (editor) {
 
   info("Leave the inplace-editor");
   EventUtils.sendKey("RETURN");
-};
+});
 
 /**
  * Retrieve the current number of lines displayed in the provided textarea.
diff --git a/devtools/client/shared/test/browser_key_shortcuts.js b/devtools/client/shared/test/browser_key_shortcuts.js
index e88b68e3ec45..61cb62597f62 100644
--- a/devtools/client/shared/test/browser_key_shortcuts.js
+++ b/devtools/client/shared/test/browser_key_shortcuts.js
@@ -5,28 +5,28 @@
 
 var isOSX = Services.appinfo.OS === "Darwin";
 
-add_task(async function () {
+add_task(function* () {
   let shortcuts = new KeyShortcuts({
     window
   });
 
-  await testSimple(shortcuts);
-  await testNonLetterCharacter(shortcuts);
-  await testPlusCharacter(shortcuts);
-  await testFunctionKey(shortcuts);
-  await testMixup(shortcuts);
-  await testLooseDigits(shortcuts);
-  await testExactModifiers(shortcuts);
-  await testLooseShiftModifier(shortcuts);
-  await testStrictLetterShiftModifier(shortcuts);
-  await testAltModifier(shortcuts);
-  await testCommandOrControlModifier(shortcuts);
-  await testCtrlModifier(shortcuts);
-  await testInvalidShortcutString(shortcuts);
-  await testCmdShiftShortcut(shortcuts);
+  yield testSimple(shortcuts);
+  yield testNonLetterCharacter(shortcuts);
+  yield testPlusCharacter(shortcuts);
+  yield testFunctionKey(shortcuts);
+  yield testMixup(shortcuts);
+  yield testLooseDigits(shortcuts);
+  yield testExactModifiers(shortcuts);
+  yield testLooseShiftModifier(shortcuts);
+  yield testStrictLetterShiftModifier(shortcuts);
+  yield testAltModifier(shortcuts);
+  yield testCommandOrControlModifier(shortcuts);
+  yield testCtrlModifier(shortcuts);
+  yield testInvalidShortcutString(shortcuts);
+  yield testCmdShiftShortcut(shortcuts);
   shortcuts.destroy();
 
-  await testTarget();
+  yield testTarget();
 });
 
 // Test helper to listen to the next key press for a given key,
@@ -45,7 +45,7 @@ function once(shortcuts, key, listener) {
   });
 }
 
-async function testSimple(shortcuts) {
+function* testSimple(shortcuts) {
   info("Test simple key shortcuts");
 
   let onKey = once(shortcuts, "0", event => {
@@ -56,10 +56,10 @@ async function testSimple(shortcuts) {
   });
 
   EventUtils.synthesizeKey("0", {}, window);
-  await onKey;
+  yield onKey;
 }
 
-async function testNonLetterCharacter(shortcuts) {
+function* testNonLetterCharacter(shortcuts) {
   info("Test non-naive character key shortcuts");
 
   let onKey = once(shortcuts, "[", event => {
@@ -67,10 +67,10 @@ async function testNonLetterCharacter(shortcuts) {
   });
 
   EventUtils.synthesizeKey("[", {}, window);
-  await onKey;
+  yield onKey;
 }
 
-async function testFunctionKey(shortcuts) {
+function* testFunctionKey(shortcuts) {
   info("Test function key shortcuts");
 
   let onKey = once(shortcuts, "F12", event => {
@@ -78,13 +78,13 @@ async function testFunctionKey(shortcuts) {
   });
 
   EventUtils.synthesizeKey("F12", { keyCode: 123 }, window);
-  await onKey;
+  yield onKey;
 }
 
 // Plus is special. It's keycode is the one for "=". That's because it requires
 // shift to be pressed and is behind "=" key. So it should be considered as a
 // character key
-async function testPlusCharacter(shortcuts) {
+function* testPlusCharacter(shortcuts) {
   info("Test 'Plus' key shortcuts");
 
   let onKey = once(shortcuts, "Plus", event => {
@@ -92,11 +92,11 @@ async function testPlusCharacter(shortcuts) {
   });
 
   EventUtils.synthesizeKey("+", { keyCode: 61, shiftKey: true }, window);
-  await onKey;
+  yield onKey;
 }
 
 // Test they listeners are not mixed up between shortcuts
-async function testMixup(shortcuts) {
+function* testMixup(shortcuts) {
   info("Test possible listener mixup");
 
   let hitFirst = false, hitSecond = false;
@@ -113,25 +113,25 @@ async function testMixup(shortcuts) {
   // Dispatch the first shortcut and expect only this one to be notified
   ok(!hitFirst, "First shortcut isn't notified before firing the key event");
   EventUtils.synthesizeKey("0", {}, window);
-  await onFirstKey;
+  yield onFirstKey;
   ok(hitFirst, "Got the first shortcut notified");
   ok(!hitSecond, "No mixup, second shortcut is still not notified (1/2)");
 
   // Wait an extra time, just to be sure this isn't racy
-  await new Promise(done => {
+  yield new Promise(done => {
     window.setTimeout(done, 0);
   });
   ok(!hitSecond, "No mixup, second shortcut is still not notified (2/2)");
 
   // Finally dispatch the second shortcut
   EventUtils.synthesizeKey("a", { altKey: true }, window);
-  await onSecondKey;
+  yield onSecondKey;
   ok(hitSecond, "Got the second shortcut notified once it is actually fired");
 }
 
 // On azerty keyboard, digits are only available by pressing Shift/Capslock,
 // but we accept them even if we omit doing that.
-async function testLooseDigits(shortcuts) {
+function* testLooseDigits(shortcuts) {
   info("Test Loose digits");
   let onKey = once(shortcuts, "0", event => {
     is(event.key, "à");
@@ -146,7 +146,7 @@ async function testLooseDigits(shortcuts) {
     "à",
     { keyCode: 48 },
     window);
-  await onKey;
+  yield onKey;
 
   onKey = once(shortcuts, "0", event => {
     is(event.key, "0");
@@ -160,11 +160,11 @@ async function testLooseDigits(shortcuts) {
     "0",
     { keyCode: 48, shiftKey: true },
     window);
-  await onKey;
+  yield onKey;
 }
 
 // Test that shortcuts is notified only when the modifiers match exactly
-async function testExactModifiers(shortcuts) {
+function* testExactModifiers(shortcuts) {
   info("Test exact modifiers match");
 
   let hit = false;
@@ -196,7 +196,7 @@ async function testExactModifiers(shortcuts) {
     window);
 
   // Wait an extra time to let a chance to call the listener
-  await new Promise(done => {
+  yield new Promise(done => {
     window.setTimeout(done, 0);
   });
   ok(!hit, "Listener isn't called when modifiers aren't exactly matching");
@@ -204,7 +204,7 @@ async function testExactModifiers(shortcuts) {
   // Dispatch the expected modifiers
   EventUtils.synthesizeKey("a", { accelKey: false, altKey: true, shiftKey: false},
                            window);
-  await onKey;
+  yield onKey;
   ok(hit, "Got shortcut notified once it is actually fired");
 }
 
@@ -212,7 +212,7 @@ async function testExactModifiers(shortcuts) {
 // even if the key didn't explicitely requested Shift modifier.
 // For example, `%` on french keyboards is only accessible via Shift.
 // Same thing for `@` on US keybords.
-async function testLooseShiftModifier(shortcuts) {
+function* testLooseShiftModifier(shortcuts) {
   info("Test Loose shift modifier");
   let onKey = once(shortcuts, "%", event => {
     is(event.key, "%");
@@ -225,7 +225,7 @@ async function testLooseShiftModifier(shortcuts) {
     "%",
     { accelKey: false, altKey: false, ctrlKey: false, shiftKey: true},
     window);
-  await onKey;
+  yield onKey;
 
   onKey = once(shortcuts, "@", event => {
     is(event.key, "@");
@@ -238,11 +238,11 @@ async function testLooseShiftModifier(shortcuts) {
     "@",
     { accelKey: false, altKey: false, ctrlKey: false, shiftKey: true},
     window);
-  await onKey;
+  yield onKey;
 }
 
 // But Shift modifier is strict on all letter characters (a to Z)
-async function testStrictLetterShiftModifier(shortcuts) {
+function* testStrictLetterShiftModifier(shortcuts) {
   info("Test strict shift modifier on letters");
   let hitFirst = false;
   let onKey = once(shortcuts, "a", event => {
@@ -264,17 +264,17 @@ async function testStrictLetterShiftModifier(shortcuts) {
     "a",
     { shiftKey: true},
     window);
-  await onShiftKey;
+  yield onShiftKey;
   ok(!hitFirst, "Didn't fire the explicit shift+a");
 
   EventUtils.synthesizeKey(
     "a",
     { shiftKey: false},
     window);
-  await onKey;
+  yield onKey;
 }
 
-async function testAltModifier(shortcuts) {
+function* testAltModifier(shortcuts) {
   info("Test Alt modifier");
   let onKey = once(shortcuts, "Alt+F1", event => {
     is(event.keyCode, window.KeyboardEvent.DOM_VK_F1);
@@ -287,10 +287,10 @@ async function testAltModifier(shortcuts) {
     "VK_F1",
     { altKey: true },
     window);
-  await onKey;
+  yield onKey;
 }
 
-async function testCommandOrControlModifier(shortcuts) {
+function* testCommandOrControlModifier(shortcuts) {
   info("Test CommandOrControl modifier");
   let onKey = once(shortcuts, "CommandOrControl+F1", event => {
     is(event.keyCode, window.KeyboardEvent.DOM_VK_F1);
@@ -327,11 +327,11 @@ async function testCommandOrControlModifier(shortcuts) {
       { ctrlKey: true },
       window);
   }
-  await onKey;
-  await onKeyAlias;
+  yield onKey;
+  yield onKeyAlias;
 }
 
-async function testCtrlModifier(shortcuts) {
+function* testCtrlModifier(shortcuts) {
   info("Test Ctrl modifier");
   let onKey = once(shortcuts, "Ctrl+F1", event => {
     is(event.keyCode, window.KeyboardEvent.DOM_VK_F1);
@@ -351,11 +351,11 @@ async function testCtrlModifier(shortcuts) {
     "VK_F1",
     { ctrlKey: true },
     window);
-  await onKey;
-  await onKeyAlias;
+  yield onKey;
+  yield onKeyAlias;
 }
 
-async function testCmdShiftShortcut(shortcuts) {
+function* testCmdShiftShortcut(shortcuts) {
   if (!isOSX) {
     // This test is OSX only (Bug 1300458).
     return;
@@ -385,11 +385,11 @@ async function testCmdShiftShortcut(shortcuts) {
     { metaKey: true },
     window);
 
-  await onCmdKey;
-  await onCmdShiftKey;
+  yield onCmdKey;
+  yield onCmdShiftKey;
 }
 
-async function testTarget() {
+function* testTarget() {
   info("Test KeyShortcuts with target argument");
 
   let target = document.createElementNS("http://www.w3.org/1999/xhtml",
@@ -406,7 +406,7 @@ async function testTarget() {
     is(event.target, target);
   });
   EventUtils.synthesizeKey("0", {}, window);
-  await onKey;
+  yield onKey;
 
   target.remove();
 
diff --git a/devtools/client/shared/test/browser_layoutHelpers.js b/devtools/client/shared/test/browser_layoutHelpers.js
index b9031f2d2eff..a13f1ee6fd50 100644
--- a/devtools/client/shared/test/browser_layoutHelpers.js
+++ b/devtools/client/shared/test/browser_layoutHelpers.js
@@ -8,8 +8,8 @@ const {scrollIntoViewIfNeeded} = require("devtools/client/shared/scroll");
 
 const TEST_URI = TEST_URI_ROOT + "doc_layoutHelpers.html";
 
-add_task(async function () {
-  let [host, win] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host, win] = yield createHost("bottom", TEST_URI);
   runTest(win);
   host.destroy();
 });
diff --git a/devtools/client/shared/test/browser_options-view-01.js b/devtools/client/shared/test/browser_options-view-01.js
index c27c46706483..0ce4119b7af7 100644
--- a/devtools/client/shared/test/browser_options-view-01.js
+++ b/devtools/client/shared/test/browser_options-view-01.js
@@ -14,16 +14,16 @@ const PRETTY_PRINT_PREF = "auto-pretty-print";
 const originalBlackBox = Services.prefs.getBoolPref(BRANCH + BLACK_BOX_PREF);
 const originalPrettyPrint = Services.prefs.getBoolPref(BRANCH + PRETTY_PRINT_PREF);
 
-add_task(async function () {
+add_task(function* () {
   info("Setting a couple of preferences");
   Services.prefs.setBoolPref(BRANCH + BLACK_BOX_PREF, false);
   Services.prefs.setBoolPref(BRANCH + PRETTY_PRINT_PREF, true);
 
   info("Opening a test tab and a toolbox host to create the options view in");
-  await addTab("about:blank");
-  let [host, win] = await createHost("bottom", OPTIONS_VIEW_URL);
+  yield addTab("about:blank");
+  let [host, win] = yield createHost("bottom", OPTIONS_VIEW_URL);
 
-  await testOptionsView(win);
+  yield testOptionsView(win);
 
   info("Closing the host and current tab");
   host.destroy();
@@ -34,10 +34,10 @@ add_task(async function () {
   Services.prefs.setBoolPref(BRANCH + PRETTY_PRINT_PREF, originalPrettyPrint);
 });
 
-async function testOptionsView(win) {
+function* testOptionsView(win) {
   let events = [];
   let options = createOptionsView(win);
-  await options.initialize();
+  yield options.initialize();
 
   let $ = win.document.querySelector.bind(win.document);
 
@@ -68,12 +68,12 @@ async function testOptionsView(win) {
      "correct pref passed in 'pref-changed' event (auto-black-box)");
 
   // Test buttons update when clicked and preferences are updated
-  await click(options, win, ppEl);
+  yield click(options, win, ppEl);
   is(ppEl.getAttribute("checked"), "true", "menuitems update when clicked");
   is(Services.prefs.getBoolPref(BRANCH + PRETTY_PRINT_PREF),
      true, "preference updated via click");
 
-  await click(options, win, bbEl);
+  yield click(options, win, bbEl);
   is(bbEl.getAttribute("checked"), "", "menuitems update when clicked");
   is(Services.prefs.getBoolPref(BRANCH + BLACK_BOX_PREF),
      false, "preference updated via click");
@@ -85,7 +85,7 @@ async function testOptionsView(win) {
   is(events[3], "auto-black-box",
      "correct pref passed in 'pref-changed' event (auto-black-box)");
 
-  await options.destroy();
+  yield options.destroy();
 }
 
 function createOptionsView(win) {
@@ -95,16 +95,16 @@ function createOptionsView(win) {
   });
 }
 
-async function click(view, win, menuitem) {
+function* click(view, win, menuitem) {
   let opened = view.once("options-shown");
   let closed = view.once("options-hidden");
 
   let button = win.document.querySelector("#options-button");
   EventUtils.synthesizeMouseAtCenter(button, {}, win);
-  await opened;
+  yield opened;
   is(button.getAttribute("open"), "true", "button has `open` attribute");
 
   EventUtils.synthesizeMouseAtCenter(menuitem, {}, win);
-  await closed;
+  yield closed;
   ok(!button.hasAttribute("open"), "button does not have `open` attribute");
 }
diff --git a/devtools/client/shared/test/browser_outputparser.js b/devtools/client/shared/test/browser_outputparser.js
index 62c9bd224457..3853b362c37b 100644
--- a/devtools/client/shared/test/browser_outputparser.js
+++ b/devtools/client/shared/test/browser_outputparser.js
@@ -7,19 +7,19 @@ const OutputParser = require("devtools/client/shared/output-parser");
 const {initCssProperties, getCssProperties} = require("devtools/shared/fronts/css-properties");
 const CSS_SHAPES_ENABLED_PREF = "devtools.inspector.shapesHighlighter.enabled";
 
-add_task(async function () {
-  await addTab("about:blank");
-  await performTest();
+add_task(function* () {
+  yield addTab("about:blank");
+  yield performTest();
   gBrowser.removeCurrentTab();
 });
 
-async function performTest() {
-  let [host, , doc] = await createHost("bottom", "data:text/html," +
+function* performTest() {
+  let [host, , doc] = yield createHost("bottom", "data:text/html," +
     "<h1>browser_outputParser.js</h1><div></div>");
 
   // Mock the toolbox that initCssProperties expect so we get the fallback css properties.
   let toolbox = {target: {client: {}, hasActor: () => false}};
-  await initCssProperties(toolbox);
+  yield initCssProperties(toolbox);
   let cssProperties = getCssProperties(toolbox);
 
   let parser = new OutputParser(doc, cssProperties);
diff --git a/devtools/client/shared/test/browser_poller.js b/devtools/client/shared/test/browser_poller.js
index 0b252c0e860f..bb21715e7670 100644
--- a/devtools/client/shared/test/browser_poller.js
+++ b/devtools/client/shared/test/browser_poller.js
@@ -8,7 +8,7 @@
 
 const { Poller } = require("devtools/client/shared/poller");
 
-add_task(async function () {
+add_task(function* () {
   let count1 = 0, count2 = 0, count3 = 0;
 
   let poller1 = new Poller(function () {
@@ -26,26 +26,26 @@ add_task(async function () {
   ok(!poller1.isPolling(), "isPolling() returns false for an off poller");
   ok(poller2.isPolling(), "isPolling() returns true for an on poller");
 
-  await waitUntil(() => count2 > 10);
+  yield waitUntil(() => count2 > 10);
 
   ok(count2 > 10, "poller that was turned on polled several times");
   ok(count1 === 0, "poller that was never turned on never polled");
 
-  await poller2.off();
+  yield poller2.off();
   let currentCount2 = count2;
 
   // Really high poll time!
   poller1.on();
   poller3.on();
 
-  await waitUntil(() => count1 === 1);
+  yield waitUntil(() => count1 === 1);
   ok(true, "Poller calls fn immediately when `immediate` is true");
   ok(count3 === 0, "Poller does not call fn immediately when `immediate` is not set");
 
   ok(count2 === currentCount2, "a turned off poller does not continue to poll");
-  await poller2.off();
-  await poller2.off();
-  await poller2.off();
+  yield poller2.off();
+  yield poller2.off();
+  yield poller2.off();
   ok(true, "Poller.prototype.off() is idempotent");
 
   // This should still have not polled a second time
@@ -55,7 +55,7 @@ add_task(async function () {
   ok(!poller2.isPolling(), "isPolling() returns false for an off poller");
 });
 
-add_task(async function () {
+add_task(function* () {
   let count = -1;
   // Create a poller that returns a promise.
   // The promise is resolved asynchronously after adding 9 to the count, ensuring
@@ -77,11 +77,11 @@ add_task(async function () {
   });
 
   asyncPoller.on(1);
-  await waitUntil(() => count > 50);
-  await asyncPoller.off();
+  yield waitUntil(() => count > 50);
+  yield asyncPoller.off();
 });
 
-add_task(async function () {
+add_task(function* () {
   // Create a poller that returns a promise. This poll call
   // is called immediately, and then subsequently turned off.
   // The call to `off` should not resolve until the inflight call
@@ -99,13 +99,13 @@ add_task(async function () {
   }, 1, true);
   asyncPoller.on();
 
-  await asyncPoller.off();
+  yield asyncPoller.off();
   ok(inflightFinished,
      "off() method does not resolve until remaining inflight poll calls finish");
   is(pollCalls, 1, "should only be one poll call to occur before turning off polling");
 });
 
-add_task(async function () {
+add_task(function* () {
   // Create a poller that returns a promise. This poll call
   // is called immediately, and then subsequently turned off.
   // The call to `off` should not resolve until the inflight call
@@ -123,7 +123,7 @@ add_task(async function () {
   }, 1, true);
   asyncPoller.on();
 
-  await asyncPoller.destroy();
+  yield asyncPoller.destroy();
   ok(inflightFinished,
      "destroy() method does not resolve until remaining inflight poll calls finish");
   is(pollCalls, 1, "should only be one poll call to occur before destroying polling");
diff --git a/devtools/client/shared/test/browser_spectrum.js b/devtools/client/shared/test/browser_spectrum.js
index 46752c624b2c..b75e58accfff 100644
--- a/devtools/client/shared/test/browser_spectrum.js
+++ b/devtools/client/shared/test/browser_spectrum.js
@@ -10,16 +10,16 @@ const {Spectrum} = require("devtools/client/shared/widgets/Spectrum");
 
 const TEST_URI = CHROME_URL_ROOT + "doc_spectrum.html";
 
-add_task(async function () {
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let container = doc.getElementById("spectrum-container");
 
-  await testCreateAndDestroyShouldAppendAndRemoveElements(container);
-  await testPassingAColorAtInitShouldSetThatColor(container);
-  await testSettingAndGettingANewColor(container);
-  await testChangingColorShouldEmitEvents(container);
-  await testSettingColorShoudUpdateTheUI(container);
+  yield testCreateAndDestroyShouldAppendAndRemoveElements(container);
+  yield testPassingAColorAtInitShouldSetThatColor(container);
+  yield testSettingAndGettingANewColor(container);
+  yield testChangingColorShouldEmitEvents(container);
+  yield testSettingColorShoudUpdateTheUI(container);
 
   host.destroy();
 });
diff --git a/devtools/client/shared/test/browser_tableWidget_basic.js b/devtools/client/shared/test/browser_tableWidget_basic.js
index a0f8268ded29..e64a9890a14c 100644
--- a/devtools/client/shared/test/browser_tableWidget_basic.js
+++ b/devtools/client/shared/test/browser_tableWidget_basic.js
@@ -10,9 +10,9 @@ const TEST_URI = CHROME_URL_ROOT + "doc_tableWidget_basic.html";
 
 const {TableWidget} = require("devtools/client/shared/widgets/TableWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [host, , doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("about:blank");
+  let [host, , doc] = yield createHost("bottom", TEST_URI);
 
   let table = new TableWidget(doc.querySelector("box"), {
     initialColumns: {
diff --git a/devtools/client/shared/test/browser_tableWidget_keyboard_interaction.js b/devtools/client/shared/test/browser_tableWidget_keyboard_interaction.js
index dc7e1c9bc49f..5b81a4efab3c 100644
--- a/devtools/client/shared/test/browser_tableWidget_keyboard_interaction.js
+++ b/devtools/client/shared/test/browser_tableWidget_keyboard_interaction.js
@@ -44,11 +44,11 @@ function endTests() {
   finish();
 }
 
-var startTests = async function () {
+var startTests = Task.async(function* () {
   populateTable();
-  await testKeyboardInteraction();
+  yield testKeyboardInteraction();
   endTests();
-};
+});
 
 function populateTable() {
   table.push({
@@ -131,35 +131,35 @@ function getNodeByValue(value) {
  * Tests if pressing navigation keys on the table items does the expected
  * behavior.
  */
-var testKeyboardInteraction = async function () {
+var testKeyboardInteraction = Task.async(function* () {
   info("Testing keyboard interaction with the table");
   info("clicking on the row containing id2");
   let node = getNodeByValue("id2");
   let event = table.once(TableWidget.EVENTS.ROW_SELECTED);
   click(node);
-  await event;
+  yield event;
 
-  await testRow("id3", "DOWN", "next row");
-  await testRow("id4", "DOWN", "next row");
-  await testRow("id3", "UP", "previous row");
-  await testRow("id4", "DOWN", "next row");
-  await testRow("id5", "DOWN", "next row");
-  await testRow("id6", "DOWN", "next row");
-  await testRow("id5", "UP", "previous row");
-  await testRow("id4", "UP", "previous row");
-  await testRow("id3", "UP", "previous row");
+  yield testRow("id3", "DOWN", "next row");
+  yield testRow("id4", "DOWN", "next row");
+  yield testRow("id3", "UP", "previous row");
+  yield testRow("id4", "DOWN", "next row");
+  yield testRow("id5", "DOWN", "next row");
+  yield testRow("id6", "DOWN", "next row");
+  yield testRow("id5", "UP", "previous row");
+  yield testRow("id4", "UP", "previous row");
+  yield testRow("id3", "UP", "previous row");
 
   // selecting last item node to test edge navigation cycling case
   table.selectedRow = "id9";
 
   // pressing down on last row should move to first row.
-  await testRow("id1", "DOWN", "first row");
+  yield testRow("id1", "DOWN", "first row");
 
   // pressing up now should move to last row.
-  await testRow("id9", "UP", "last row");
-};
+  yield testRow("id9", "UP", "last row");
+});
 
-async function testRow(id, key, destination) {
+function* testRow(id, key, destination) {
   let node = getNodeByValue(id);
   // node should not have selected class
   ok(!node.classList.contains("theme-selected"),
@@ -169,7 +169,7 @@ async function testRow(id, key, destination) {
   let event = table.once(TableWidget.EVENTS.ROW_SELECTED);
   EventUtils.sendKey(key, doc.defaultView);
 
-  let uniqueId = await event;
+  let uniqueId = yield event;
   is(id, uniqueId, `Correct row was selected after pressing ${key}`);
 
   ok(node.classList.contains("theme-selected"), "row has selected class");
diff --git a/devtools/client/shared/test/browser_tableWidget_mouse_interaction.js b/devtools/client/shared/test/browser_tableWidget_mouse_interaction.js
index 7b53978d44ba..726151b6fa2a 100644
--- a/devtools/client/shared/test/browser_tableWidget_mouse_interaction.js
+++ b/devtools/client/shared/test/browser_tableWidget_mouse_interaction.js
@@ -45,11 +45,11 @@ function endTests() {
   finish();
 }
 
-var startTests = async function () {
+var startTests = Task.async(function* () {
   populateTable();
-  await testMouseInteraction();
+  yield testMouseInteraction();
   endTests();
-};
+});
 
 function populateTable() {
   table.push({
@@ -127,7 +127,7 @@ function click(node, button = 0) {
 /**
  * Tests if clicking the table items does the expected behavior
  */
-var testMouseInteraction = async function () {
+var testMouseInteraction = Task.async(function* () {
   info("Testing mouse interaction with the table");
   ok(!table.selectedRow, "Nothing should be selected beforehand");
 
@@ -137,7 +137,7 @@ var testMouseInteraction = async function () {
   ok(!firstColumnFirstRowCell.classList.contains("theme-selected"),
      "Node should not have selected class before clicking");
   click(firstColumnFirstRowCell);
-  let id = await event;
+  let id = yield event;
   ok(firstColumnFirstRowCell.classList.contains("theme-selected"),
      "Node has selected class after click");
   is(id, "id1", "Correct row was selected");
@@ -149,7 +149,7 @@ var testMouseInteraction = async function () {
   ok(!firstColumnSecondRowCell.classList.contains("theme-selected"),
      "New node should not have selected class before clicking");
   click(firstColumnSecondRowCell);
-  id = await event;
+  id = yield event;
   ok(firstColumnSecondRowCell.classList.contains("theme-selected"),
      "New node has selected class after clicking");
   is(id, "id2", "Correct table path is emitted for new node");
@@ -166,7 +166,7 @@ var testMouseInteraction = async function () {
   ok(!firstColumnThirdRowCell.classList.contains("theme-selected"),
      "New node should not have selected class before clicking");
   click(firstColumnThirdRowCellInnerNode);
-  id = await event;
+  id = yield event;
   ok(firstColumnThirdRowCell.classList.contains("theme-selected"),
      "New node has selected class after clicking the cell content");
   is(id, "id3", "Correct table path is emitted for new node");
@@ -181,7 +181,7 @@ var testMouseInteraction = async function () {
      "Although, something else should be sorted on");
   isnot(doc.querySelector("[sorted]"), node, "Which is not equal to this node");
   click(node);
-  id = await event;
+  id = yield event;
   is(id, "col4", "Correct column was sorted on");
   ok(node.hasAttribute("sorted"),
      "Node should now have sorted attribute after clicking");
@@ -196,7 +196,7 @@ var testMouseInteraction = async function () {
   node = table.tbody.firstChild.firstChild.firstChild;
   let onPopupShown = once(table.menupopup, "popupshown");
   click(node, 2);
-  await onPopupShown;
+  yield onPopupShown;
 
   is(table.menupopup.querySelectorAll("[disabled]").length, 1,
      "Only 1 menuitem is disabled");
@@ -212,8 +212,8 @@ var testMouseInteraction = async function () {
   ok(!table.tbody.children[2].hasAttribute("hidden"),
      "Column is not hidden before hiding it");
   click(node);
-  id = await event;
-  await onPopupHidden;
+  id = yield event;
+  yield onPopupHidden;
   is(id, "col2", "Correct column was triggered to be hidden");
   is(table.tbody.children[2].getAttribute("hidden"), "true",
      "Column is hidden after hiding it");
@@ -224,7 +224,7 @@ var testMouseInteraction = async function () {
   node = table.tbody.firstChild.firstChild.firstChild;
   onPopupShown = once(table.menupopup, "popupshown");
   click(node, 2);
-  await onPopupShown;
+  yield onPopupShown;
 
   is(table.menupopup.querySelectorAll("[disabled]").length, 1,
      "Only 1 menuitem is disabled");
@@ -237,8 +237,8 @@ var testMouseInteraction = async function () {
   ok(!table.tbody.children[4].hasAttribute("hidden"),
      "Column is not hidden before hiding it");
   click(node);
-  id = await event;
-  await onPopupHidden;
+  id = yield event;
+  yield onPopupHidden;
   is(id, "col3", "Correct column was triggered to be hidden");
   is(table.tbody.children[4].getAttribute("hidden"), "true",
      "Column is hidden after hiding it");
@@ -249,7 +249,7 @@ var testMouseInteraction = async function () {
   node = table.tbody.firstChild.firstChild.firstChild;
   onPopupShown = once(table.menupopup, "popupshown");
   click(node, 2);
-  await onPopupShown;
+  yield onPopupShown;
 
   is(table.menupopup.querySelectorAll("[disabled]").length, 2,
      "2 menuitems are disabled now as only 2 columns remain visible");
@@ -270,8 +270,8 @@ var testMouseInteraction = async function () {
   is(table.tbody.children[2].getAttribute("hidden"), "true",
      "Column is hidden before unhiding it");
   click(node);
-  id = await event;
-  await onPopupHidden;
+  id = yield event;
+  yield onPopupHidden;
   is(id, "col2", "Correct column was triggered to be hidden");
   ok(!table.tbody.children[2].hasAttribute("hidden"),
      "Column is not hidden after unhiding it");
@@ -282,7 +282,7 @@ var testMouseInteraction = async function () {
   node = table.tbody.firstChild.firstChild.firstChild;
   onPopupShown = once(table.menupopup, "popupshown");
   click(node, 2);
-  await onPopupShown;
+  yield onPopupShown;
 
   // popup should be open now
   // clicking on second column label
@@ -293,8 +293,8 @@ var testMouseInteraction = async function () {
   is(table.tbody.children[4].getAttribute("hidden"), "true",
      "Column is hidden before unhiding it");
   click(node);
-  id = await event;
-  await onPopupHidden;
+  id = yield event;
+  yield onPopupHidden;
   is(id, "col3", "Correct column was triggered to be hidden");
   ok(!table.tbody.children[4].hasAttribute("hidden"),
      "Column is not hidden after unhiding it");
@@ -302,4 +302,4 @@ var testMouseInteraction = async function () {
   // reset table state
   table.clearSelection();
   table.sortBy("col1");
-};
+});
diff --git a/devtools/client/shared/test/browser_telemetry_button_eyedropper.js b/devtools/client/shared/test/browser_telemetry_button_eyedropper.js
index 3f68ec23b6a0..95966bd2ee5b 100644
--- a/devtools/client/shared/test/browser_telemetry_button_eyedropper.js
+++ b/devtools/client/shared/test/browser_telemetry_button_eyedropper.js
@@ -6,27 +6,27 @@ const TEST_URI = "data:text/html;charset=utf-8," +
   "<p>browser_telemetry_button_eyedropper.js</p><div>test</div>";
 const EYEDROPPER_OPENED = "devtools.toolbar.eyedropper.opened";
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "inspector");
+  let toolbox = yield gDevTools.showToolbox(target, "inspector");
   info("inspector opened");
 
   info("testing the eyedropper button");
-  await testButton(toolbox, Telemetry);
+  yield testButton(toolbox, Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   gBrowser.removeCurrentTab();
 });
 
-async function testButton(toolbox, Telemetry) {
+function* testButton(toolbox, Telemetry) {
   info("Calling the eyedropper button's callback");
   // We call the button callback directly because we don't need to test the UI here, we're
   // only concerned about testing the telemetry probe.
-  await toolbox.getPanel("inspector").showEyeDropper();
+  yield toolbox.getPanel("inspector").showEyeDropper();
 
   checkTelemetryResults(Telemetry);
 }
diff --git a/devtools/client/shared/test/browser_telemetry_button_paintflashing.js b/devtools/client/shared/test/browser_telemetry_button_paintflashing.js
index 3c94dc8da83b..20da52b424a7 100644
--- a/devtools/client/shared/test/browser_telemetry_button_paintflashing.js
+++ b/devtools/client/shared/test/browser_telemetry_button_paintflashing.js
@@ -11,36 +11,36 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
-  await pushPref("devtools.command-button-paintflashing.enabled", true);
+  yield pushPref("devtools.command-button-paintflashing.enabled", true);
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "inspector");
+  let toolbox = yield gDevTools.showToolbox(target, "inspector");
   info("inspector opened");
 
   info("testing the paintflashing button");
-  await testButton(toolbox, Telemetry);
+  yield testButton(toolbox, Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   gBrowser.removeCurrentTab();
 });
 
-async function testButton(toolbox, Telemetry) {
+function* testButton(toolbox, Telemetry) {
   info("Testing command-button-paintflashing");
 
   let button = toolbox.doc.querySelector("#command-button-paintflashing");
   ok(button, "Captain, we have the button");
 
-  await delayedClicks(toolbox, button, 4);
+  yield* delayedClicks(toolbox, button, 4);
   checkResults("_PAINTFLASHING_", Telemetry);
 }
 
-async function delayedClicks(toolbox, node, clicks) {
+function* delayedClicks(toolbox, node, clicks) {
   for (let i = 0; i < clicks; i++) {
-    await new Promise(resolve => {
+    yield new Promise(resolve => {
       // See TOOL_DELAY for why we need setTimeout here
       setTimeout(() => resolve(), TOOL_DELAY);
     });
@@ -58,7 +58,7 @@ async function delayedClicks(toolbox, node, clicks) {
     info("Clicking button " + node.id);
     node.click();
 
-    await clicked;
+    yield clicked;
   }
 }
 
diff --git a/devtools/client/shared/test/browser_telemetry_button_responsive.js b/devtools/client/shared/test/browser_telemetry_button_responsive.js
index ea4fc160e90f..2e17511d88cc 100644
--- a/devtools/client/shared/test/browser_telemetry_button_responsive.js
+++ b/devtools/client/shared/test/browser_telemetry_button_responsive.js
@@ -32,29 +32,29 @@ registerCleanupFunction(() => {
 
 loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsive.html/manager", true);
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "inspector");
+  let toolbox = yield gDevTools.showToolbox(target, "inspector");
   info("inspector opened");
 
   info("testing the responsivedesign button");
-  await testButton(toolbox, Telemetry);
+  yield testButton(toolbox, Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   gBrowser.removeCurrentTab();
 });
 
-async function testButton(toolbox, Telemetry) {
+function* testButton(toolbox, Telemetry) {
   info("Testing command-button-responsive");
 
   let button = toolbox.doc.querySelector("#command-button-responsive");
   ok(button, "Captain, we have the button");
 
-  await delayedClicks(button, 4);
+  yield delayedClicks(button, 4);
 
   checkResults("_RESPONSIVE_", Telemetry);
 }
@@ -71,16 +71,16 @@ function waitForToggle() {
   });
 }
 
-var delayedClicks = async function (node, clicks) {
+var delayedClicks = Task.async(function* (node, clicks) {
   for (let i = 0; i < clicks; i++) {
     info("Clicking button " + node.id);
     let toggled = waitForToggle();
     node.click();
-    await toggled;
+    yield toggled;
     // See TOOL_DELAY for why we need setTimeout here
-    await DevToolsUtils.waitForTime(TOOL_DELAY);
+    yield DevToolsUtils.waitForTime(TOOL_DELAY);
   }
-};
+});
 
 function checkResults(histIdFocus, Telemetry) {
   let result = Telemetry.prototype.telemetryInfo;
diff --git a/devtools/client/shared/test/browser_telemetry_button_scratchpad.js b/devtools/client/shared/test/browser_telemetry_button_scratchpad.js
index 83ce23ebe167..94309f603943 100644
--- a/devtools/client/shared/test/browser_telemetry_button_scratchpad.js
+++ b/devtools/client/shared/test/browser_telemetry_button_scratchpad.js
@@ -11,26 +11,26 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await pushPref("devtools.command-button-scratchpad.enabled", true);
+  yield pushPref("devtools.command-button-scratchpad.enabled", true);
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "inspector");
+  let toolbox = yield gDevTools.showToolbox(target, "inspector");
   info("inspector opened");
 
   let onAllWindowsOpened = trackScratchpadWindows();
 
   info("testing the scratchpad button");
-  await testButton(toolbox, Telemetry);
-  await onAllWindowsOpened;
+  yield testButton(toolbox, Telemetry);
+  yield onAllWindowsOpened;
 
   checkResults("_SCRATCHPAD_", Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   gBrowser.removeCurrentTab();
 });
 
@@ -68,12 +68,12 @@ function trackScratchpadWindows() {
   });
 }
 
-async function testButton(toolbox, Telemetry) {
+function* testButton(toolbox, Telemetry) {
   info("Testing command-button-scratchpad");
   let button = toolbox.doc.querySelector("#command-button-scratchpad");
   ok(button, "Captain, we have the button");
 
-  await delayedClicks(button, 4);
+  yield delayedClicks(button, 4);
 }
 
 function delayedClicks(node, clicks) {
diff --git a/devtools/client/shared/test/browser_telemetry_sidebar.js b/devtools/client/shared/test/browser_telemetry_sidebar.js
index e855e7e49933..021409f65f47 100644
--- a/devtools/client/shared/test/browser_telemetry_sidebar.js
+++ b/devtools/client/shared/test/browser_telemetry_sidebar.js
@@ -10,23 +10,23 @@ const TEST_URI = "data:text/html;charset=utf-8,<p>browser_telemetry_sidebar.js</
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "inspector");
+  let toolbox = yield gDevTools.showToolbox(target, "inspector");
   info("inspector opened");
 
-  await testSidebar(toolbox);
+  yield testSidebar(toolbox);
   checkResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
-  await gDevTools.closeToolbox(target);
+  yield gDevTools.closeToolbox(target);
   gBrowser.removeCurrentTab();
 });
 
-function testSidebar(toolbox) {
+function* testSidebar(toolbox) {
   info("Testing sidebar");
 
   let inspector = toolbox.getCurrentPanel();
diff --git a/devtools/client/shared/test/browser_telemetry_toolbox.js b/devtools/client/shared/test/browser_telemetry_toolbox.js
index 388c856216c7..85328cf14ad3 100644
--- a/devtools/client/shared/test/browser_telemetry_toolbox.js
+++ b/devtools/client/shared/test/browser_telemetry_toolbox.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(3, TOOL_DELAY, "inspector");
+  yield openAndCloseToolbox(3, TOOL_DELAY, "inspector");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_canvasdebugger.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_canvasdebugger.js
index 9c4f56dcfeca..81ab9470ce70 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_canvasdebugger.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_canvasdebugger.js
@@ -10,15 +10,15 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
+add_task(function* () {
   info("Activate the canvasdebugger");
   let originalPref = Services.prefs.getBoolPref("devtools.canvasdebugger.enabled");
   Services.prefs.setBoolPref("devtools.canvasdebugger.enabled", true);
 
-  await addTab(TEST_URI);
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "canvasdebugger");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "canvasdebugger");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_inspector.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_inspector.js
index 788cace85c6d..a50c8d203725 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_inspector.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_inspector.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "inspector");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "inspector");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsdebugger.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsdebugger.js
index 1fc1f21df64e..ba1c26643923 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsdebugger.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsdebugger.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "jsdebugger");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "jsdebugger");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsprofiler.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsprofiler.js
index 8c0607993a99..0a5dfb0487b2 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsprofiler.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_jsprofiler.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "performance");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "performance");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_netmonitor.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_netmonitor.js
index 999385bdfe9d..6d5292b1174d 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_netmonitor.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_netmonitor.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "netmonitor");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "netmonitor");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_options.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_options.js
index 9bb9dbab653e..26b3bf77c64b 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_options.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_options.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "options");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "options");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_shadereditor.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_shadereditor.js
index 38f621fd0040..4829362fac57 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_shadereditor.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_shadereditor.js
@@ -11,15 +11,15 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 const TOOL_DELAY = 200;
 const TOOL_PREF = "devtools.shadereditor.enabled";
 
-add_task(async function () {
+add_task(function* () {
   info("Active the sharer editor");
   let originalPref = Services.prefs.getBoolPref(TOOL_PREF);
   Services.prefs.setBoolPref(TOOL_PREF, true);
 
-  await addTab(TEST_URI);
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "shadereditor");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "shadereditor");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_storage.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_storage.js
index 3ca1967dbd26..8dd16513de71 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_storage.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_storage.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 1000;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "storage");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "storage");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_styleeditor.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_styleeditor.js
index befec410fb11..cdd9e3fb3b07 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_styleeditor.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_styleeditor.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "styleeditor");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "styleeditor");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_webaudioeditor.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_webaudioeditor.js
index b43446571ddc..a75ebad1d1b3 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_webaudioeditor.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_webaudioeditor.js
@@ -10,15 +10,15 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
+add_task(function* () {
   info("Activating the webaudioeditor");
   let originalPref = Services.prefs.getBoolPref("devtools.webaudioeditor.enabled");
   Services.prefs.setBoolPref("devtools.webaudioeditor.enabled", true);
 
-  await addTab(TEST_URI);
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "webaudioeditor");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "webaudioeditor");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_telemetry_toolboxtabs_webconsole.js b/devtools/client/shared/test/browser_telemetry_toolboxtabs_webconsole.js
index 49d131a0e54a..4e15dbf4be00 100644
--- a/devtools/client/shared/test/browser_telemetry_toolboxtabs_webconsole.js
+++ b/devtools/client/shared/test/browser_telemetry_toolboxtabs_webconsole.js
@@ -10,11 +10,11 @@ const TEST_URI = "data:text/html;charset=utf-8," +
 // opened we make use of setTimeout() to create tool active times.
 const TOOL_DELAY = 200;
 
-add_task(async function () {
-  await addTab(TEST_URI);
+add_task(function* () {
+  yield addTab(TEST_URI);
   let Telemetry = loadTelemetryAndRecordLogs();
 
-  await openAndCloseToolbox(2, TOOL_DELAY, "webconsole");
+  yield openAndCloseToolbox(2, TOOL_DELAY, "webconsole");
   checkTelemetryResults(Telemetry);
 
   stopRecordingTelemetryLogs(Telemetry);
diff --git a/devtools/client/shared/test/browser_templater_basic.js b/devtools/client/shared/test/browser_templater_basic.js
index e450f292cf3f..7c947d0b1539 100644
--- a/devtools/client/shared/test/browser_templater_basic.js
+++ b/devtools/client/shared/test/browser_templater_basic.js
@@ -15,13 +15,13 @@ const {template} = require("devtools/shared/gcli/templater");
 
 const TEST_URI = TEST_URI_ROOT + "doc_templater_basic.html";
 
-var test = async function () {
-  await addTab("about:blank");
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+var test = Task.async(function* () {
+  yield addTab("about:blank");
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   info("Starting DOM Templater Tests");
   runTest(0, host, doc);
-};
+});
 
 function runTest(index, host, doc) {
   let options = tests[index] = tests[index]();
diff --git a/devtools/client/shared/test/browser_theme_switching.js b/devtools/client/shared/test/browser_theme_switching.js
index 27a9e2a2c0e5..392462a677a9 100644
--- a/devtools/client/shared/test/browser_theme_switching.js
+++ b/devtools/client/shared/test/browser_theme_switching.js
@@ -4,9 +4,9 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target);
+  let toolbox = yield gDevTools.showToolbox(target);
   let doc = toolbox.doc;
   let root = doc.documentElement;
 
@@ -39,7 +39,7 @@ add_task(async function () {
        "There is a stylesheet for " + themeSheet);
   }
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
 });
 
 function getPlatform() {
diff --git a/devtools/client/shared/test/browser_toolbar_basic.js b/devtools/client/shared/test/browser_toolbar_basic.js
index a3a64f6a1419..f57d2d2306d3 100644
--- a/devtools/client/shared/test/browser_toolbar_basic.js
+++ b/devtools/client/shared/test/browser_toolbar_basic.js
@@ -14,16 +14,16 @@ const {gDevToolsBrowser} = require("devtools/client/framework/devtools-browser")
 
 const TEST_URI = TEST_URI_ROOT + "doc_toolbar_basic.html";
 
-add_task(async function () {
+add_task(function* () {
   info("Starting browser_toolbar_basic.js");
-  await addTab(TEST_URI);
+  yield addTab(TEST_URI);
 
   let toolbar = gDevToolsBrowser.getDeveloperToolbar(window);
   ok(!toolbar.visible, "DeveloperToolbar is not visible in to start");
 
   let shown = oneTimeObserve(toolbar.NOTIFICATIONS.SHOW);
   document.getElementById("menu_devToolbar").doCommand();
-  await shown;
+  yield shown;
   ok(toolbar.visible, "DeveloperToolbar is visible in checkOpen");
 
   let close = document.getElementById("developer-toolbar-closebutton");
@@ -34,10 +34,10 @@ add_task(async function () {
   ok(!isChecked(toggleToolbox), "toggle toolbox button is not checked");
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  await gDevTools.showToolbox(target, "inspector");
+  yield gDevTools.showToolbox(target, "inspector");
   ok(isChecked(toggleToolbox), "toggle toolbox button is checked");
 
-  await addTab("about:blank");
+  yield addTab("about:blank");
   info("Opened a new tab");
 
   ok(!isChecked(toggleToolbox), "toggle toolbox button is not checked");
@@ -46,19 +46,19 @@ add_task(async function () {
 
   let hidden = oneTimeObserve(toolbar.NOTIFICATIONS.HIDE);
   document.getElementById("menu_devToolbar").doCommand();
-  await hidden;
+  yield hidden;
   ok(!toolbar.visible, "DeveloperToolbar is not visible in hidden");
 
   shown = oneTimeObserve(toolbar.NOTIFICATIONS.SHOW);
   document.getElementById("menu_devToolbar").doCommand();
-  await shown;
+  yield shown;
   ok(toolbar.visible, "DeveloperToolbar is visible in after open");
 
   ok(isChecked(toggleToolbox), "toggle toolbox button is checked");
 
   hidden = oneTimeObserve(toolbar.NOTIFICATIONS.HIDE);
   document.getElementById("developer-toolbar-closebutton").doCommand();
-  await hidden;
+  yield hidden;
 
   ok(!toolbar.visible, "DeveloperToolbar is not visible after re-close");
 });
diff --git a/devtools/client/shared/test/browser_toolbar_tooltip.js b/devtools/client/shared/test/browser_toolbar_tooltip.js
index 61f2fce80e55..965f92573b30 100644
--- a/devtools/client/shared/test/browser_toolbar_tooltip.js
+++ b/devtools/client/shared/test/browser_toolbar_tooltip.js
@@ -17,8 +17,8 @@ registerCleanupFunction(() => {
 
 let toolbar = gDevToolsBrowser.getDeveloperToolbar(window);
 
-add_task(async function showToolbar() {
-  await addTab(TEST_URI);
+add_task(function* showToolbar() {
+  yield addTab(TEST_URI);
 
   info("Starting browser_toolbar_tooltip.js");
 
@@ -26,14 +26,14 @@ add_task(async function showToolbar() {
 
   let showPromise = observeOnce(toolbar.NOTIFICATIONS.SHOW);
   document.getElementById("menu_devToolbar").doCommand();
-  await showPromise;
+  yield showPromise;
 });
 
-add_task(async function testDimensions() {
+add_task(function* testDimensions() {
   let tooltipPanel = toolbar.tooltipPanel;
 
   toolbar.focusManager.helpRequest();
-  await toolbar.inputter.setInput("help help");
+  yield toolbar.inputter.setInput("help help");
 
   toolbar.inputter.setCursor({ start: "help help".length });
   is(tooltipPanel._dimensions.start, "help ".length,
@@ -56,35 +56,35 @@ add_task(async function testDimensions() {
   ok(getLeftMargin() > 9, "tooltip offset, when cursor at start");
 });
 
-add_task(async function testThemes() {
+add_task(function* testThemes() {
   let tooltipPanel = toolbar.tooltipPanel;
   ok(tooltipPanel.document, "Tooltip panel is initialized");
 
   Services.prefs.setCharPref(PREF_DEVTOOLS_THEME, "dark");
 
-  await toolbar.inputter.setInput("");
-  await toolbar.inputter.setInput("help help");
+  yield toolbar.inputter.setInput("");
+  yield toolbar.inputter.setInput("help help");
   is(tooltipPanel.document.documentElement.getAttribute("devtoolstheme"),
      "dark", "Tooltip panel has correct theme");
 
   Services.prefs.setCharPref(PREF_DEVTOOLS_THEME, "light");
 
-  await toolbar.inputter.setInput("");
-  await toolbar.inputter.setInput("help help");
+  yield toolbar.inputter.setInput("");
+  yield toolbar.inputter.setInput("help help");
   is(tooltipPanel.document.documentElement.getAttribute("devtoolstheme"),
      "light", "Tooltip panel has correct theme");
 });
 
-add_task(async function hideToolbar() {
+add_task(function* hideToolbar() {
   info("Ending browser_toolbar_tooltip.js");
-  await toolbar.inputter.setInput("");
+  yield toolbar.inputter.setInput("");
 
   ok(toolbar.visible, "DeveloperToolbar is visible in hideToolbar");
 
   info("Hide toolbar");
   let hidePromise = observeOnce(toolbar.NOTIFICATIONS.HIDE);
   document.getElementById("menu_devToolbar").doCommand();
-  await hidePromise;
+  yield hidePromise;
 
   ok(!toolbar.visible, "DeveloperToolbar is not visible in hideToolbar");
 
diff --git a/devtools/client/shared/test/browser_treeWidget_basic.js b/devtools/client/shared/test/browser_treeWidget_basic.js
index 52b651711dda..b1d7772f7255 100644
--- a/devtools/client/shared/test/browser_treeWidget_basic.js
+++ b/devtools/client/shared/test/browser_treeWidget_basic.js
@@ -10,9 +10,9 @@ const TEST_URI = "data:text/html;charset=utf-8,<head>" +
   "ets.css'></head><body><div></div><span></span></body>";
 const {TreeWidget} = require("devtools/client/shared/widgets/TreeWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("about:blank");
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let tree = new TreeWidget(doc.querySelector("div"), {
     defaultType: "store"
diff --git a/devtools/client/shared/test/browser_treeWidget_mouse_interaction.js b/devtools/client/shared/test/browser_treeWidget_mouse_interaction.js
index 3efd8e000cf9..ce3d047ad75d 100644
--- a/devtools/client/shared/test/browser_treeWidget_mouse_interaction.js
+++ b/devtools/client/shared/test/browser_treeWidget_mouse_interaction.js
@@ -11,16 +11,16 @@ const TEST_URI = "data:text/html;charset=utf-8,<head>" +
   "ets.css'></head><body><div></div><span></span></body>";
 const {TreeWidget} = require("devtools/client/shared/widgets/TreeWidget");
 
-add_task(async function () {
-  await addTab("about:blank");
-  let [host,, doc] = await createHost("bottom", TEST_URI);
+add_task(function* () {
+  yield addTab("about:blank");
+  let [host,, doc] = yield createHost("bottom", TEST_URI);
 
   let tree = new TreeWidget(doc.querySelector("div"), {
     defaultType: "store"
   });
 
   populateTree(tree, doc);
-  await testMouseInteraction(tree);
+  yield testMouseInteraction(tree);
 
   tree.destroy();
   host.destroy();
@@ -83,7 +83,7 @@ function click(node) {
 /**
  * Tests if clicking the tree items does the expected behavior
  */
-async function testMouseInteraction(tree) {
+function* testMouseInteraction(tree) {
   info("Testing mouse interaction with the tree");
   let event;
   let pass = (d, a) => event.resolve([d, a]);
@@ -97,7 +97,7 @@ async function testMouseInteraction(tree) {
   ok(!node.classList.contains("theme-selected"),
      "Node should not have selected class before clicking");
   click(node);
-  let [data, attachment] = await event.promise;
+  let [data, attachment] = yield event.promise;
   ok(node.classList.contains("theme-selected"),
      "Node has selected class after click");
   is(data[0], "level1.2", "Correct tree path is emitted");
@@ -113,7 +113,7 @@ async function testMouseInteraction(tree) {
   ok(!node2.hasAttribute("expanded"), "New node is not expanded before clicking");
   tree.once("select", pass);
   click(node2);
-  [data, attachment] = await event.promise;
+  [data, attachment] = yield event.promise;
   ok(node2.classList.contains("theme-selected"),
      "New node has selected class after clicking");
   is(data[0], "level1", "Correct tree path is emitted for new node");
@@ -130,6 +130,6 @@ async function testMouseInteraction(tree) {
     executeSoon(() => event.resolve(null));
   }, { once: true });
   click(node2);
-  await event.promise;
+  yield event.promise;
   ok(!node2.hasAttribute("expanded"), "New node collapsed after click again");
 }
diff --git a/devtools/client/shared/test/frame-script-utils.js b/devtools/client/shared/test/frame-script-utils.js
index 752c7056ba9b..5dc1b4d92ee9 100644
--- a/devtools/client/shared/test/frame-script-utils.js
+++ b/devtools/client/shared/test/frame-script-utils.js
@@ -6,6 +6,7 @@
 /* global addMessageListener, sendAsyncMessage, content */
 "use strict";
 const {require} = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
+const { Task } = require("devtools/shared/task");
 const Services = require("Services");
 
 addMessageListener("devtools:test:history", function ({ data }) {
@@ -100,17 +101,17 @@ function promiseXHR(data) {
  *   response: XMLHttpRequest.response
  * }
  */
-addMessageListener("devtools:test:xhr", async function ({ data }) {
+addMessageListener("devtools:test:xhr", Task.async(function* ({ data }) {
   let requests = Array.isArray(data) ? data : [data];
   let responses = [];
 
   for (let request of requests) {
-    let response = await promiseXHR(request);
+    let response = yield promiseXHR(request);
     responses.push(response);
   }
 
   sendAsyncMessage("devtools:test:xhr", responses);
-});
+}));
 
 addMessageListener("devtools:test:profiler", function ({ data }) {
   let { method, args, id } = data;
diff --git a/devtools/client/shared/test/head.js b/devtools/client/shared/test/head.js
index 2b71eef1fedd..adbc5506e0ac 100644
--- a/devtools/client/shared/test/head.js
+++ b/devtools/client/shared/test/head.js
@@ -105,18 +105,18 @@ function oneTimeObserve(name, callback) {
 }
 
 let createHost =
-async function (type = "bottom", src = CHROME_URL_ROOT + "dummy.html") {
+Task.async(function* (type = "bottom", src = CHROME_URL_ROOT + "dummy.html") {
   let host = new Hosts[type](gBrowser.selectedTab);
-  let iframe = await host.create();
+  let iframe = yield host.create();
 
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     let domHelper = new DOMHelpers(iframe.contentWindow);
     iframe.setAttribute("src", src);
     domHelper.onceDOMReady(resolve);
   });
 
   return [host, iframe.contentWindow, iframe.contentDocument];
-};
+});
 
 /**
  * Check the correctness of the data recorded in Telemetry after
@@ -155,17 +155,17 @@ function checkTelemetryResults(Telemetry) {
  * @param {Number} usageTime in milliseconds
  * @param {String} toolId
  */
-async function openAndCloseToolbox(nbOfTimes, usageTime, toolId) {
+function* openAndCloseToolbox(nbOfTimes, usageTime, toolId) {
   for (let i = 0; i < nbOfTimes; i++) {
     info("Opening toolbox " + (i + 1));
     let target = TargetFactory.forTab(gBrowser.selectedTab);
-    await gDevTools.showToolbox(target, toolId);
+    yield gDevTools.showToolbox(target, toolId);
 
     // We use a timeout to check the toolbox's active time
-    await new Promise(resolve => setTimeout(resolve, usageTime));
+    yield new Promise(resolve => setTimeout(resolve, usageTime));
 
     info("Closing toolbox " + (i + 1));
-    await gDevTools.closeToolbox(target);
+    yield gDevTools.closeToolbox(target);
   }
 }
 
@@ -225,12 +225,12 @@ function showFilterPopupPresets(widget) {
  * @return {Promise}
  */
 let showFilterPopupPresetsAndCreatePreset =
-async function (widget, name, value) {
-  await showFilterPopupPresets(widget);
+Task.async(function* (widget, name, value) {
+  yield showFilterPopupPresets(widget);
 
   let onRender = widget.once("render");
   widget.setCssValue(value);
-  await onRender;
+  yield onRender;
 
   let footer = widget.el.querySelector(".presets-list .footer");
   footer.querySelector("input").value = name;
@@ -240,5 +240,5 @@ async function (widget, name, value) {
     preventDefault: () => {}
   });
 
-  await onRender;
-};
+  yield onRender;
+});
diff --git a/devtools/client/shared/test/helper_html_tooltip.js b/devtools/client/shared/test/helper_html_tooltip.js
index ef8bab5a0c60..ffc6945f3059 100644
--- a/devtools/client/shared/test/helper_html_tooltip.js
+++ b/devtools/client/shared/test/helper_html_tooltip.js
@@ -20,10 +20,10 @@
  * @return {Promise} promise that resolves when "shown" has been fired, reflow
  *         and repaint done.
  */
-async function showTooltip(tooltip, anchor, {position, x, y} = {}) {
+function* showTooltip(tooltip, anchor, {position, x, y} = {}) {
   let onShown = tooltip.once("shown");
   tooltip.show(anchor, {position, x, y});
-  await onShown;
+  yield onShown;
   return waitForReflow(tooltip);
 }
 
@@ -36,10 +36,10 @@ async function showTooltip(tooltip, anchor, {position, x, y} = {}) {
  * @return {Promise} promise that resolves when "hidden" has been fired, reflow
  *         and repaint done.
  */
-async function hideTooltip(tooltip) {
+function* hideTooltip(tooltip) {
   let onPopupHidden = tooltip.once("hidden");
   tooltip.hide();
-  await onPopupHidden;
+  yield onPopupHidden;
   return waitForReflow(tooltip);
 }
 
diff --git a/devtools/client/shared/test/helper_inplace_editor.js b/devtools/client/shared/test/helper_inplace_editor.js
index f4e1acc0b170..623c2208ae05 100644
--- a/devtools/client/shared/test/helper_inplace_editor.js
+++ b/devtools/client/shared/test/helper_inplace_editor.js
@@ -23,7 +23,7 @@ const { editableField } = require("devtools/client/shared/inplace-editor");
  * @param {String} textContent
  *        (optional) String that will be used as the text content of the span.
  */
-const createInplaceEditorAndClick = async function (options, doc, textContent) {
+const createInplaceEditorAndClick = Task.async(function* (options, doc, textContent) {
   let span = options.element = createSpan(doc);
   if (textContent) {
     span.textContent = textContent;
@@ -34,7 +34,7 @@ const createInplaceEditorAndClick = async function (options, doc, textContent) {
 
   info("Clicking on the inplace-editor field to turn to edit mode");
   span.click();
-};
+});
 
 /**
  * Helper to create a span in the provided document.
@@ -75,7 +75,7 @@ function createSpan(doc) {
  * @param {InplaceEditor} editor
  *        The InplaceEditor instance being tested
  */
-async function testCompletion([key, completion, index, total], editor) {
+function* testCompletion([key, completion, index, total], editor) {
   info("Pressing key " + key);
   info("Expecting " + completion);
 
@@ -97,9 +97,9 @@ async function testCompletion([key, completion, index, total], editor) {
   info("Synthesizing key " + key);
   EventUtils.synthesizeKey(key, {}, editor.input.defaultView);
 
-  await onSuggest;
-  await onVisibilityChange;
-  await waitForTime(5);
+  yield onSuggest;
+  yield onVisibilityChange;
+  yield waitForTime(5);
 
   info("Checking the state");
   if (completion !== null) {
diff --git a/devtools/client/shared/test/shared-head.js b/devtools/client/shared/test/shared-head.js
index 1dee0f56dce2..56def015c860 100644
--- a/devtools/client/shared/test/shared-head.js
+++ b/devtools/client/shared/test/shared-head.js
@@ -29,6 +29,7 @@ const flags = require("devtools/shared/flags");
 let promise = require("promise");
 let defer = require("devtools/shared/defer");
 const Services = require("Services");
+const {Task} = require("devtools/shared/task");
 const KeyShortcuts = require("devtools/client/shared/key-shortcuts");
 
 const TEST_DIR = gTestPath.substr(0, gTestPath.lastIndexOf("/"));
@@ -119,9 +120,9 @@ registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.toolbox.splitconsoleHeight");
 });
 
-registerCleanupFunction(async function cleanup() {
+registerCleanupFunction(function* cleanup() {
   while (gBrowser.tabs.length > 1) {
-    await closeTabAndToolbox(gBrowser.selectedTab);
+    yield closeTabAndToolbox(gBrowser.selectedTab);
   }
 });
 
@@ -135,7 +136,7 @@ registerCleanupFunction(async function cleanup() {
  *   - {String} preferredRemoteType
  * @return a promise that resolves to the tab object when the url is loaded
  */
-var addTab = async function (url, options = { background: false, window: window }) {
+var addTab = Task.async(function* (url, options = { background: false, window: window }) {
   info("Adding a new tab with URL: " + url);
 
   let { background } = options;
@@ -147,28 +148,28 @@ var addTab = async function (url, options = { background: false, window: window
   if (!background) {
     gBrowser.selectedTab = tab;
   }
-  await BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+  yield BrowserTestUtils.browserLoaded(tab.linkedBrowser);
 
   info("Tab added and finished loading");
 
   return tab;
-};
+});
 
 /**
  * Remove the given tab.
  * @param {Object} tab The tab to be removed.
  * @return Promise<undefined> resolved when the tab is successfully removed.
  */
-var removeTab = async function (tab) {
+var removeTab = Task.async(function* (tab) {
   info("Removing tab.");
 
   let { gBrowser } = tab.ownerDocument.defaultView;
   let onClose = once(gBrowser.tabContainer, "TabClose");
   gBrowser.removeTab(tab);
-  await onClose;
+  yield onClose;
 
   info("Tab removed and finished closing");
-};
+});
 
 /**
  * Refresh the provided tab.
@@ -377,12 +378,12 @@ function wait(ms) {
  * @param {String} hostType Optional. The type of toolbox host to be used.
  * @return {Promise} Resolves with the toolbox, when it has been opened.
  */
-var openToolboxForTab = async function (tab, toolId, hostType) {
+var openToolboxForTab = Task.async(function* (tab, toolId, hostType) {
   info("Opening the toolbox");
 
   let toolbox;
   let target = TargetFactory.forTab(tab);
-  await target.makeRemote();
+  yield target.makeRemote();
 
   // Check if the toolbox is already loaded.
   toolbox = gDevTools.getToolbox(target);
@@ -394,15 +395,15 @@ var openToolboxForTab = async function (tab, toolId, hostType) {
   }
 
   // If not, load it now.
-  toolbox = await gDevTools.showToolbox(target, toolId, hostType);
+  toolbox = yield gDevTools.showToolbox(target, toolId, hostType);
 
   // Make sure that the toolbox frame is focused.
-  await new Promise(resolve => waitForFocus(resolve, toolbox.win));
+  yield new Promise(resolve => waitForFocus(resolve, toolbox.win));
 
   info("Toolbox opened and focused");
 
   return toolbox;
-};
+});
 
 /**
  * Add a new tab and open the toolbox in it.
@@ -412,10 +413,10 @@ var openToolboxForTab = async function (tab, toolId, hostType) {
  * @return {Promise} Resolves when the tab has been added, loaded and the
  * toolbox has been opened. Resolves to the toolbox.
  */
-var openNewTabAndToolbox = async function (url, toolId, hostType) {
-  let tab = await addTab(url);
+var openNewTabAndToolbox = Task.async(function* (url, toolId, hostType) {
+  let tab = yield addTab(url);
   return openToolboxForTab(tab, toolId, hostType);
-};
+});
 
 /**
  * Close a tab and if necessary, the toolbox that belongs to it
@@ -423,14 +424,14 @@ var openNewTabAndToolbox = async function (url, toolId, hostType) {
  * @return {Promise} Resolves when the toolbox and tab have been destroyed and
  * closed.
  */
-var closeTabAndToolbox = async function (tab = gBrowser.selectedTab) {
+var closeTabAndToolbox = Task.async(function* (tab = gBrowser.selectedTab) {
   let target = TargetFactory.forTab(tab);
   if (target) {
-    await gDevTools.closeToolbox(target);
+    yield gDevTools.closeToolbox(target);
   }
 
-  await removeTab(tab);
-};
+  yield removeTab(tab);
+});
 
 /**
  * Close a toolbox and the current tab.
@@ -438,10 +439,10 @@ var closeTabAndToolbox = async function (tab = gBrowser.selectedTab) {
  * @return {Promise} Resolves when the toolbox and tab have been destroyed and
  * closed.
  */
-var closeToolboxAndTab = async function (toolbox) {
-  await toolbox.destroy();
-  await removeTab(gBrowser.selectedTab);
-};
+var closeToolboxAndTab = Task.async(function* (toolbox) {
+  yield toolbox.destroy();
+  yield removeTab(gBrowser.selectedTab);
+});
 
 /**
  * Waits until a predicate returns true.
@@ -578,10 +579,10 @@ function lookupPath(obj, path) {
   return segments.reduce((prev, current) => prev[current], obj);
 }
 
-var closeToolbox = async function () {
+var closeToolbox = Task.async(function* () {
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  await gDevTools.closeToolbox(target);
-};
+  yield gDevTools.closeToolbox(target);
+});
 
 /**
  * Load the Telemetry utils, then stub Telemetry.prototype.log and
@@ -683,12 +684,12 @@ function createTestHTTPServer() {
   const {HttpServer} = ChromeUtils.import("resource://testing-common/httpd.js", {});
   let server = new HttpServer();
 
-  registerCleanupFunction(async function cleanup() {
+  registerCleanupFunction(function* cleanup() {
     let destroyed = defer();
     server.stop(() => {
       destroyed.resolve();
     });
-    await destroyed.promise;
+    yield destroyed.promise;
   });
 
   server.start(-1);
@@ -706,7 +707,7 @@ function createTestHTTPServer() {
  *        Reference to the browser in which we load content task
  */
 async function injectEventUtilsInContentTask(browser) {
-  await ContentTask.spawn(browser, {}, async function () {
+  await ContentTask.spawn(browser, {}, function* () {
     if ("EventUtils" in this) {
       return;
     }
diff --git a/devtools/client/shared/test/test-actor-registry.js b/devtools/client/shared/test/test-actor-registry.js
index ff3d6e9e4269..949548611948 100644
--- a/devtools/client/shared/test/test-actor-registry.js
+++ b/devtools/client/shared/test/test-actor-registry.js
@@ -8,14 +8,15 @@
 
   const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
   const { fetch } = require("devtools/shared/DevToolsUtils");
+  const { Task } = require("devtools/shared/task");
 
   const TEST_URL_ROOT = "http://example.com/browser/devtools/client/shared/test/";
   const ACTOR_URL = TEST_URL_ROOT + "test-actor.js";
 
   // Register a test actor that can operate on the remote document
-  exports.registerTestActor = async function (client) {
+  exports.registerTestActor = Task.async(function* (client) {
     // First, instanciate ActorRegistryFront to be able to dynamically register an actor
-    let response = await client.listTabs();
+    let response = yield client.listTabs();
     let { ActorRegistryFront } = require("devtools/shared/fronts/actor-registry");
     let registryFront = ActorRegistryFront(client, response);
 
@@ -25,20 +26,20 @@
       constructor: "TestActor",
       prefix: "testActor"
     };
-    let testActorFront = await registryFront.registerActor(ACTOR_URL, options);
+    let testActorFront = yield registryFront.registerActor(ACTOR_URL, options);
     return testActorFront;
-  };
+  });
 
   // Load the test actor in a custom sandbox as we can't use SDK module loader with URIs
-  let loadFront = async function () {
-    let sourceText = await request(ACTOR_URL);
+  let loadFront = Task.async(function* () {
+    let sourceText = yield request(ACTOR_URL);
     const principal = CC("@mozilla.org/systemprincipal;1", "nsIPrincipal")();
     const sandbox = Cu.Sandbox(principal);
     sandbox.exports = {};
     sandbox.require = require;
     Cu.evalInSandbox(sourceText, sandbox, "1.8", ACTOR_URL, 1);
     return sandbox.exports;
-  };
+  });
 
   // Ensure fetching a live TabActor form for the targeted app
   // (helps fetching the test actor registered dynamically)
@@ -48,14 +49,14 @@
   };
 
   // Spawn an instance of the test actor for the given toolbox
-  exports.getTestActor = async function (toolbox) {
+  exports.getTestActor = Task.async(function* (toolbox) {
     let client = toolbox.target.client;
     return getTestActor(client, toolbox.target.tab, toolbox);
-  };
+  });
 
   // Sometimes, we need the test actor before opening or without a toolbox then just
   // create a front for the given `tab`
-  exports.getTestActorWithoutToolbox = async function (tab) {
+  exports.getTestActorWithoutToolbox = Task.async(function* (tab) {
     let { DebuggerServer } = require("devtools/server/main");
     let { DebuggerClient } = require("devtools/shared/client/debugger-client");
 
@@ -65,26 +66,26 @@
     DebuggerServer.registerAllActors();
     let client = new DebuggerClient(DebuggerServer.connectPipe());
 
-    await client.connect();
+    yield client.connect();
 
     // We also need to make sure the test actor is registered on the server.
-    await exports.registerTestActor(client);
+    yield exports.registerTestActor(client);
 
     return getTestActor(client, tab);
-  };
+  });
 
   // Fetch the content of a URI
   let request = function (uri) {
     return fetch(uri).then(({ content }) => content);
   };
 
-  let getTestActor = async function (client, tab, toolbox) {
+  let getTestActor = Task.async(function* (client, tab, toolbox) {
     // We may have to update the form in order to get the dynamically registered
     // test actor.
-    let form = await getUpdatedForm(client, tab);
+    let form = yield getUpdatedForm(client, tab);
 
-    let { TestActorFront } = await loadFront();
+    let { TestActorFront } = yield loadFront();
 
     return new TestActorFront(client, form, toolbox);
-  };
+  });
 })(this);
diff --git a/devtools/client/shared/test/test-actor.js b/devtools/client/shared/test/test-actor.js
index 77b4174dd0ee..5ca8ac193795 100644
--- a/devtools/client/shared/test/test-actor.js
+++ b/devtools/client/shared/test/test-actor.js
@@ -14,6 +14,7 @@ const {
   getRect, getAdjustedQuads, getWindowDimensions
 } = require("devtools/shared/layout/utils");
 const defer = require("devtools/shared/defer");
+const {Task} = require("devtools/shared/task");
 const {
   isContentStylesheet,
   getCSSStyleRules
@@ -702,16 +703,16 @@ var TestActor = exports.TestActor = protocol.ActorClassWithSpec(testSpec, {
     return deferred.promise;
   },
 
-  async getNodeRect(selector) {
+  getNodeRect: Task.async(function* (selector) {
     let node = this._querySelector(selector);
     return getRect(this.content, node, this.content);
-  },
+  }),
 
-  async getTextNodeRect(parentSelector, childNodeIndex) {
+  getTextNodeRect: Task.async(function* (parentSelector, childNodeIndex) {
     let parentNode = this._querySelector(parentSelector);
     let node = parentNode.childNodes[childNodeIndex];
     return getAdjustedQuads(this.content, node)[0].bounds;
-  },
+  }),
 
   /**
    * Get information about a DOM element, identified by a selector.
@@ -850,11 +851,11 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
    * @param {String} prefix An optional prefix for logging information to the
    * console.
    */
-  async isNodeCorrectlyHighlighted(selector, is, prefix = "") {
+  isNodeCorrectlyHighlighted: Task.async(function* (selector, is, prefix = "") {
     prefix += (prefix ? " " : "") + selector + " ";
 
-    let boxModel = await this._getBoxModelStatus();
-    let regions = await this.getAllAdjustedQuads(selector);
+    let boxModel = yield this._getBoxModelStatus();
+    let regions = yield this.getAllAdjustedQuads(selector);
 
     for (let boxType of ["content", "padding", "border", "margin"]) {
       let [quad] = regions[boxType];
@@ -865,13 +866,13 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
           prefix + boxType + " point " + point + " y coordinate is correct");
       }
     }
-  },
+  }),
 
   /**
    * Get the current rect of the border region of the box-model highlighter
    */
-  async getSimpleBorderRect(toolbox) {
-    let {border} = await this._getBoxModelStatus(toolbox);
+  getSimpleBorderRect: Task.async(function* (toolbox) {
+    let {border} = yield this._getBoxModelStatus(toolbox);
     let {p1, p2, p4} = border.points;
 
     return {
@@ -880,32 +881,32 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
       width: p2.x - p1.x,
       height: p4.y - p1.y
     };
-  },
+  }),
 
   /**
    * Get the current positions and visibility of the various box-model highlighter
    * elements.
    */
-  async _getBoxModelStatus() {
-    let isVisible = await this.isHighlighting();
+  _getBoxModelStatus: Task.async(function* () {
+    let isVisible = yield this.isHighlighting();
 
     let ret = {
       visible: isVisible
     };
 
     for (let region of ["margin", "border", "padding", "content"]) {
-      let points = await this._getPointsForRegion(region);
-      let visible = await this._isRegionHidden(region);
+      let points = yield this._getPointsForRegion(region);
+      let visible = yield this._isRegionHidden(region);
       ret[region] = {points, visible};
     }
 
     ret.guides = {};
     for (let guide of ["top", "right", "bottom", "left"]) {
-      ret.guides[guide] = await this._getGuideStatus(guide);
+      ret.guides[guide] = yield this._getGuideStatus(guide);
     }
 
     return ret;
-  },
+  }),
 
   /**
    * Check that the box-model highlighter is currently highlighting the node matching the
@@ -913,10 +914,10 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
    * @param {String} selector
    * @return {Boolean}
    */
-  async assertHighlightedNode(selector) {
-    let rect = await this.getNodeRect(selector);
-    return this.isNodeRectHighlighted(rect);
-  },
+  assertHighlightedNode: Task.async(function* (selector) {
+    let rect = yield this.getNodeRect(selector);
+    return yield this.isNodeRectHighlighted(rect);
+  }),
 
   /**
    * Check that the box-model highlighter is currently highlighting the text node that can
@@ -926,18 +927,18 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
    * @param {Number} childNodeIndex
    * @return {Boolean}
    */
-  async assertHighlightedTextNode(parentSelector, childNodeIndex) {
-    let rect = await this.getTextNodeRect(parentSelector, childNodeIndex);
-    return this.isNodeRectHighlighted(rect);
-  },
+  assertHighlightedTextNode: Task.async(function* (parentSelector, childNodeIndex) {
+    let rect = yield this.getTextNodeRect(parentSelector, childNodeIndex);
+    return yield this.isNodeRectHighlighted(rect);
+  }),
 
   /**
    * Check that the box-model highlighter is currently highlighting the given rect.
    * @param {Object} rect
    * @return {Boolean}
    */
-  async isNodeRectHighlighted({ left, top, width, height }) {
-    let {visible, border} = await this._getBoxModelStatus();
+  isNodeRectHighlighted: Task.async(function* ({ left, top, width, height }) {
+    let {visible, border} = yield this._getBoxModelStatus();
     let points = border.points;
     if (!visible) {
       return false;
@@ -960,14 +961,14 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
            isInside([right, top], points) &&
            isInside([right, bottom], points) &&
            isInside([left, bottom], points);
-  },
+  }),
 
   /**
    * Get the coordinate (points attribute) from one of the polygon elements in the
    * box model highlighter.
    */
-  async _getPointsForRegion(region) {
-    let d = await this.getHighlighterNodeAttribute("box-model-" + region, "d");
+  _getPointsForRegion: Task.async(function* (region) {
+    let d = yield this.getHighlighterNodeAttribute("box-model-" + region, "d");
 
     let polygons = d.match(/M[^M]+/g);
     if (!polygons) {
@@ -996,25 +997,25 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
         y: parseFloat(points[3][1])
       }
     };
-  },
+  }),
 
   /**
    * Is a given region polygon element of the box-model highlighter currently
    * hidden?
    */
-  async _isRegionHidden(region) {
-    let value = await this.getHighlighterNodeAttribute("box-model-" + region, "hidden");
+  _isRegionHidden: Task.async(function* (region) {
+    let value = yield this.getHighlighterNodeAttribute("box-model-" + region, "hidden");
     return value !== null;
-  },
+  }),
 
-  async _getGuideStatus(location) {
+  _getGuideStatus: Task.async(function* (location) {
     let id = "box-model-guide-" + location;
 
-    let hidden = await this.getHighlighterNodeAttribute(id, "hidden");
-    let x1 = await this.getHighlighterNodeAttribute(id, "x1");
-    let y1 = await this.getHighlighterNodeAttribute(id, "y1");
-    let x2 = await this.getHighlighterNodeAttribute(id, "x2");
-    let y2 = await this.getHighlighterNodeAttribute(id, "y2");
+    let hidden = yield this.getHighlighterNodeAttribute(id, "hidden");
+    let x1 = yield this.getHighlighterNodeAttribute(id, "x1");
+    let y1 = yield this.getHighlighterNodeAttribute(id, "y1");
+    let x2 = yield this.getHighlighterNodeAttribute(id, "x2");
+    let y2 = yield this.getHighlighterNodeAttribute(id, "y2");
 
     return {
       visible: !hidden,
@@ -1023,7 +1024,7 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
       x2: x2,
       y2: y2
     };
-  },
+  }),
 
   /**
    * Get the coordinates of the rectangle that is defined by the 4 guides displayed
@@ -1031,11 +1032,11 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
    * @return {Object} Null if at least one guide is hidden. Otherwise an object
    * with p1, p2, p3, p4 properties being {x, y} objects.
    */
-  async getGuidesRectangle() {
-    let tGuide = await this._getGuideStatus("top");
-    let rGuide = await this._getGuideStatus("right");
-    let bGuide = await this._getGuideStatus("bottom");
-    let lGuide = await this._getGuideStatus("left");
+  getGuidesRectangle: Task.async(function* () {
+    let tGuide = yield this._getGuideStatus("top");
+    let rGuide = yield this._getGuideStatus("right");
+    let bGuide = yield this._getGuideStatus("bottom");
+    let lGuide = yield this._getGuideStatus("left");
 
     if (!tGuide.visible || !rGuide.visible || !bGuide.visible || !lGuide.visible) {
       return null;
@@ -1047,7 +1048,7 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
       p3: {x: +rGuide.x1 + 1, y: +bGuide.y1 + 1},
       p4: {x: lGuide.x1, y: +bGuide.y1 + 1}
     };
-  },
+  }),
 
   waitForHighlighterEvent: protocol.custom(function (event) {
     return this._waitForHighlighterEvent(event, this.toolbox.highlighter.actorID);
@@ -1065,8 +1066,8 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
    * - points {Array} an array of all the polygons defined by the path. Each box
    *   is itself an Array of points, themselves being [x,y] coordinates arrays.
    */
-  async getHighlighterRegionPath(region, highlighter) {
-    let d = await this.getHighlighterNodeAttribute(
+  getHighlighterRegionPath: Task.async(function* (region, highlighter) {
+    let d = yield this.getHighlighterNodeAttribute(
       `box-model-${region}`, "d", highlighter
     );
     if (!d) {
@@ -1086,7 +1087,7 @@ var TestActorFront = exports.TestActorFront = protocol.FrontClassWithSpec(testSp
     }
 
     return {d, points};
-  }
+  })
 });
 
 /**
diff --git a/devtools/client/shared/view-source.js b/devtools/client/shared/view-source.js
index fb6822ab93a4..94a6dffa2281 100644
--- a/devtools/client/shared/view-source.js
+++ b/devtools/client/shared/view-source.js
@@ -4,6 +4,8 @@
 
 "use strict";
 
+var { Task } = require("devtools/shared/task");
+
 var Services = require("Services");
 var { gDevTools } = require("devtools/client/framework/devtools");
 var { getSourceText } = require("devtools/client/debugger/content/queries");
@@ -21,19 +23,19 @@ var { getSourceText } = require("devtools/client/debugger/content/queries");
  *
  * @return {Promise<boolean>}
  */
-exports.viewSourceInStyleEditor = async function (toolbox, sourceURL,
+exports.viewSourceInStyleEditor = Task.async(function* (toolbox, sourceURL,
                                                         sourceLine) {
-  let panel = await toolbox.loadTool("styleeditor");
+  let panel = yield toolbox.loadTool("styleeditor");
 
   try {
-    await panel.selectStyleSheet(sourceURL, sourceLine);
-    await toolbox.selectTool("styleeditor");
+    yield panel.selectStyleSheet(sourceURL, sourceLine);
+    yield toolbox.selectTool("styleeditor");
     return true;
   } catch (e) {
     exports.viewSource(toolbox, sourceURL, sourceLine);
     return false;
   }
-};
+});
 
 /**
  * Tries to open a JavaScript file in the Debugger. If the file is not found,
@@ -48,18 +50,18 @@ exports.viewSourceInStyleEditor = async function (toolbox, sourceURL,
  *
  * @return {Promise<boolean>}
  */
-exports.viewSourceInDebugger = async function (toolbox, sourceURL, sourceLine) {
+exports.viewSourceInDebugger = Task.async(function* (toolbox, sourceURL, sourceLine) {
   // If the Debugger was already open, switch to it and try to show the
   // source immediately. Otherwise, initialize it and wait for the sources
   // to be added first.
   let debuggerAlreadyOpen = toolbox.getPanel("jsdebugger");
-  let dbg = await toolbox.loadTool("jsdebugger");
+  let dbg = yield toolbox.loadTool("jsdebugger");
 
   // New debugger frontend
   if (Services.prefs.getBoolPref("devtools.debugger.new-debugger-frontend")) {
     const source = dbg.getSource(sourceURL);
     if (source) {
-      await toolbox.selectTool("jsdebugger");
+      yield toolbox.selectTool("jsdebugger");
       dbg.selectSource(sourceURL, sourceLine);
       return true;
     }
@@ -72,7 +74,7 @@ exports.viewSourceInDebugger = async function (toolbox, sourceURL, sourceLine) {
 
   // Old debugger frontend
   if (!debuggerAlreadyOpen) {
-    await win.DebuggerController.waitForSourcesLoaded();
+    yield win.DebuggerController.waitForSourcesLoaded();
   }
 
   let { DebuggerView } = win;
@@ -80,7 +82,7 @@ exports.viewSourceInDebugger = async function (toolbox, sourceURL, sourceLine) {
 
   let item = Sources.getItemForAttachment(a => a.source.url === sourceURL);
   if (item) {
-    await toolbox.selectTool("jsdebugger");
+    yield toolbox.selectTool("jsdebugger");
 
     // Determine if the source has already finished loading. There's two cases
     // in which we need to wait for the source to be shown:
@@ -110,7 +112,7 @@ exports.viewSourceInDebugger = async function (toolbox, sourceURL, sourceLine) {
 
     // Wait for it to load
     if (!isSelected || isLoading) {
-      await win.DebuggerController.waitForSourceShown(sourceURL);
+      yield win.DebuggerController.waitForSourceShown(sourceURL);
     }
     return true;
   }
@@ -118,7 +120,7 @@ exports.viewSourceInDebugger = async function (toolbox, sourceURL, sourceLine) {
   // If not found, still attempt to open in View Source
   exports.viewSource(toolbox, sourceURL, sourceLine);
   return false;
-};
+});
 
 /**
  * Tries to open a JavaScript file in the corresponding Scratchpad.
@@ -128,7 +130,7 @@ exports.viewSourceInDebugger = async function (toolbox, sourceURL, sourceLine) {
  *
  * @return {Promise}
  */
-exports.viewSourceInScratchpad = async function (sourceURL, sourceLine) {
+exports.viewSourceInScratchpad = Task.async(function* (sourceURL, sourceLine) {
   // Check for matching top level scratchpad window.
   let wins = Services.wm.getEnumerator("devtools:scratchpad");
 
@@ -156,7 +158,7 @@ exports.viewSourceInScratchpad = async function (sourceURL, sourceLine) {
       }
     }
   }
-};
+});
 
 /**
  * Open a link in Firefox's View Source.
@@ -167,10 +169,10 @@ exports.viewSourceInScratchpad = async function (sourceURL, sourceLine) {
  *
  * @return {Promise}
  */
-exports.viewSource = async function (toolbox, sourceURL, sourceLine) {
+exports.viewSource = Task.async(function* (toolbox, sourceURL, sourceLine) {
   let utils = toolbox.gViewSourceUtils;
   utils.viewSource({
     URL: sourceURL,
     lineNumber: sourceLine || 0,
   });
-};
+});
diff --git a/devtools/client/shared/widgets/ColorWidget.js b/devtools/client/shared/widgets/ColorWidget.js
index b20b55683c09..7566012ee6a8 100644
--- a/devtools/client/shared/widgets/ColorWidget.js
+++ b/devtools/client/shared/widgets/ColorWidget.js
@@ -9,6 +9,7 @@
 
 "use strict";
 
+const {Task} = require("devtools/shared/task");
 const EventEmitter = require("devtools/shared/event-emitter");
 const {colorUtils} = require("devtools/shared/css/color");
 const {LocalizationHelper} = require("devtools/shared/l10n");
@@ -385,7 +386,7 @@ ColorWidget.prototype = {
     this.hslaValue.addEventListener("input", this.onHslaInputChange);
   },
 
-  async show() {
+  show: Task.async(function* () {
     this.initializeColorWidget();
     this.element.classList.add("colorwidget-show");
 
@@ -399,12 +400,12 @@ ColorWidget.prototype = {
 
     if (this.inspector && this.inspector.selection.nodeFront && this.contrastEnabled) {
       let node = this.inspector.selection.nodeFront;
-      this.closestBackgroundColor = await node.getClosestBackgroundColor();
+      this.closestBackgroundColor = yield node.getClosestBackgroundColor();
     }
     this.updateContrast();
 
     this.updateUI();
-  },
+  }),
 
   onElementClick: function (e) {
     e.stopPropagation();
diff --git a/devtools/client/shared/widgets/FlameGraph.js b/devtools/client/shared/widgets/FlameGraph.js
index 13913f3d647a..60b44ba64e60 100644
--- a/devtools/client/shared/widgets/FlameGraph.js
+++ b/devtools/client/shared/widgets/FlameGraph.js
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 
+const { Task } = require("devtools/shared/task");
 const { ViewHelpers, setNamedTimeout } = require("devtools/client/shared/widgets/view-helpers");
 const { ELLIPSIS } = require("devtools/shared/l10n");
 
@@ -231,8 +232,8 @@ FlameGraph.prototype = {
   /**
    * Destroys this graph.
    */
-  async destroy() {
-    await this.ready();
+  destroy: Task.async(function* () {
+    yield this.ready();
 
     this._window.removeEventListener("keydown", this._onKeyDown);
     this._window.removeEventListener("keyup", this._onKeyUp);
@@ -261,7 +262,7 @@ FlameGraph.prototype = {
     this._data = null;
 
     this.emit("destroyed");
-  },
+  }),
 
   /**
    * Makes sure the canvas graph is of the specified width or height, and
@@ -311,10 +312,10 @@ FlameGraph.prototype = {
    * @return promise
    *         A promise resolved once the data is set.
    */
-  async setDataWhenReady(data) {
-    await this.ready();
+  setDataWhenReady: Task.async(function* (data) {
+    yield this.ready();
     this.setData(data);
-  },
+  }),
 
   /**
    * Gets whether or not this graph has a data source.
diff --git a/devtools/client/shared/widgets/Graphs.js b/devtools/client/shared/widgets/Graphs.js
index b5ccd1a4d73a..b10cec5bebb5 100644
--- a/devtools/client/shared/widgets/Graphs.js
+++ b/devtools/client/shared/widgets/Graphs.js
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 
+const { Task } = require("devtools/shared/task");
 const { setNamedTimeout } = require("devtools/client/shared/widgets/view-helpers");
 const { getCurrentZoom } = require("devtools/shared/layout/utils");
 
@@ -185,8 +186,8 @@ AbstractCanvasGraph.prototype = {
   /**
    * Destroys this graph.
    */
-  async destroy() {
-    await this.ready();
+  destroy: Task.async(function* () {
+    yield this.ready();
 
     this._topWindow.removeEventListener("mousemove", this._onMouseMove);
     this._topWindow.removeEventListener("mouseup", this._onMouseUp);
@@ -220,7 +221,7 @@ AbstractCanvasGraph.prototype = {
     gCachedStripePattern.clear();
 
     this.emit("destroyed");
-  },
+  }),
 
   /**
    * Rendering options. Subclasses should override these.
@@ -296,10 +297,10 @@ AbstractCanvasGraph.prototype = {
    * @return promise
    *         A promise resolved once the data is set.
    */
-  async setDataWhenReady(data) {
-    await this.ready();
+  setDataWhenReady: Task.async(function* (data) {
+    yield this.ready();
     this.setData(data);
-  },
+  }),
 
   /**
    * Adds a mask to this graph.
@@ -1315,12 +1316,12 @@ this.CanvasGraphUtils = {
   /**
    * Merges the animation loop of two graphs.
    */
-  async linkAnimation(graph1, graph2) {
+  linkAnimation: Task.async(function* (graph1, graph2) {
     if (!graph1 || !graph2) {
       return;
     }
-    await graph1.ready();
-    await graph2.ready();
+    yield graph1.ready();
+    yield graph2.ready();
 
     let window = graph1._window;
     window.cancelAnimationFrame(graph1._animationId);
@@ -1333,7 +1334,7 @@ this.CanvasGraphUtils = {
     };
 
     window.requestAnimationFrame(loop);
-  },
+  }),
 
   /**
    * Makes sure selections in one graph are reflected in another.
diff --git a/devtools/client/shared/widgets/LineGraphWidget.js b/devtools/client/shared/widgets/LineGraphWidget.js
index 91422ebb2241..a5622a723d30 100644
--- a/devtools/client/shared/widgets/LineGraphWidget.js
+++ b/devtools/client/shared/widgets/LineGraphWidget.js
@@ -1,5 +1,6 @@
 "use strict";
 
+const { Task } = require("devtools/shared/task");
 const { extend } = require("devtools/shared/extend");
 const { AbstractCanvasGraph, CanvasGraphUtils } = require("devtools/client/shared/widgets/Graphs");
 const { LocalizationHelper } = require("devtools/shared/l10n");
@@ -145,17 +146,17 @@ LineGraphWidget.prototype = extend(AbstractCanvasGraph.prototype, {
    * @param number duration
    *        The duration of the recording in milliseconds.
    */
-  async setDataFromTimestamps(timestamps, interval, duration) {
+  setDataFromTimestamps: Task.async(function* (timestamps, interval, duration) {
     let {
       plottedData,
       plottedMinMaxSum
-    } = await CanvasGraphUtils._performTaskInWorker("plotTimestampsGraph", {
+    } = yield CanvasGraphUtils._performTaskInWorker("plotTimestampsGraph", {
       timestamps, interval, duration
     });
 
     this._tempMinMaxSum = plottedMinMaxSum;
     this.setData(plottedData);
-  },
+  }),
 
   /**
    * Renders the graph's data source.
diff --git a/devtools/client/shared/widgets/VariablesView.jsm b/devtools/client/shared/widgets/VariablesView.jsm
index ccdfa4212db8..167fbd051818 100644
--- a/devtools/client/shared/widgets/VariablesView.jsm
+++ b/devtools/client/shared/widgets/VariablesView.jsm
@@ -24,6 +24,7 @@ const defer = require("devtools/shared/defer");
 const { extend } = require("devtools/shared/extend");
 const { ViewHelpers, setNamedTimeout } =
   require("devtools/client/shared/widgets/view-helpers");
+const { Task } = require("devtools/shared/task");
 const nodeConstants = require("devtools/shared/dom-node-constants");
 const {KeyCodes} = require("devtools/client/shared/keycodes");
 const {PluralForm} = require("devtools/shared/plural-form");
@@ -2775,23 +2776,23 @@ Variable.prototype = extend(Scope.prototype, {
 
     event && event.stopPropagation();
 
-    return (async function () {
-      await this.toolbox.initInspector();
+    return Task.spawn(function* () {
+      yield this.toolbox.initInspector();
 
       let nodeFront = this._nodeFront;
       if (!nodeFront) {
-        nodeFront = await this.toolbox.walker.getNodeActorFromObjectActor(this._valueGrip.actor);
+        nodeFront = yield this.toolbox.walker.getNodeActorFromObjectActor(this._valueGrip.actor);
       }
 
       if (nodeFront) {
-        await this.toolbox.selectTool("inspector");
+        yield this.toolbox.selectTool("inspector");
 
         let inspectorReady = defer();
         this.toolbox.getPanel("inspector").once("inspector-updated", inspectorReady.resolve);
-        await this.toolbox.selection.setNodeFront(nodeFront, "variables-view");
-        await inspectorReady.promise;
+        yield this.toolbox.selection.setNodeFront(nodeFront, "variables-view");
+        yield inspectorReady.promise;
       }
-    }.bind(this))();
+    }.bind(this));
   },
 
   /**
diff --git a/devtools/client/shared/widgets/tooltip/HTMLTooltip.js b/devtools/client/shared/widgets/tooltip/HTMLTooltip.js
index 6c1ea90c8313..f607c1db69dc 100644
--- a/devtools/client/shared/widgets/tooltip/HTMLTooltip.js
+++ b/devtools/client/shared/widgets/tooltip/HTMLTooltip.js
@@ -9,6 +9,7 @@
 const EventEmitter = require("devtools/shared/event-emitter");
 const {TooltipToggle} = require("devtools/client/shared/widgets/tooltip/TooltipToggle");
 const {listenOnce} = require("devtools/shared/async-utils");
+const {Task} = require("devtools/shared/task");
 
 const XUL_NS = "http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul";
 const XHTML_NS = "http://www.w3.org/1999/xhtml";
@@ -323,7 +324,7 @@ HTMLTooltip.prototype = {
    *        - {Number} x: optional, horizontal offset between the anchor and the tooltip
    *        - {Number} y: optional, vertical offset between the anchor and the tooltip
    */
-  async show(anchor, {position, x = 0, y = 0} = {}) {
+  show: Task.async(function* (anchor, {position, x = 0, y = 0} = {}) {
     // Get anchor geometry
     let anchorRect = getRelativeRect(anchor, this.doc);
     if (this.useXulWrapper) {
@@ -372,7 +373,7 @@ HTMLTooltip.prototype = {
     }
 
     if (this.useXulWrapper) {
-      await this._showXulWrapperAt(left, top);
+      yield this._showXulWrapperAt(left, top);
     } else {
       this.container.style.left = left + "px";
       this.container.style.top = top + "px";
@@ -391,7 +392,7 @@ HTMLTooltip.prototype = {
       this.topWindow.addEventListener("click", this._onClick, true);
       this.emit("shown");
     }, 0);
-  },
+  }),
 
   /**
    * Calculate the rect of the viewport that limits the tooltip dimensions. When using a
@@ -445,7 +446,7 @@ HTMLTooltip.prototype = {
    * Hide the current tooltip. The event "hidden" will be fired when the tooltip
    * is hidden.
    */
-  async hide() {
+  hide: Task.async(function* () {
     this.doc.defaultView.clearTimeout(this.attachEventsTimer);
     if (!this.isVisible()) {
       this.emit("hidden");
@@ -455,7 +456,7 @@ HTMLTooltip.prototype = {
     this.topWindow.removeEventListener("click", this._onClick, true);
     this.container.classList.remove("tooltip-visible");
     if (this.useXulWrapper) {
-      await this._hideXulWrapper();
+      yield this._hideXulWrapper();
     }
 
     this.emit("hidden");
@@ -465,7 +466,7 @@ HTMLTooltip.prototype = {
       this._focusedElement.focus();
       this._focusedElement = null;
     }
-  },
+  }),
 
   /**
    * Check if the tooltip is currently displayed.
diff --git a/devtools/client/shared/widgets/tooltip/TooltipToggle.js b/devtools/client/shared/widgets/tooltip/TooltipToggle.js
index 80f5e8b14471..11a4f68e775d 100644
--- a/devtools/client/shared/widgets/tooltip/TooltipToggle.js
+++ b/devtools/client/shared/widgets/tooltip/TooltipToggle.js
@@ -6,6 +6,8 @@
 
 "use strict";
 
+const {Task} = require("devtools/shared/task");
+
 const DEFAULT_TOGGLE_DELAY = 50;
 
 /**
@@ -142,14 +144,14 @@ TooltipToggle.prototype = {
    * @return {Promise} a promise that will resolve the anchor to use for the
    *         tooltip or null if no valid target was found.
    */
-  async isValidHoverTarget(target) {
-    let res = await this._targetNodeCb(target, this.tooltip);
+  isValidHoverTarget: Task.async(function* (target) {
+    let res = yield this._targetNodeCb(target, this.tooltip);
     if (res) {
       return res.nodeName ? res : target;
     }
 
     return null;
-  },
+  }),
 
   _onMouseOut: function (event) {
     // Only hide the tooltip if the mouse leaves baseNode.
diff --git a/devtools/client/sourceeditor/test/browser_editor_autocomplete_events.js b/devtools/client/sourceeditor/test/browser_editor_autocomplete_events.js
index c0a1aa3463b7..509014a0df66 100644
--- a/devtools/client/sourceeditor/test/browser_editor_autocomplete_events.js
+++ b/devtools/client/sourceeditor/test/browser_editor_autocomplete_events.js
@@ -8,30 +8,30 @@ const {InspectorFront} = require("devtools/shared/fronts/inspector");
 const TEST_URI = "data:text/html;charset=UTF-8,<html><body><bar></bar>" +
                  "<div id='baz'></div><body></html>";
 
-add_task(async function () {
-  await addTab(TEST_URI);
-  await runTests();
+add_task(function* () {
+  yield addTab(TEST_URI);
+  yield runTests();
 });
 
-async function runTests() {
+function* runTests() {
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  await target.makeRemote();
+  yield target.makeRemote();
   let inspector = InspectorFront(target.client, target.form);
-  let walker = await inspector.getWalker();
-  let {ed, win, edWin} = await setup(null, {
+  let walker = yield inspector.getWalker();
+  let {ed, win, edWin} = yield setup(null, {
     autocomplete: true,
     mode: Editor.modes.css,
     autocompleteOpts: {walker: walker, cssProperties: getClientCssProperties()}
   });
-  await testMouse(ed, edWin);
-  await testKeyboard(ed, edWin);
-  await testKeyboardCycle(ed, edWin);
-  await testKeyboardCycleForPrefixedString(ed, edWin);
-  await testKeyboardCSSComma(ed, edWin);
+  yield testMouse(ed, edWin);
+  yield testKeyboard(ed, edWin);
+  yield testKeyboardCycle(ed, edWin);
+  yield testKeyboardCycleForPrefixedString(ed, edWin);
+  yield testKeyboardCSSComma(ed, edWin);
   teardown(ed, win);
 }
 
-async function testKeyboard(ed, win) {
+function* testKeyboard(ed, win) {
   ed.focus();
   ed.setText("b");
   ed.setCursor({line: 1, ch: 1});
@@ -43,13 +43,13 @@ async function testKeyboard(ed, win) {
   EventUtils.synthesizeKey("VK_" + autocompleteKey, { ctrlKey: true }, win);
 
   info("Waiting for popup to be opened");
-  await popupOpened;
+  yield popupOpened;
 
   EventUtils.synthesizeKey("VK_RETURN", { }, win);
   is(ed.getText(), "bar", "Editor text has been updated");
 }
 
-async function testKeyboardCycle(ed, win) {
+function* testKeyboardCycle(ed, win) {
   ed.focus();
   ed.setText("b");
   ed.setCursor({line: 1, ch: 1});
@@ -61,7 +61,7 @@ async function testKeyboardCycle(ed, win) {
   EventUtils.synthesizeKey("VK_" + autocompleteKey, { ctrlKey: true }, win);
 
   info("Waiting for popup to be opened");
-  await popupOpened;
+  yield popupOpened;
 
   EventUtils.synthesizeKey("VK_DOWN", { }, win);
   is(ed.getText(), "bar", "Editor text has been updated");
@@ -73,7 +73,7 @@ async function testKeyboardCycle(ed, win) {
   is(ed.getText(), "#baz", "Editor text has been updated");
 }
 
-async function testKeyboardCycleForPrefixedString(ed, win) {
+function* testKeyboardCycleForPrefixedString(ed, win) {
   ed.focus();
   ed.setText("#b");
   ed.setCursor({line: 1, ch: 2});
@@ -85,13 +85,13 @@ async function testKeyboardCycleForPrefixedString(ed, win) {
   EventUtils.synthesizeKey("VK_" + autocompleteKey, { ctrlKey: true }, win);
 
   info("Waiting for popup to be opened");
-  await popupOpened;
+  yield popupOpened;
 
   EventUtils.synthesizeKey("VK_DOWN", { }, win);
   is(ed.getText(), "#baz", "Editor text has been updated");
 }
 
-async function testKeyboardCSSComma(ed, win) {
+function* testKeyboardCSSComma(ed, win) {
   ed.focus();
   ed.setText("b");
   ed.setCursor({line: 1, ch: 1});
@@ -104,12 +104,12 @@ async function testKeyboardCSSComma(ed, win) {
 
   EventUtils.synthesizeKey(",", { }, win);
 
-  await wait(500);
+  yield wait(500);
 
   ok(!isPopupOpened, "Autocompletion shouldn't be opened");
 }
 
-async function testMouse(ed, win) {
+function* testMouse(ed, win) {
   ed.focus();
   ed.setText("b");
   ed.setCursor({line: 1, ch: 1});
@@ -121,7 +121,7 @@ async function testMouse(ed, win) {
   EventUtils.synthesizeKey("VK_" + autocompleteKey, { ctrlKey: true }, win);
 
   info("Waiting for popup to be opened");
-  await popupOpened;
+  yield popupOpened;
   ed.getAutocompletionPopup()._list.children[2].click();
   is(ed.getText(), "#baz", "Editor text has been updated");
 }
diff --git a/devtools/client/sourceeditor/test/browser_editor_find_again.js b/devtools/client/sourceeditor/test/browser_editor_find_again.js
index 147f39702c92..47f0e19c2a7d 100644
--- a/devtools/client/sourceeditor/test/browser_editor_find_again.js
+++ b/devtools/client/sourceeditor/test/browser_editor_find_again.js
@@ -70,7 +70,7 @@ function testFindAgain(ed, inputLine, expectCursor, isFindPrev = false) {
     "find: " + inputLine + " expects cursor: " + expectCursor.toSource());
 }
 
-const testSearchBoxTextIsSelected = async function (ed) {
+const testSearchBoxTextIsSelected = Task.async(function* (ed) {
   let edDoc = ed.container.contentDocument;
   let edWin = edDoc.defaultView;
 
@@ -93,7 +93,7 @@ const testSearchBoxTextIsSelected = async function (ed) {
   input = edDoc.querySelector("input[type=search]");
   ok(input, "find command key opens the search box");
 
-  await dispatchAndWaitForFocus(input);
+  yield dispatchAndWaitForFocus(input);
 
   let { selectionStart, selectionEnd, value } = input;
 
@@ -112,9 +112,9 @@ const testSearchBoxTextIsSelected = async function (ed) {
 
   // Close search box
   EventUtils.synthesizeKey("VK_ESCAPE", {}, edWin);
-};
+});
 
-const testReplaceBoxTextIsSelected = async function (ed) {
+const testReplaceBoxTextIsSelected = Task.async(function* (ed) {
   let edDoc = ed.container.contentDocument;
   let edWin = edDoc.defaultView;
 
@@ -135,7 +135,7 @@ const testReplaceBoxTextIsSelected = async function (ed) {
   // it seems that during the tests can be lost
   input.focus();
 
-  await dispatchAndWaitForFocus(input);
+  yield dispatchAndWaitForFocus(input);
 
   let { selectionStart, selectionEnd, value } = input;
 
@@ -151,10 +151,10 @@ const testReplaceBoxTextIsSelected = async function (ed) {
 
   // Close dialog box
   EventUtils.synthesizeKey("VK_ESCAPE", {}, edWin);
-};
+});
 
-add_task(async function () {
-  let { ed, win } = await setup();
+add_task(function* () {
+  let { ed, win } = yield setup();
 
   ed.setText([
     "// line 1",
@@ -164,7 +164,7 @@ add_task(async function () {
     "//     line 5"
   ].join("\n"));
 
-  await promiseWaitForFocus();
+  yield promiseWaitForFocus();
 
   openSearchBox(ed);
 
@@ -204,12 +204,12 @@ add_task(async function () {
   ];
 
   for (let v of testVectors) {
-    await testFindAgain(ed, ...v);
+    yield testFindAgain(ed, ...v);
   }
 
-  await testSearchBoxTextIsSelected(ed);
+  yield testSearchBoxTextIsSelected(ed);
 
-  await testReplaceBoxTextIsSelected(ed);
+  yield testReplaceBoxTextIsSelected(ed);
 
   teardown(ed, win);
 });
diff --git a/devtools/client/sourceeditor/test/browser_editor_script_injection.js b/devtools/client/sourceeditor/test/browser_editor_script_injection.js
index 8a4c368196ec..05487b4f21eb 100644
--- a/devtools/client/sourceeditor/test/browser_editor_script_injection.js
+++ b/devtools/client/sourceeditor/test/browser_editor_script_injection.js
@@ -6,16 +6,16 @@
 
 "use strict";
 
-add_task(async function () {
-  await runTest();
+add_task(function* () {
+  yield runTest();
 });
 
-async function runTest() {
+function* runTest() {
   const baseURL =
     "chrome://mochitests/content/browser/devtools/client/sourceeditor/test";
   const injectedText = "Script successfully injected!";
 
-  let {ed, win} = await setup(null, {
+  let {ed, win} = yield setup(null, {
     mode: "ruby",
     externalScripts: [`${baseURL}/cm_script_injection_test.js`,
                       `${baseURL}/cm_mode_ruby.js`]
diff --git a/devtools/client/storage/test/browser_storage_basic.js b/devtools/client/storage/test/browser_storage_basic.js
index 254fdc3b4a8f..0a309bb4edc9 100644
--- a/devtools/client/storage/test/browser_storage_basic.js
+++ b/devtools/client/storage/test/browser_storage_basic.js
@@ -102,7 +102,7 @@ function testTree() {
 /**
  * Test that correct table entries are shown for each of the tree item
  */
-async function testTables() {
+function* testTables() {
   let doc = gPanelWindow.document;
   // Expand all nodes so that the synthesized click event actually works
   gUI.tree.expandAll();
@@ -115,7 +115,7 @@ async function testTables() {
 
   // Click rest of the tree items and wait for the table to be updated
   for (let [treeItem, items] of testCases.slice(1)) {
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     // Check whether correct number of items are present in the table
     is(doc.querySelectorAll(
@@ -130,11 +130,11 @@ async function testTables() {
   }
 }
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   testTree();
-  await testTables();
+  yield testTables();
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_basic_usercontextid_1.js b/devtools/client/storage/test/browser_storage_basic_usercontextid_1.js
index e07a164fa549..06dff6360cd7 100644
--- a/devtools/client/storage/test/browser_storage_basic_usercontextid_1.js
+++ b/devtools/client/storage/test/browser_storage_basic_usercontextid_1.js
@@ -87,7 +87,7 @@ function testTree(tests) {
 /**
  * Test that correct table entries are shown for each of the tree item
  */
-async function testTables(tests) {
+function* testTables(tests) {
   let doc = gPanelWindow.document;
   // Expand all nodes so that the synthesized click event actually works
   gUI.tree.expandAll();
@@ -100,7 +100,7 @@ async function testTables(tests) {
 
   // Click rest of the tree items and wait for the table to be updated
   for (let [treeItem, items] of tests.slice(1)) {
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     // Check whether correct number of items are present in the table
     is(doc.querySelectorAll(
@@ -115,11 +115,11 @@ async function testTables(tests) {
   }
 }
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   testTree(testCases);
-  await testTables(testCases);
+  yield testTables(testCases);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_basic_usercontextid_2.js b/devtools/client/storage/test/browser_storage_basic_usercontextid_2.js
index c4eb0bfdafdc..80a7b937b34e 100644
--- a/devtools/client/storage/test/browser_storage_basic_usercontextid_2.js
+++ b/devtools/client/storage/test/browser_storage_basic_usercontextid_2.js
@@ -81,7 +81,7 @@ function testTree(tests) {
 /**
  * Test that correct table entries are shown for each of the tree item
  */
-async function testTables(tests) {
+function* testTables(tests) {
   let doc = gPanelWindow.document;
   // Expand all nodes so that the synthesized click event actually works
   gUI.tree.expandAll();
@@ -94,7 +94,7 @@ async function testTables(tests) {
 
   // Click rest of the tree items and wait for the table to be updated
   for (let [treeItem, items] of tests.slice(1)) {
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     // Check whether correct number of items are present in the table
     is(doc.querySelectorAll(
@@ -109,12 +109,12 @@ async function testTables(tests) {
   }
 }
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings-usercontextid.html",
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings-usercontextid.html",
                                {userContextId: 1});
 
   testTree(testCasesUserContextId);
-  await testTables(testCasesUserContextId);
+  yield testTables(testCasesUserContextId);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_basic_with_fragment.js b/devtools/client/storage/test/browser_storage_basic_with_fragment.js
index e012ef82abf6..2353b4384711 100644
--- a/devtools/client/storage/test/browser_storage_basic_with_fragment.js
+++ b/devtools/client/storage/test/browser_storage_basic_with_fragment.js
@@ -105,7 +105,7 @@ function testTree() {
 /**
  * Test that correct table entries are shown for each of the tree item
  */
-async function testTables() {
+function* testTables() {
   let doc = gPanelWindow.document;
   // Expand all nodes so that the synthesized click event actually works
   gUI.tree.expandAll();
@@ -118,7 +118,7 @@ async function testTables() {
 
   // Click rest of the tree items and wait for the table to be updated
   for (let [treeItem, items] of testCases.slice(1)) {
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     // Check whether correct number of items are present in the table
     is(doc.querySelectorAll(
@@ -133,12 +133,12 @@ async function testTables() {
   }
 }
 
-add_task(async function () {
-  await openTabAndSetupStorage(
+add_task(function* () {
+  yield openTabAndSetupStorage(
     MAIN_DOMAIN + "storage-listings-with-fragment.html#abc");
 
   testTree();
-  await testTables();
+  yield testTables();
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cache_delete.js b/devtools/client/storage/test/browser_storage_cache_delete.js
index 0577582f3376..fe99d28bcdd3 100644
--- a/devtools/client/storage/test/browser_storage_cache_delete.js
+++ b/devtools/client/storage/test/browser_storage_cache_delete.js
@@ -8,8 +8,8 @@
 
 // Test deleting a Cache object from the tree using context menu
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   let contextMenu = gPanelWindow.document.getElementById("storage-tree-popup");
   let menuDeleteItem = contextMenu.querySelector("#storage-tree-popup-delete");
@@ -17,7 +17,7 @@ add_task(async function () {
   let cacheToDelete = ["Cache", "http://test1.example.org", "plop"];
 
   info("test state before delete");
-  await selectTreeItem(cacheToDelete);
+  yield selectTreeItem(cacheToDelete);
   ok(gUI.tree.isSelected(cacheToDelete), "Cache item is present in the tree");
 
   info("do the delete");
@@ -27,7 +27,7 @@ add_task(async function () {
   let target = gPanelWindow.document.querySelector(selector);
   ok(target, "Cache item's tree element is present");
 
-  await waitForContextMenu(contextMenu, target, () => {
+  yield waitForContextMenu(contextMenu, target, () => {
     info("Opened tree context menu");
     menuDeleteItem.click();
 
@@ -36,11 +36,11 @@ add_task(async function () {
       `Context menu item label contains '${cacheName}')`);
   });
 
-  await eventWait;
+  yield eventWait;
 
   info("test state after delete");
-  await selectTreeItem(cacheToDelete);
+  yield selectTreeItem(cacheToDelete);
   ok(!gUI.tree.isSelected(cacheToDelete), "Cache item is no longer present in the tree");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cache_error.js b/devtools/client/storage/test/browser_storage_cache_error.js
index 04310dba5d53..dfc6056a704a 100644
--- a/devtools/client/storage/test/browser_storage_cache_error.js
+++ b/devtools/client/storage/test/browser_storage_cache_error.js
@@ -6,14 +6,14 @@
 
 // Test handling errors in CacheStorage
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cache-error.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cache-error.html");
 
   const cacheItemId = ["Cache", "javascript:parent.frameContent"];
 
-  await selectTreeItem(cacheItemId);
+  yield selectTreeItem(cacheItemId);
   ok(gUI.tree.isSelected(cacheItemId),
     `The item ${cacheItemId.join(" > ")} is present in the tree`);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_add.js b/devtools/client/storage/test/browser_storage_cookies_add.js
index 1fca43b3b064..ac66eb92cbf1 100644
--- a/devtools/client/storage/test/browser_storage_cookies_add.js
+++ b/devtools/client/storage/test/browser_storage_cookies_add.js
@@ -6,15 +6,15 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
   showAllColumns(true);
 
-  await performAdd(["cookies", "http://test1.example.org"]);
-  await performAdd(["cookies", "http://test1.example.org"]);
-  await performAdd(["cookies", "http://test1.example.org"]);
-  await performAdd(["cookies", "http://test1.example.org"]);
-  await performAdd(["cookies", "http://test1.example.org"]);
+  yield performAdd(["cookies", "http://test1.example.org"]);
+  yield performAdd(["cookies", "http://test1.example.org"]);
+  yield performAdd(["cookies", "http://test1.example.org"]);
+  yield performAdd(["cookies", "http://test1.example.org"]);
+  yield performAdd(["cookies", "http://test1.example.org"]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_delete_all.js b/devtools/client/storage/test/browser_storage_cookies_delete_all.js
index 2df30f768bef..b8c0418f895d 100644
--- a/devtools/client/storage/test/browser_storage_cookies_delete_all.js
+++ b/devtools/client/storage/test/browser_storage_cookies_delete_all.js
@@ -8,7 +8,7 @@
 
 // Test deleting all cookies
 
-async function performDelete(store, rowName, action) {
+function* performDelete(store, rowName, action) {
   let contextMenu = gPanelWindow.document.getElementById(
     "storage-table-popup");
   let menuDeleteAllItem = contextMenu.querySelector(
@@ -20,12 +20,12 @@ async function performDelete(store, rowName, action) {
 
   let storeName = store.join(" > ");
 
-  await selectTreeItem(store);
+  yield selectTreeItem(store);
 
   let eventWait = gUI.once("store-objects-updated");
   let cells = getRowCells(rowName, true);
 
-  await waitForContextMenu(contextMenu, cells.name, () => {
+  yield waitForContextMenu(contextMenu, cells.name, () => {
     info(`Opened context menu in ${storeName}, row '${rowName}'`);
     switch (action) {
       case "deleteAll":
@@ -43,14 +43,14 @@ async function performDelete(store, rowName, action) {
     }
   });
 
-  await eventWait;
+  yield eventWait;
 }
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   info("test state before delete");
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"], [
         getCookieId("c1", "test1.example.org", "/browser"),
@@ -78,10 +78,10 @@ add_task(async function () {
   info("delete all from domain");
   // delete only cookies that match the host exactly
   let id = getCookieId("c1", "test1.example.org", "/browser");
-  await performDelete(["cookies", "http://test1.example.org"], id, "deleteAllFrom");
+  yield performDelete(["cookies", "http://test1.example.org"], id, "deleteAllFrom");
 
   info("test state after delete all from domain");
-  await checkState([
+  yield checkState([
     // Domain cookies (.example.org) must not be deleted.
     [
       ["cookies", "http://test1.example.org"],
@@ -110,11 +110,11 @@ add_task(async function () {
   info("delete all session cookies");
   // delete only session cookies
   id = getCookieId("cs2", ".example.org", "/");
-  await performDelete(["cookies", "http://sectest1.example.org"], id,
+  yield performDelete(["cookies", "http://sectest1.example.org"], id,
     "deleteAllSessionCookies");
 
   info("test state after delete all session cookies");
-  await checkState([
+  yield checkState([
     // Cookies with expiry date must not be deleted.
     [
       ["cookies", "http://test1.example.org"],
@@ -137,15 +137,15 @@ add_task(async function () {
   info("delete all");
   // delete all cookies for host, including domain cookies
   id = getCookieId("uc2", ".example.org", "/");
-  await performDelete(["cookies", "http://sectest1.example.org"], id, "deleteAll");
+  yield performDelete(["cookies", "http://sectest1.example.org"], id, "deleteAll");
 
   info("test state after delete all");
-  await checkState([
+  yield checkState([
     // Domain cookies (.example.org) are deleted too, so deleting in sectest1
     // also removes stuff from test1.
     [["cookies", "http://test1.example.org"], []],
     [["cookies", "https://sectest1.example.org"], []],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_domain.js b/devtools/client/storage/test/browser_storage_cookies_domain.js
index 369df8a73727..e78756471249 100644
--- a/devtools/client/storage/test/browser_storage_cookies_domain.js
+++ b/devtools/client/storage/test/browser_storage_cookies_domain.js
@@ -9,10 +9,10 @@
 // Test that cookies with domain equal to full host name are listed.
 // E.g., ".example.org" vs. example.org). Bug 1149497.
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -25,5 +25,5 @@ add_task(async function () {
     ],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_domain_port.js b/devtools/client/storage/test/browser_storage_cookies_domain_port.js
index 05091657cc40..55fcb571894c 100644
--- a/devtools/client/storage/test/browser_storage_cookies_domain_port.js
+++ b/devtools/client/storage/test/browser_storage_cookies_domain_port.js
@@ -9,10 +9,10 @@
 // Test that cookies with domain equal to full host name and port are listed.
 // E.g., ".example.org:8000" vs. example.org:8000).
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN_WITH_PORT + "storage-cookies.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN_WITH_PORT + "storage-cookies.html");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org:8000"],
       [
@@ -25,5 +25,5 @@ add_task(async function () {
     ],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_edit.js b/devtools/client/storage/test/browser_storage_cookies_edit.js
index 12a2899ecdb0..14944b398522 100644
--- a/devtools/client/storage/test/browser_storage_cookies_edit.js
+++ b/devtools/client/storage/test/browser_storage_cookies_edit.js
@@ -6,24 +6,24 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
   showAllColumns(true);
 
   let id = getCookieId("test3", ".test1.example.org", "/browser");
-  await editCell(id, "name", "newTest3");
+  yield editCell(id, "name", "newTest3");
 
   id = getCookieId("newTest3", ".test1.example.org", "/browser");
-  await editCell(id, "host", "test1.example.org");
+  yield editCell(id, "host", "test1.example.org");
 
   id = getCookieId("newTest3", "test1.example.org", "/browser");
-  await editCell(id, "path", "/");
+  yield editCell(id, "path", "/");
 
   id = getCookieId("newTest3", "test1.example.org", "/");
-  await editCell(id, "expires", "Tue, 14 Feb 2040 17:41:14 GMT");
-  await editCell(id, "value", "newValue3");
-  await editCell(id, "isSecure", "true");
-  await editCell(id, "isHttpOnly", "true");
+  yield editCell(id, "expires", "Tue, 14 Feb 2040 17:41:14 GMT");
+  yield editCell(id, "value", "newValue3");
+  yield editCell(id, "isSecure", "true");
+  yield editCell(id, "isHttpOnly", "true");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_edit_keyboard.js b/devtools/client/storage/test/browser_storage_cookies_edit_keyboard.js
index 5f185d7964ee..4d1f3b3aaba2 100644
--- a/devtools/client/storage/test/browser_storage_cookies_edit_keyboard.js
+++ b/devtools/client/storage/test/browser_storage_cookies_edit_keyboard.js
@@ -6,20 +6,20 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
   showAllColumns(true);
   showColumn("uniqueKey", false);
 
   let id = getCookieId("test4", "test1.example.org", "/browser");
-  await startCellEdit(id, "name");
-  await typeWithTerminator("test6", "KEY_Tab");
-  await typeWithTerminator(".example.org", "KEY_Tab");
-  await typeWithTerminator("/", "KEY_Tab");
-  await typeWithTerminator("Tue, 25 Dec 2040 12:00:00 GMT", "KEY_Tab");
-  await typeWithTerminator("test6value", "KEY_Tab");
-  await typeWithTerminator("false", "KEY_Tab");
-  await typeWithTerminator("false", "KEY_Tab");
+  yield startCellEdit(id, "name");
+  yield typeWithTerminator("test6", "KEY_Tab");
+  yield typeWithTerminator(".example.org", "KEY_Tab");
+  yield typeWithTerminator("/", "KEY_Tab");
+  yield typeWithTerminator("Tue, 25 Dec 2040 12:00:00 GMT", "KEY_Tab");
+  yield typeWithTerminator("test6value", "KEY_Tab");
+  yield typeWithTerminator("false", "KEY_Tab");
+  yield typeWithTerminator("false", "KEY_Tab");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_samesite.js b/devtools/client/storage/test/browser_storage_cookies_samesite.js
index 1417072487ba..bde7be1607f5 100644
--- a/devtools/client/storage/test/browser_storage_cookies_samesite.js
+++ b/devtools/client/storage/test/browser_storage_cookies_samesite.js
@@ -8,8 +8,8 @@
 
 // Test that the samesite cookie attribute is displayed correctly.
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies-samesite.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies-samesite.html");
 
   let id1 = getCookieId("test1", "test1.example.org",
                         "/browser/devtools/client/storage/test/");
@@ -18,7 +18,7 @@ add_task(async function () {
   let id3 = getCookieId("test3", "test1.example.org",
                         "/browser/devtools/client/storage/test/");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [ id1, id2, id3 ]
@@ -33,5 +33,5 @@ add_task(async function () {
   is(sameSite2, "Lax", `sameSite2 is "Lax"`);
   is(sameSite3, "Strict", `sameSite3 is "Strict"`);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_cookies_tab_navigation.js b/devtools/client/storage/test/browser_storage_cookies_tab_navigation.js
index 5e320ca97ac4..5da359b8d643 100644
--- a/devtools/client/storage/test/browser_storage_cookies_tab_navigation.js
+++ b/devtools/client/storage/test/browser_storage_cookies_tab_navigation.js
@@ -6,12 +6,12 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-cookies.html");
   showAllColumns(true);
 
   let id = getCookieId("test1", ".test1.example.org", "/browser");
-  await startCellEdit(id, "name");
+  yield startCellEdit(id, "name");
 
   PressKeyXTimes("VK_TAB", 18);
   is(getCurrentEditorValue(), "value3",
@@ -21,5 +21,5 @@ add_task(async function () {
   is(getCurrentEditorValue(), "test1",
      "We have shift-tabbed to the correct cell.");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_delete.js b/devtools/client/storage/test/browser_storage_delete.js
index b0d46046080d..f154c6a6827c 100644
--- a/devtools/client/storage/test/browser_storage_delete.js
+++ b/devtools/client/storage/test/browser_storage_delete.js
@@ -23,8 +23,8 @@ const TEST_CASES = [
    MAIN_DOMAIN + "404_cached_file.js", "url"],
 ];
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   let contextMenu = gPanelWindow.document.getElementById("storage-table-popup");
   let menuDeleteItem = contextMenu.querySelector("#storage-table-popup-delete");
@@ -33,14 +33,14 @@ add_task(async function () {
     let treeItemName = treeItem.join(" > ");
 
     info(`Selecting tree item ${treeItemName}`);
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     let row = getRowCells(rowName);
     ok(gUI.table.items.has(rowName), `There is a row '${rowName}' in ${treeItemName}`);
 
     let eventWait = gUI.once("store-objects-updated");
 
-    await waitForContextMenu(contextMenu, row[cellToClick], () => {
+    yield waitForContextMenu(contextMenu, row[cellToClick], () => {
       info(`Opened context menu in ${treeItemName}, row '${rowName}'`);
       menuDeleteItem.click();
       let truncatedRowName = String(rowName).replace(SEPARATOR_GUID, "-").substr(0, 16);
@@ -48,11 +48,11 @@ add_task(async function () {
         `Context menu item label contains '${rowName}' (maybe truncated)`);
     });
 
-    await eventWait;
+    yield eventWait;
 
     ok(!gUI.table.items.has(rowName),
       `There is no row '${rowName}' in ${treeItemName} after deletion`);
   }
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_delete_all.js b/devtools/client/storage/test/browser_storage_delete_all.js
index c427266cee82..9fd6b3f01fa2 100644
--- a/devtools/client/storage/test/browser_storage_delete_all.js
+++ b/devtools/client/storage/test/browser_storage_delete_all.js
@@ -8,8 +8,8 @@
 
 // Test deleting all storage items
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   let contextMenu = gPanelWindow.document.getElementById("storage-table-popup");
   let menuDeleteAllItem = contextMenu.querySelector(
@@ -35,7 +35,7 @@ add_task(async function () {
       [MAIN_DOMAIN + "404_cached_file.js", MAIN_DOMAIN + "browser_storage_basic.js"]],
   ];
 
-  await checkState(beforeState);
+  yield checkState(beforeState);
 
   info("do the delete");
   const deleteHosts = [
@@ -49,17 +49,17 @@ add_task(async function () {
   for (let [store, rowName, cellToClick] of deleteHosts) {
     let storeName = store.join(" > ");
 
-    await selectTreeItem(store);
+    yield selectTreeItem(store);
 
     let eventWait = gUI.once("store-objects-cleared");
 
     let cell = getRowCells(rowName)[cellToClick];
-    await waitForContextMenu(contextMenu, cell, () => {
+    yield waitForContextMenu(contextMenu, cell, () => {
       info(`Opened context menu in ${storeName}, row '${rowName}'`);
       menuDeleteAllItem.click();
     });
 
-    await eventWait;
+    yield eventWait;
   }
 
   info("test state after delete");
@@ -84,7 +84,7 @@ add_task(async function () {
       []],
   ];
 
-  await checkState(afterState);
+  yield checkState(afterState);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_delete_tree.js b/devtools/client/storage/test/browser_storage_delete_tree.js
index a7570a211544..32fd410a0d84 100644
--- a/devtools/client/storage/test/browser_storage_delete_tree.js
+++ b/devtools/client/storage/test/browser_storage_delete_tree.js
@@ -8,15 +8,15 @@
 
 // Test deleting all storage items from the tree.
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   let contextMenu = gPanelWindow.document.getElementById("storage-tree-popup");
   let menuDeleteAllItem = contextMenu.querySelector(
     "#storage-tree-popup-delete-all");
 
   info("test state before delete");
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -47,7 +47,7 @@ add_task(async function () {
   for (let store of deleteHosts) {
     let storeName = store.join(" > ");
 
-    await selectTreeItem(store);
+    yield selectTreeItem(store);
 
     let eventName = "store-objects-" +
       (store[0] == "cookies" ? "updated" : "cleared");
@@ -56,16 +56,16 @@ add_task(async function () {
     let selector = `[data-id='${JSON.stringify(store)}'] > .tree-widget-item`;
     let target = gPanelWindow.document.querySelector(selector);
     ok(target, `tree item found in ${storeName}`);
-    await waitForContextMenu(contextMenu, target, () => {
+    yield waitForContextMenu(contextMenu, target, () => {
       info(`Opened tree context menu in ${storeName}`);
       menuDeleteAllItem.click();
     });
 
-    await eventWait;
+    yield eventWait;
   }
 
   info("test state after delete");
-  await checkState([
+  yield checkState([
     [["cookies", "http://test1.example.org"], []],
     [["localStorage", "http://test1.example.org"], []],
     [["sessionStorage", "http://test1.example.org"], []],
@@ -73,5 +73,5 @@ add_task(async function () {
     [["Cache", "http://test1.example.org", "plop"], []],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_delete_usercontextid.js b/devtools/client/storage/test/browser_storage_delete_usercontextid.js
index 988fda8945f9..c9b84771b51d 100644
--- a/devtools/client/storage/test/browser_storage_delete_usercontextid.js
+++ b/devtools/client/storage/test/browser_storage_delete_usercontextid.js
@@ -105,7 +105,7 @@ function testTree(tests) {
 /**
  * Test that correct table entries are shown for each of the tree item
  */
-async function testTables(tests) {
+function* testTables(tests) {
   let doc = gPanelWindow.document;
   // Expand all nodes so that the synthesized click event actually works
   gUI.tree.expandAll();
@@ -118,7 +118,7 @@ async function testTables(tests) {
 
   // Click rest of the tree items and wait for the table to be updated
   for (let [treeItem, items] of tests.slice(1)) {
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     // Check whether correct number of items are present in the table
     is(doc.querySelectorAll(
@@ -133,14 +133,14 @@ async function testTables(tests) {
   }
 }
 
-add_task(async function () {
+add_task(function* () {
   // First, open a tab with the default userContextId and setup its storages.
-  let tabDefault = await openTab(MAIN_DOMAIN + "storage-listings.html");
+  let tabDefault = yield openTab(MAIN_DOMAIN + "storage-listings.html");
 
   // Second, start testing for userContextId 1.
   // We use the same item name as the default page has to see deleting items
   // from userContextId 1 will affect default one or not.
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html", {userContextId: 1});
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html", {userContextId: 1});
 
   let contextMenu = gPanelWindow.document.getElementById("storage-table-popup");
   let menuDeleteItem = contextMenu.querySelector("#storage-table-popup-delete");
@@ -149,14 +149,14 @@ add_task(async function () {
     let treeItemName = treeItem.join(" > ");
 
     info(`Selecting tree item ${treeItemName}`);
-    await selectTreeItem(treeItem);
+    yield selectTreeItem(treeItem);
 
     let row = getRowCells(rowName);
     ok(gUI.table.items.has(rowName), `There is a row '${rowName}' in ${treeItemName}`);
 
     let eventWait = gUI.once("store-objects-updated");
 
-    await waitForContextMenu(contextMenu, row[cellToClick], () => {
+    yield waitForContextMenu(contextMenu, row[cellToClick], () => {
       info(`Opened context menu in ${treeItemName}, row '${rowName}'`);
       menuDeleteItem.click();
       let truncatedRowName = String(rowName).replace(SEPARATOR_GUID, "-").substr(0, 16);
@@ -164,18 +164,18 @@ add_task(async function () {
         `Context menu item label contains '${rowName}' (maybe truncated)`);
     });
 
-    await eventWait;
+    yield eventWait;
 
     ok(!gUI.table.items.has(rowName),
       `There is no row '${rowName}' in ${treeItemName} after deletion`);
   }
 
   // Final, we see that the default tab is intact or not.
-  await BrowserTestUtils.switchTab(gBrowser, tabDefault);
-  await openStoragePanel();
+  yield BrowserTestUtils.switchTab(gBrowser, tabDefault);
+  yield openStoragePanel();
 
   testTree(storageItemsForDefault);
-  await testTables(storageItemsForDefault);
+  yield testTables(storageItemsForDefault);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_dom_cache_disabled.js b/devtools/client/storage/test/browser_storage_dom_cache_disabled.js
index 2817e8df9132..27f9971a3f02 100644
--- a/devtools/client/storage/test/browser_storage_dom_cache_disabled.js
+++ b/devtools/client/storage/test/browser_storage_dom_cache_disabled.js
@@ -8,11 +8,11 @@
 
 // Test the storage inspector when dom.caches.enabled=false.
 
-add_task(async function () {
+add_task(function* () {
   // Disable the DOM cache
   Services.prefs.setBoolPref(DOM_CACHE, false);
 
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   const state = [
     [["localStorage", "http://test1.example.org"],
@@ -31,7 +31,7 @@ add_task(async function () {
       [1, 2, 3]],
   ];
 
-  await checkState(state);
+  yield checkState(state);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
index 6fb4d2a3f57b..b4ab388e8820 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
@@ -6,14 +6,14 @@
 
 // Test dynamic updates in the storage inspector for cookies.
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-updates.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-updates.html");
 
   gUI.tree.expandAll();
 
   ok(gUI.sidebar.hidden, "Sidebar is initially hidden");
   let c1id = getCookieId("c1", "test1.example.org", "/browser");
-  await selectTableItem(c1id);
+  yield selectTableItem(c1id);
 
   // test that value is something initially
   let initialValue = [[
@@ -36,12 +36,12 @@ add_task(async function () {
   ]];
 
   // Check that sidebar shows correct initial value
-  await findVariableViewProperties(initialValue[0], false);
+  yield findVariableViewProperties(initialValue[0], false);
 
-  await findVariableViewProperties(initialValue[1], true);
+  yield findVariableViewProperties(initialValue[1], true);
 
   // Check if table shows correct initial value
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -53,13 +53,13 @@ add_task(async function () {
   checkCell(c1id, "value", "1.2.3.4.5.6.7");
 
   gWindow.addCookie("c1", '{"foo": 4,"bar":6}', "/browser");
-  await gUI.once("sidebar-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("sidebar-updated");
+  yield gUI.once("store-objects-updated");
 
-  await findVariableViewProperties(finalValue[0], false);
-  await findVariableViewProperties(finalValue[1], true);
+  yield findVariableViewProperties(finalValue[0], false);
+  yield findVariableViewProperties(finalValue[1], true);
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -73,9 +73,9 @@ add_task(async function () {
   // Add a new entry
   gWindow.addCookie("c3", "booyeah");
 
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -94,10 +94,10 @@ add_task(async function () {
   gWindow.addCookie("c4", "booyeah");
 
   // Wait once for update and another time for value fetching
-  await gUI.once("store-objects-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -117,10 +117,10 @@ add_task(async function () {
   // Removing cookies
   gWindow.removeCookie("c1", "/browser");
 
-  await gUI.once("sidebar-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("sidebar-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -136,14 +136,14 @@ add_task(async function () {
   ok(!gUI.sidebar.hidden, "Sidebar still visible for next row");
 
   // Check if next element's value is visible in sidebar
-  await findVariableViewProperties([{name: "c2", value: "foobar"}]);
+  yield findVariableViewProperties([{name: "c2", value: "foobar"}]);
 
   // Keep deleting till no rows
   gWindow.removeCookie("c3");
 
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -155,14 +155,14 @@ add_task(async function () {
   ]);
 
   // Check if next element's value is visible in sidebar
-  await findVariableViewProperties([{name: "c2", value: "foobar"}]);
+  yield findVariableViewProperties([{name: "c2", value: "foobar"}]);
 
   gWindow.removeCookie("c2", "/browser");
 
-  await gUI.once("sidebar-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("sidebar-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["cookies", "http://test1.example.org"],
       [
@@ -173,17 +173,17 @@ add_task(async function () {
   ]);
 
   // Check if next element's value is visible in sidebar
-  await findVariableViewProperties([{name: "c4", value: "booyeah"}]);
+  yield findVariableViewProperties([{name: "c4", value: "booyeah"}]);
 
   gWindow.removeCookie("c4");
 
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [["cookies", "http://test1.example.org"], [ ]],
   ]);
 
   ok(gUI.sidebar.hidden, "Sidebar is hidden when no rows");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
index b93fe3b2911d..6980e3e55444 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
@@ -6,14 +6,14 @@
 
 // Test dynamic updates in the storage inspector for localStorage.
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-updates.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-updates.html");
 
   gUI.tree.expandAll();
 
   ok(gUI.sidebar.hidden, "Sidebar is initially hidden");
 
-  await checkState([
+  yield checkState([
     [
       ["localStorage", "http://test1.example.org"],
       ["ls1", "ls2", "ls3", "ls4", "ls5", "ls6", "ls7"]
@@ -22,9 +22,9 @@ add_task(async function () {
 
   gWindow.localStorage.removeItem("ls4");
 
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["localStorage", "http://test1.example.org"],
       ["ls1", "ls2", "ls3", "ls5", "ls6", "ls7"]
@@ -33,10 +33,10 @@ add_task(async function () {
 
   gWindow.localStorage.setItem("ls4", "again");
 
-  await gUI.once("store-objects-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["localStorage", "http://test1.example.org"],
       ["ls1", "ls2", "ls3", "ls4", "ls5", "ls6", "ls7"]
@@ -45,24 +45,24 @@ add_task(async function () {
   // Updating a row
   gWindow.localStorage.setItem("ls2", "ls2-changed");
 
-  await gUI.once("store-objects-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
   checkCell("ls2", "value", "ls2-changed");
 
   // Clearing items.
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, null, function () {
     content.wrappedJSObject.clear();
   });
 
-  await gUI.once("store-objects-cleared");
+  yield gUI.once("store-objects-cleared");
 
-  await checkState([
+  yield checkState([
     [
       ["localStorage", "http://test1.example.org"],
       [ ]
     ],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
index c00a6cb0e14d..bc2a2204cef9 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
@@ -6,14 +6,14 @@
 
 // Test dynamic updates in the storage inspector for sessionStorage.
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-updates.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-updates.html");
 
   gUI.tree.expandAll();
 
   ok(gUI.sidebar.hidden, "Sidebar is initially hidden");
 
-  await checkState([
+  yield checkState([
     [
       ["sessionStorage", "http://test1.example.org"],
       ["ss1", "ss2", "ss3"]
@@ -22,10 +22,10 @@ add_task(async function () {
 
   gWindow.sessionStorage.setItem("ss4", "new-item");
 
-  await gUI.once("store-objects-updated");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["sessionStorage", "http://test1.example.org"],
       ["ss1", "ss2", "ss3", "ss4"]
@@ -36,47 +36,47 @@ add_task(async function () {
 
   gWindow.sessionStorage.removeItem("ss3");
 
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
   gWindow.sessionStorage.removeItem("ss1");
 
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await checkState([
+  yield checkState([
     [
       ["sessionStorage", "http://test1.example.org"],
       ["ss2", "ss4"]
     ],
   ]);
 
-  await selectTableItem("ss2");
+  yield selectTableItem("ss2");
 
   ok(!gUI.sidebar.hidden, "sidebar is visible");
 
   // Checking for correct value in sidebar before update
-  await findVariableViewProperties([{name: "ss2", value: "foobar"}]);
+  yield findVariableViewProperties([{name: "ss2", value: "foobar"}]);
 
   gWindow.sessionStorage.setItem("ss2", "changed=ss2");
 
-  await gUI.once("sidebar-updated");
+  yield gUI.once("sidebar-updated");
 
   checkCell("ss2", "value", "changed=ss2");
 
-  await findVariableViewProperties([{name: "ss2", value: "changed=ss2"}]);
+  yield findVariableViewProperties([{name: "ss2", value: "changed=ss2"}]);
 
   // Clearing items.
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, null, function () {
     content.wrappedJSObject.clear();
   });
 
-  await gUI.once("store-objects-cleared");
+  yield gUI.once("store-objects-cleared");
 
-  await checkState([
+  yield checkState([
     [
       ["sessionStorage", "http://test1.example.org"],
       [ ]
     ],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_empty_objectstores.js b/devtools/client/storage/test/browser_storage_empty_objectstores.js
index 83b344be0931..e6f259742771 100644
--- a/devtools/client/storage/test/browser_storage_empty_objectstores.js
+++ b/devtools/client/storage/test/browser_storage_empty_objectstores.js
@@ -46,14 +46,14 @@ function testTree() {
 /**
  * Test that correct table entries are shown for each of the tree item
  */
-let testTables = async function () {
+let testTables = function* () {
   let doc = gPanelWindow.document;
   // Expand all nodes so that the synthesized click event actually works
   gUI.tree.expandAll();
 
   // Click the tree items and wait for the table to be updated
   for (let [item, ids] of storeItems) {
-    await selectTreeItem(item);
+    yield selectTreeItem(item);
 
     // Check whether correct number of items are present in the table
     is(doc.querySelectorAll(
@@ -68,10 +68,10 @@ let testTables = async function () {
   }
 };
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-empty-objectstores.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-empty-objectstores.html");
 
   testTree();
-  await testTables();
-  await finishTests();
+  yield testTables();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_delete.js b/devtools/client/storage/test/browser_storage_indexeddb_delete.js
index ec810ea38e2e..b4f5db7ed63e 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_delete.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_delete.js
@@ -8,21 +8,21 @@
 
 // Test deleting indexedDB database from the tree using context menu
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-empty-objectstores.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-empty-objectstores.html");
 
   let contextMenu = gPanelWindow.document.getElementById("storage-tree-popup");
   let menuDeleteDb = contextMenu.querySelector("#storage-tree-popup-delete");
 
   info("test state before delete");
-  await checkState([
+  yield checkState([
     [["indexedDB", "http://test1.example.org"], ["idb1 (default)", "idb2 (default)"]],
   ]);
 
   info("do the delete");
   const deletedDb = ["indexedDB", "http://test1.example.org", "idb1 (default)"];
 
-  await selectTreeItem(deletedDb);
+  yield selectTreeItem(deletedDb);
 
   // Wait once for update and another time for value fetching
   let eventWait = gUI.once("store-objects-updated").then(
@@ -31,17 +31,17 @@ add_task(async function () {
   let selector = `[data-id='${JSON.stringify(deletedDb)}'] > .tree-widget-item`;
   let target = gPanelWindow.document.querySelector(selector);
   ok(target, `tree item found in ${deletedDb.join(" > ")}`);
-  await waitForContextMenu(contextMenu, target, () => {
+  yield waitForContextMenu(contextMenu, target, () => {
     info(`Opened tree context menu in ${deletedDb.join(" > ")}`);
     menuDeleteDb.click();
   });
 
-  await eventWait;
+  yield eventWait;
 
   info("test state after delete");
-  await checkState([
+  yield checkState([
     [["indexedDB", "http://test1.example.org"], ["idb2 (default)"]],
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js b/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
index bb9a0a520d8f..b4c42bf288d0 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
@@ -8,51 +8,51 @@
 
 // Test what happens when deleting indexedDB database is blocked
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-idb-delete-blocked.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-idb-delete-blocked.html");
 
   info("test state before delete");
-  await checkState([
+  yield checkState([
     [["indexedDB", "http://test1.example.org"], ["idb (default)"]]
   ]);
 
   info("do the delete");
-  await selectTreeItem(["indexedDB", "http://test1.example.org"]);
+  yield selectTreeItem(["indexedDB", "http://test1.example.org"]);
   let front = gUI.getCurrentFront();
-  let result = await front.removeDatabase("http://test1.example.org", "idb (default)");
+  let result = yield front.removeDatabase("http://test1.example.org", "idb (default)");
 
   ok(result.blocked, "removeDatabase attempt is blocked");
 
   info("test state after blocked delete");
-  await checkState([
+  yield checkState([
     [["indexedDB", "http://test1.example.org"], ["idb (default)"]]
   ]);
 
   let eventWait = gUI.once("store-objects-updated");
 
   info("telling content to close the db");
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, async function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
     let win = content.wrappedJSObject;
-    await win.closeDb();
+    yield win.closeDb();
   });
 
   info("waiting for store update events");
-  await eventWait;
+  yield eventWait;
 
   info("test state after real delete");
-  await checkState([
+  yield checkState([
     [["indexedDB", "http://test1.example.org"], []]
   ]);
 
   info("try to delete database from nonexistent host");
   let errorThrown = false;
   try {
-    result = await front.removeDatabase("http://test2.example.org", "idb (default)");
+    result = yield front.removeDatabase("http://test2.example.org", "idb (default)");
   } catch (ex) {
     errorThrown = true;
   }
 
   ok(errorThrown, "error was reported when trying to delete");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_duplicate_names.js b/devtools/client/storage/test/browser_storage_indexeddb_duplicate_names.js
index 7a2e1afd882a..8316d22c5424 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_duplicate_names.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_duplicate_names.js
@@ -7,14 +7,14 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   const TESTPAGE = MAIN_DOMAIN + "storage-indexeddb-duplicate-names.html";
 
   setPermission(TESTPAGE, "indexedDB");
 
-  await openTabAndSetupStorage(TESTPAGE);
+  yield openTabAndSetupStorage(TESTPAGE);
 
-  await checkState([
+  yield checkState([
     [
       ["indexedDB", "http://test1.example.org"], [
         "idb1 (default)",
@@ -27,5 +27,5 @@ add_task(async function () {
     ]
   ]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_localstorage_add.js b/devtools/client/storage/test/browser_storage_localstorage_add.js
index 9f489fc25dc2..de40957b8848 100644
--- a/devtools/client/storage/test/browser_storage_localstorage_add.js
+++ b/devtools/client/storage/test/browser_storage_localstorage_add.js
@@ -6,15 +6,15 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-localstorage.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-localstorage.html");
   showAllColumns(true);
 
-  await performAdd(["localStorage", "http://test1.example.org"]);
-  await performAdd(["localStorage", "http://test1.example.org"]);
-  await performAdd(["localStorage", "http://test1.example.org"]);
-  await performAdd(["localStorage", "http://test1.example.org"]);
-  await performAdd(["localStorage", "http://test1.example.org"]);
+  yield performAdd(["localStorage", "http://test1.example.org"]);
+  yield performAdd(["localStorage", "http://test1.example.org"]);
+  yield performAdd(["localStorage", "http://test1.example.org"]);
+  yield performAdd(["localStorage", "http://test1.example.org"]);
+  yield performAdd(["localStorage", "http://test1.example.org"]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_localstorage_edit.js b/devtools/client/storage/test/browser_storage_localstorage_edit.js
index 54baa392cdf3..86409e0ac626 100644
--- a/devtools/client/storage/test/browser_storage_localstorage_edit.js
+++ b/devtools/client/storage/test/browser_storage_localstorage_edit.js
@@ -6,19 +6,19 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-localstorage.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-localstorage.html");
 
-  await selectTreeItem(["localStorage", "http://test1.example.org"]);
+  yield selectTreeItem(["localStorage", "http://test1.example.org"]);
 
-  await editCell("TestLS1", "name", "newTestLS1");
-  await editCell("newTestLS1", "value", "newValueLS1");
+  yield editCell("TestLS1", "name", "newTestLS1");
+  yield editCell("newTestLS1", "value", "newValueLS1");
 
-  await editCell("TestLS3", "name", "newTestLS3");
-  await editCell("newTestLS3", "value", "newValueLS3");
+  yield editCell("TestLS3", "name", "newTestLS3");
+  yield editCell("newTestLS3", "value", "newValueLS3");
 
-  await editCell("TestLS5", "name", "newTestLS5");
-  await editCell("newTestLS5", "value", "newValueLS5");
+  yield editCell("TestLS5", "name", "newTestLS5");
+  yield editCell("newTestLS5", "value", "newValueLS5");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_localstorage_error.js b/devtools/client/storage/test/browser_storage_localstorage_error.js
index 70cb94e7b979..923ca6ca958b 100644
--- a/devtools/client/storage/test/browser_storage_localstorage_error.js
+++ b/devtools/client/storage/test/browser_storage_localstorage_error.js
@@ -7,8 +7,8 @@
 // Test that for pages where local/sessionStorage is not available (like about:home),
 // the host still appears in the storage tree and no unhandled exception is thrown.
 
-add_task(async function () {
-  await openTabAndSetupStorage("about:home");
+add_task(function* () {
+  yield openTabAndSetupStorage("about:home");
 
   let itemsToOpen = [
     ["localStorage", "about:home"],
@@ -16,9 +16,9 @@ add_task(async function () {
   ];
 
   for (let item of itemsToOpen) {
-    await selectTreeItem(item);
+    yield selectTreeItem(item);
     ok(gUI.tree.isSelected(item), `Item ${item.join(" > ")} is present in the tree`);
   }
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_overflow.js b/devtools/client/storage/test/browser_storage_overflow.js
index b2aad85416d9..0dd7f2551423 100644
--- a/devtools/client/storage/test/browser_storage_overflow.js
+++ b/devtools/client/storage/test/browser_storage_overflow.js
@@ -4,17 +4,17 @@
 
 const ITEMS_PER_PAGE = 50;
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-overflow.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-overflow.html");
 
   gUI.tree.expandAll();
-  await selectTreeItem(["localStorage", "http://test1.example.org"]);
+  yield selectTreeItem(["localStorage", "http://test1.example.org"]);
   checkCellLength(ITEMS_PER_PAGE);
 
-  await scroll();
+  yield scroll();
   checkCellLength(ITEMS_PER_PAGE * 2);
 
-  await scroll();
+  yield scroll();
   checkCellLength(ITEMS_PER_PAGE * 3);
 
   // Check that the columns are sorted in a human readable way (ascending).
@@ -26,7 +26,7 @@ add_task(async function () {
   // Check that the columns are sorted in a human readable way (descending).
   checkCellValues("DEC");
 
-  await finishTests();
+  yield finishTests();
 });
 
 function checkCellLength(len) {
@@ -46,7 +46,7 @@ function checkCellValues(order) {
   });
 }
 
-async function scroll() {
+function* scroll() {
   let $ = id => gPanelWindow.document.querySelector(id);
   let table = $("#storage-table .table-widget-body");
   let cell = $("#name .table-widget-cell");
@@ -54,5 +54,5 @@ async function scroll() {
 
   let onStoresUpdate = gUI.once("store-objects-updated");
   table.scrollTop += cellHeight * 50;
-  await onStoresUpdate;
+  yield onStoresUpdate;
 }
diff --git a/devtools/client/storage/test/browser_storage_search.js b/devtools/client/storage/test/browser_storage_search.js
index 445515fa0009..148f2eeb5e77 100644
--- a/devtools/client/storage/test/browser_storage_search.js
+++ b/devtools/client/storage/test/browser_storage_search.js
@@ -1,11 +1,11 @@
 // Tests the filter search box in the storage inspector
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-search.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-search.html");
 
   gUI.tree.expandAll();
-  await selectTreeItem(["cookies", "http://test1.example.org"]);
+  yield selectTreeItem(["cookies", "http://test1.example.org"]);
 
   showColumn("expires", false);
   showColumn("host", false);
@@ -113,7 +113,7 @@ add_task(async function () {
   showColumn("value", false);
   runTests(testcasesAfterHiding);
 
-  await finishTests();
+  yield finishTests();
 });
 
 function runTests(testcases) {
diff --git a/devtools/client/storage/test/browser_storage_search_keyboard_trap.js b/devtools/client/storage/test/browser_storage_search_keyboard_trap.js
index c74cd1737aad..71dfd32c0030 100644
--- a/devtools/client/storage/test/browser_storage_search_keyboard_trap.js
+++ b/devtools/client/storage/test/browser_storage_search_keyboard_trap.js
@@ -1,15 +1,15 @@
 // Test ability to focus search field by using keyboard
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-search.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-search.html");
 
   gUI.tree.expandAll();
-  await selectTreeItem(["localStorage", "http://test1.example.org"]);
+  yield selectTreeItem(["localStorage", "http://test1.example.org"]);
 
-  await focusSearchBoxUsingShortcut(gPanelWindow);
+  yield focusSearchBoxUsingShortcut(gPanelWindow);
   ok(containsFocus(gPanelWindow.document, gUI.searchBox),
      "Focus is in a searchbox");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_sessionstorage_add.js b/devtools/client/storage/test/browser_storage_sessionstorage_add.js
index 974f4dbc55c1..8f220bc81eb9 100644
--- a/devtools/client/storage/test/browser_storage_sessionstorage_add.js
+++ b/devtools/client/storage/test/browser_storage_sessionstorage_add.js
@@ -6,15 +6,15 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-sessionstorage.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-sessionstorage.html");
   showAllColumns(true);
 
-  await performAdd(["sessionStorage", "http://test1.example.org"]);
-  await performAdd(["sessionStorage", "http://test1.example.org"]);
-  await performAdd(["sessionStorage", "http://test1.example.org"]);
-  await performAdd(["sessionStorage", "http://test1.example.org"]);
-  await performAdd(["sessionStorage", "http://test1.example.org"]);
+  yield performAdd(["sessionStorage", "http://test1.example.org"]);
+  yield performAdd(["sessionStorage", "http://test1.example.org"]);
+  yield performAdd(["sessionStorage", "http://test1.example.org"]);
+  yield performAdd(["sessionStorage", "http://test1.example.org"]);
+  yield performAdd(["sessionStorage", "http://test1.example.org"]);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_sessionstorage_edit.js b/devtools/client/storage/test/browser_storage_sessionstorage_edit.js
index 8405f57dbf7d..9629eec0b523 100644
--- a/devtools/client/storage/test/browser_storage_sessionstorage_edit.js
+++ b/devtools/client/storage/test/browser_storage_sessionstorage_edit.js
@@ -6,19 +6,19 @@
 
 "use strict";
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-sessionstorage.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-sessionstorage.html");
 
-  await selectTreeItem(["sessionStorage", "http://test1.example.org"]);
+  yield selectTreeItem(["sessionStorage", "http://test1.example.org"]);
 
-  await editCell("TestSS1", "name", "newTestSS1");
-  await editCell("newTestSS1", "value", "newValueSS1");
+  yield editCell("TestSS1", "name", "newTestSS1");
+  yield editCell("newTestSS1", "value", "newValueSS1");
 
-  await editCell("TestSS3", "name", "newTestSS3");
-  await editCell("newTestSS3", "value", "newValueSS3");
+  yield editCell("TestSS3", "name", "newTestSS3");
+  yield editCell("newTestSS3", "value", "newValueSS3");
 
-  await editCell("TestSS5", "name", "newTestSS5");
-  await editCell("newTestSS5", "value", "newValueSS5");
+  yield editCell("TestSS5", "name", "newTestSS5");
+  yield editCell("newTestSS5", "value", "newValueSS5");
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_sidebar.js b/devtools/client/storage/test/browser_storage_sidebar.js
index 820aacc452f0..bc5f130d7b91 100644
--- a/devtools/client/storage/test/browser_storage_sidebar.js
+++ b/devtools/client/storage/test/browser_storage_sidebar.js
@@ -97,8 +97,8 @@ const testCases = [
   }
 ];
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   for (let test of testCases) {
     let { location, sidebarHidden, sendEscape } = test;
@@ -106,9 +106,9 @@ add_task(async function () {
     info("running " + JSON.stringify(test));
 
     if (Array.isArray(location)) {
-      await selectTreeItem(location);
+      yield selectTreeItem(location);
     } else if (location) {
-      await selectTableItem(location);
+      yield selectTableItem(location);
     }
 
     if (sendEscape) {
@@ -121,5 +121,5 @@ add_task(async function () {
     info("-".repeat(80));
   }
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_sidebar_toggle.js b/devtools/client/storage/test/browser_storage_sidebar_toggle.js
index c69beb3e6276..cecc67c15b1b 100644
--- a/devtools/client/storage/test/browser_storage_sidebar_toggle.js
+++ b/devtools/client/storage/test/browser_storage_sidebar_toggle.js
@@ -26,8 +26,8 @@ const testCases = [
   }
 ];
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-listings.html");
 
   for (let test of testCases) {
     let { location, sidebarHidden, clickToggle, toggleButtonVisible } = test;
@@ -35,9 +35,9 @@ add_task(async function () {
     info("running " + JSON.stringify(test));
 
     if (Array.isArray(location)) {
-      await selectTreeItem(location);
+      yield selectTreeItem(location);
     } else if (location) {
-      await selectTableItem(location);
+      yield selectTableItem(location);
     }
 
     if (clickToggle) {
@@ -53,5 +53,5 @@ add_task(async function () {
     info("-".repeat(80));
   }
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_sidebar_update.js b/devtools/client/storage/test/browser_storage_sidebar_update.js
index 992f457f242d..92547815a425 100644
--- a/devtools/client/storage/test/browser_storage_sidebar_update.js
+++ b/devtools/client/storage/test/browser_storage_sidebar_update.js
@@ -8,16 +8,16 @@
 
 "use strict";
 
-add_task(async function () {
+add_task(function* () {
   const ITEM_NAME = "ls1";
   const UPDATE_COUNT = 3;
 
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-complex-values.html");
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-complex-values.html");
 
   let updated = gUI.once("sidebar-updated");
-  await selectTreeItem(["localStorage", "http://test1.example.org"]);
-  await selectTableItem(ITEM_NAME);
-  await updated;
+  yield selectTreeItem(["localStorage", "http://test1.example.org"]);
+  yield selectTableItem(ITEM_NAME);
+  yield updated;
 
   is(gUI.sidebar.hidden, false, "sidebar is visible");
 
@@ -28,7 +28,7 @@ add_task(async function () {
     updates.push(gUI.once("sidebar-updated"));
     gUI.updateObjectSidebar();
   }
-  await promise.all(updates);
+  yield promise.all(updates);
 
   info("Updates performed, going to verify result");
   let parsedScope = gUI.view.getScopeAtIndex(1);
@@ -37,5 +37,5 @@ add_task(async function () {
   is(elements.length, 1,
     `There is only one displayed variable named '${ITEM_NAME}'`);
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/browser_storage_values.js b/devtools/client/storage/test/browser_storage_values.js
index 748ece67634b..1d3e9ff76e7b 100644
--- a/devtools/client/storage/test/browser_storage_values.js
+++ b/devtools/client/storage/test/browser_storage_values.js
@@ -147,8 +147,8 @@ const testCases = [
   ], true]
 ];
 
-add_task(async function () {
-  await openTabAndSetupStorage(MAIN_DOMAIN + "storage-complex-values.html");
+add_task(function* () {
+  yield openTabAndSetupStorage(MAIN_DOMAIN + "storage-complex-values.html");
 
   gUI.tree.expandAll();
 
@@ -156,14 +156,14 @@ add_task(async function () {
     info("clicking for item " + item);
 
     if (Array.isArray(item[0])) {
-      await selectTreeItem(item[0]);
+      yield selectTreeItem(item[0]);
       continue;
     } else if (item[0]) {
-      await selectTableItem(item[0]);
+      yield selectTableItem(item[0]);
     }
 
-    await findVariableViewProperties(item[1], item[2]);
+    yield findVariableViewProperties(item[1], item[2]);
   }
 
-  await finishTests();
+  yield finishTests();
 });
diff --git a/devtools/client/storage/test/head.js b/devtools/client/storage/test/head.js
index 041b5e364cea..5d51c855c09b 100644
--- a/devtools/client/storage/test/head.js
+++ b/devtools/client/storage/test/head.js
@@ -55,14 +55,14 @@ registerCleanupFunction(() => {
  *
  * @return {Promise} A promise that resolves after the tab is ready
  */
-async function openTab(url, options = {}) {
-  let tab = await addTab(url, options);
+function* openTab(url, options = {}) {
+  let tab = yield addTab(url, options);
   let content = tab.linkedBrowser.contentWindowAsCPOW;
 
   gWindow = content.wrappedJSObject;
 
   // Setup the async storages in main window and for all its iframes
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, async function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
     /**
      * Get all windows including frames recursively.
      *
@@ -92,7 +92,7 @@ async function openTab(url, options = {}) {
       let readyState = win.document.readyState;
       info(`Found a window: ${readyState}`);
       if (readyState != "complete") {
-        await new Promise(resolve => {
+        yield new Promise(resolve => {
           let onLoad = () => {
             win.removeEventListener("load", onLoad);
             resolve();
@@ -101,7 +101,7 @@ async function openTab(url, options = {}) {
         });
       }
       if (win.setup) {
-        await win.setup();
+        yield win.setup();
       }
     }
   });
@@ -120,12 +120,12 @@ async function openTab(url, options = {}) {
  *
  * @return {Promise} A promise that resolves after storage inspector is ready
  */
-async function openTabAndSetupStorage(url, options = {}) {
+function* openTabAndSetupStorage(url, options = {}) {
   // open tab
-  await openTab(url, options);
+  yield openTab(url, options);
 
   // open storage inspector
-  return openStoragePanel();
+  return yield openStoragePanel();
 }
 
 /**
@@ -136,7 +136,7 @@ async function openTabAndSetupStorage(url, options = {}) {
  *
  * @return {Promise} a promise that resolves when the storage inspector is ready
  */
-var openStoragePanel = async function (cb) {
+var openStoragePanel = Task.async(function* (cb) {
   info("Opening the storage inspector");
   let target = TargetFactory.forTab(gBrowser.selectedTab);
 
@@ -165,7 +165,7 @@ var openStoragePanel = async function (cb) {
   }
 
   info("Opening the toolbox");
-  toolbox = await gDevTools.showToolbox(target, "storage");
+  toolbox = yield gDevTools.showToolbox(target, "storage");
   storage = toolbox.getPanel("storage");
   gPanelWindow = storage.panelWindow;
   gUI = storage.UI;
@@ -176,9 +176,9 @@ var openStoragePanel = async function (cb) {
   gUI.animationsEnabled = false;
 
   info("Waiting for the stores to update");
-  await gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
-  await waitForToolboxFrameFocus(toolbox);
+  yield waitForToolboxFrameFocus(toolbox);
 
   if (cb) {
     return cb(storage, toolbox);
@@ -188,7 +188,7 @@ var openStoragePanel = async function (cb) {
     toolbox: toolbox,
     storage: storage
   };
-};
+});
 
 /**
  * Wait for the toolbox frame to receive focus after it loads
@@ -218,11 +218,11 @@ function forceCollections() {
 /**
  * Cleans up and finishes the test
  */
-async function finishTests() {
+function* finishTests() {
   // Bug 1233497 makes it so that we can no longer yield CPOWs from Tasks.
   // We work around this by calling clear() via a ContentTask instead.
   while (gBrowser.tabs.length > 1) {
-    await ContentTask.spawn(gBrowser.selectedBrowser, null, async function () {
+    yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
       /**
        * Get all windows including frames recursively.
        *
@@ -258,12 +258,12 @@ async function finishTests() {
         }
 
         if (win.clear) {
-          await win.clear();
+          yield win.clear();
         }
       }
     });
 
-    await closeTabAndToolbox(gBrowser.selectedTab);
+    yield closeTabAndToolbox(gBrowser.selectedTab);
   }
 
   Services.cookies.removeAll();
@@ -272,7 +272,7 @@ async function finishTests() {
 }
 
 // Sends a click event on the passed DOM node in an async manner
-function click(node) {
+function* click(node) {
   node.scrollIntoView();
 
   return new Promise(resolve => {
@@ -511,7 +511,7 @@ function matchVariablesViewProperty(prop, rule) {
  * @param {[String]} ids
  *        The array id of the item in the tree
  */
-async function selectTreeItem(ids) {
+function* selectTreeItem(ids) {
   /* If this item is already selected, return */
   if (gUI.tree.isSelected(ids)) {
     return;
@@ -519,7 +519,7 @@ async function selectTreeItem(ids) {
 
   let updated = gUI.once("store-objects-updated");
   gUI.tree.selectedItem = ids;
-  await updated;
+  yield updated;
 }
 
 /**
@@ -528,7 +528,7 @@ async function selectTreeItem(ids) {
  * @param {String} id
  *        The id of the row in the table widget
  */
-async function selectTableItem(id) {
+function* selectTableItem(id) {
   let table = gUI.table;
   let selector = ".table-widget-column#" + table.uniqueId +
                  " .table-widget-cell[value='" + id + "']";
@@ -542,8 +542,8 @@ async function selectTableItem(id) {
 
   let updated = gUI.once("sidebar-updated");
 
-  await click(target);
-  await updated;
+  yield click(target);
+  yield updated;
 }
 
 /**
@@ -703,13 +703,13 @@ function getCellValue(id, column) {
  * @yield {String}
  *        The uniqueId of the changed row.
  */
-async function editCell(id, column, newValue, validate = true) {
+function* editCell(id, column, newValue, validate = true) {
   let row = getRowCells(id, true);
   let editableFieldsEngine = gUI.table._editableFieldsEngine;
 
   editableFieldsEngine.edit(row[column]);
 
-  await typeWithTerminator(newValue, "KEY_Enter", validate);
+  yield typeWithTerminator(newValue, "KEY_Enter", validate);
 }
 
 /**
@@ -722,7 +722,7 @@ async function editCell(id, column, newValue, validate = true) {
  * @param {Boolean} selectText
  *        Select text? Default true.
  */
-function startCellEdit(id, column, selectText = true) {
+function* startCellEdit(id, column, selectText = true) {
   let row = getRowCells(id, true);
   let editableFieldsEngine = gUI.table._editableFieldsEngine;
   let cell = row[column];
@@ -812,7 +812,7 @@ function showAllColumns(state) {
  * @param  {Boolean} validate
  *         Validate result? Default true.
  */
-async function typeWithTerminator(str, terminator, validate = true) {
+function* typeWithTerminator(str, terminator, validate = true) {
   let editableFieldsEngine = gUI.table._editableFieldsEngine;
   let textbox = editableFieldsEngine.textbox;
   let colName = textbox.closest(".table-widget-column").id;
@@ -831,13 +831,13 @@ async function typeWithTerminator(str, terminator, validate = true) {
 
   if (validate) {
     info("Validating results... waiting for ROW_EDIT event.");
-    let uniqueId = await gUI.table.once(TableWidget.EVENTS.ROW_EDIT);
+    let uniqueId = yield gUI.table.once(TableWidget.EVENTS.ROW_EDIT);
 
     checkCell(uniqueId, colName, str);
     return uniqueId;
   }
 
-  return gUI.table.once(TableWidget.EVENTS.ROW_EDIT);
+  return yield gUI.table.once(TableWidget.EVENTS.ROW_EDIT);
 }
 
 function getCurrentEditorValue() {
@@ -872,11 +872,11 @@ function PressKeyXTimes(key, x, modifiers = {}) {
  *        "example.com" host in cookies and then verify there are "c1" and "c2"
  *        cookies (and no other ones).
  */
-async function checkState(state) {
+function* checkState(state) {
   for (let [store, names] of state) {
     let storeName = store.join(" > ");
     info(`Selecting tree item ${storeName}`);
-    await selectTreeItem(store);
+    yield selectTreeItem(store);
 
     let items = gUI.table.items;
 
@@ -915,7 +915,7 @@ function containsFocus(doc, container) {
   return false;
 }
 
-var focusSearchBoxUsingShortcut = async function (panelWin, callback) {
+var focusSearchBoxUsingShortcut = Task.async(function* (panelWin, callback) {
   info("Focusing search box");
   let searchBox = panelWin.document.getElementById("storage-searchbox");
   let focused = once(searchBox, "focus");
@@ -925,12 +925,12 @@ var focusSearchBoxUsingShortcut = async function (panelWin, callback) {
     "chrome://devtools/locale/storage.properties");
   synthesizeKeyShortcut(strings.GetStringFromName("storage.filter.key"));
 
-  await focused;
+  yield focused;
 
   if (callback) {
     callback();
   }
-};
+});
 
 function getCookieId(name, domain, path) {
   return `${name}${SEPARATOR_GUID}${domain}${SEPARATOR_GUID}${path}`;
@@ -962,12 +962,12 @@ function sidebarToggleVisible() {
  *         An array containing the path to the store to which we wish to add an
  *         item.
  */
-async function performAdd(store) {
+function* performAdd(store) {
   let storeName = store.join(" > ");
   let toolbar = gPanelWindow.document.getElementById("storage-toolbar");
   let type = store[0];
 
-  await selectTreeItem(store);
+  yield selectTreeItem(store);
 
   let menuAdd = toolbar.querySelector(
     "#add-button");
@@ -983,8 +983,8 @@ async function performAdd(store) {
 
   menuAdd.click();
 
-  let rowId = await eventEdit;
-  await eventWait;
+  let rowId = yield eventEdit;
+  yield eventWait;
 
   let key = type === "cookies" ? "uniqueKey" : "name";
   let value = getCellValue(rowId, key);
diff --git a/devtools/client/storage/test/storage-complex-values.html b/devtools/client/storage/test/storage-complex-values.html
index 82faab8e09bb..91e04c6edf7c 100644
--- a/devtools/client/storage/test/storage-complex-values.html
+++ b/devtools/client/storage/test/storage-complex-values.html
@@ -1,4 +1,4 @@
-<!DOCTYPE HTML>
+<!DOCTYPE HTML>
 <html>
 <!--
 Bug 970517 - Storage inspector front end - tests
@@ -42,12 +42,12 @@ let s = "a".repeat(1000);
 sessionStorage.setItem("ss5", `${s}=${s}=${s}=${s}&${s}=${s}&${s}`);
 console.log("added cookies and stuff from main page");
 
-let idbGenerator = async function () {
+let idbGenerator = function*() {
   let request = indexedDB.open("idb1", 1);
   request.onerror = function() {
     throw new Error("error opening db connection");
   };
-  let db = await new Promise(done => {
+  let db = yield new Promise(done => {
     request.onupgradeneeded = event => {
       let db = event.target.result;
       let store1 = db.createObjectStore("obj1", { keyPath: "id" });
@@ -61,7 +61,7 @@ let idbGenerator = async function () {
   });
 
   // Prevents AbortError
-  await new Promise(done => {
+  yield new Promise(done => {
     request.onsuccess = done;
   });
 
@@ -81,7 +81,7 @@ let idbGenerator = async function () {
   db.close();
 
   request = indexedDB.open("idb2", 1);
-  let db2 = await new Promise(done => {
+  let db2 = yield new Promise(done => {
     request.onupgradeneeded = event => {
       let db2 = event.target.result;
       let store3 = db2.createObjectStore("obj3", { keyPath: "id3" });
@@ -93,7 +93,7 @@ let idbGenerator = async function () {
   });
 
   // Prevents AbortError during close()
-  await new Promise(done => {
+  yield new Promise(done => {
     request.onsuccess = done;
   });
 
@@ -108,13 +108,13 @@ function deleteDB(dbName) {
   });
 }
 
-window.setup = async function () {
-  await idbGenerator();
+window.setup = function*() {
+  yield idbGenerator();
 };
 
-window.clear = async function () {
-  await deleteDB("idb1");
-  await deleteDB("idb2");
+window.clear = function*() {
+  yield deleteDB("idb1");
+  yield deleteDB("idb2");
 
   dump("removed indexedDB data from " + document.location + "\n");
 };
diff --git a/devtools/client/storage/test/storage-empty-objectstores.html b/devtools/client/storage/test/storage-empty-objectstores.html
index 7e84cea4728f..a36cef23872e 100644
--- a/devtools/client/storage/test/storage-empty-objectstores.html
+++ b/devtools/client/storage/test/storage-empty-objectstores.html
@@ -7,9 +7,9 @@
 <body>
 <script type="application/javascript">
 
-window.setup = async function () {
+window.setup = function* () {
   let request = indexedDB.open("idb1", 1);
-  let db = await new Promise((resolve, reject) => {
+  let db = yield new Promise((resolve, reject) => {
     request.onerror = e => reject(Error("error opening db connection"));
     request.onupgradeneeded = event => {
       let db = event.target.result;
@@ -21,7 +21,7 @@ window.setup = async function () {
     };
   });
 
-  await new Promise(resolve => request.onsuccess = resolve);
+  yield new Promise(resolve => request.onsuccess = resolve);
 
   let transaction = db.transaction(["obj1", "obj2"], "readwrite");
   let store1 = transaction.objectStore("obj1");
@@ -32,25 +32,25 @@ window.setup = async function () {
   store1.add({id: 3, name: "foo2", email: "foo3@bar.com"});
   store2.add({id2: 1, name: "foo", email: "foo@bar.com", extra: "baz"});
 
-  await new Promise(resolve => transaction.oncomplete = resolve);
+  yield new Promise(resolve => transaction.oncomplete = resolve);
 
   db.close();
 
   request = indexedDB.open("idb2", 1);
-  let db2 = await new Promise((resolve, reject) => {
+  let db2 = yield new Promise((resolve, reject) => {
     request.onerror = e => reject(Error("error opening db2 connection"));
     request.onupgradeneeded = event => resolve(event.target.result);
   });
 
-  await new Promise(resolve => request.onsuccess = resolve);
+  yield new Promise(resolve => request.onsuccess = resolve);
 
   db2.close();
   dump("added indexedDB items from main page\n");
 };
 
-window.clear = async function () {
+window.clear = function* () {
   for (let dbName of ["idb1", "idb2"]) {
-    await new Promise(resolve => {
+    yield new Promise(resolve => {
       indexedDB.deleteDatabase(dbName).onsuccess = resolve;
     });
   }
diff --git a/devtools/client/storage/test/storage-idb-delete-blocked.html b/devtools/client/storage/test/storage-idb-delete-blocked.html
index d688ac2c736f..79c9e01afa55 100644
--- a/devtools/client/storage/test/storage-idb-delete-blocked.html
+++ b/devtools/client/storage/test/storage-idb-delete-blocked.html
@@ -9,8 +9,8 @@
 
 let db;
 
-window.setup = async function () {
-  db = await new Promise((resolve, reject) => {
+window.setup = function* () {
+  db = yield new Promise((resolve, reject) => {
     let request = indexedDB.open("idb", 1);
 
     request.onsuccess = e => resolve(e.target.result);
@@ -25,12 +25,12 @@ window.setup = async function () {
   dump("opened indexedDB\n");
 };
 
-window.closeDb = function() {
+window.closeDb = function* () {
   db.close();
 };
 
-window.deleteDb = async function () {
-  await new Promise((resolve, reject) => {
+window.deleteDb = function* () {
+  yield new Promise((resolve, reject) => {
     let request = indexedDB.deleteDatabase("idb");
 
     request.onsuccess = resolve;
@@ -38,9 +38,9 @@ window.deleteDb = async function () {
   });
 };
 
-window.clear = async function () {
+window.clear = function* () {
   for (let dbName of ["idb1", "idb2"]) {
-    await new Promise(resolve => {
+    yield new Promise(resolve => {
       indexedDB.deleteDatabase(dbName).onsuccess = resolve;
     });
   }
diff --git a/devtools/client/storage/test/storage-indexeddb-duplicate-names.html b/devtools/client/storage/test/storage-indexeddb-duplicate-names.html
index 52c9db4b48e5..ea009e302604 100644
--- a/devtools/client/storage/test/storage-indexeddb-duplicate-names.html
+++ b/devtools/client/storage/test/storage-indexeddb-duplicate-names.html
@@ -32,13 +32,13 @@
       });
     }
 
-    window.clear = async function () {
-      await deleteDB("idb1", "temporary");
-      await deleteDB("idb1", "default");
-      await deleteDB("idb1", "persistent");
-      await deleteDB("idb2", "temporary");
-      await deleteDB("idb2", "default");
-      await deleteDB("idb2", "persistent");
+    window.clear = function* () {
+      yield deleteDB("idb1", "temporary");
+      yield deleteDB("idb1", "default");
+      yield deleteDB("idb1", "persistent");
+      yield deleteDB("idb2", "temporary");
+      yield deleteDB("idb2", "default");
+      yield deleteDB("idb2", "persistent");
 
       dump(`removed indexedDB data from ${document.location}\n`);
     };
diff --git a/devtools/client/storage/test/storage-listings-usercontextid.html b/devtools/client/storage/test/storage-listings-usercontextid.html
index b1e30c48a956..c8c15ea63aa8 100644
--- a/devtools/client/storage/test/storage-listings-usercontextid.html
+++ b/devtools/client/storage/test/storage-listings-usercontextid.html
@@ -28,7 +28,7 @@ localStorage.setItem("ls2uc1", "foobar-2");
 sessionStorage.setItem("ss1uc1", "foobar-3");
 dump("added cookies and storage from main page\n");
 
-let idbGenerator = async function () {
+let idbGenerator = async function() {
   let request = indexedDB.open("idb1uc1", 1);
   request.onerror = function() {
     throw new Error("error opening db connection");
@@ -102,26 +102,26 @@ async function fetchPut(cache, url) {
   await cache.put(url, response);
 }
 
-let cacheGenerator = async function () {
+let cacheGenerator = async function() {
   let cache = await caches.open("plopuc1");
   await fetchPut(cache, "404_cached_file.js");
   await fetchPut(cache, "browser_storage_basic.js");
 };
 
-window.setup = async function () {
-  await idbGenerator();
+window.setup = function*() {
+  yield idbGenerator();
 
   if (window.caches) {
-    await cacheGenerator();
+    yield cacheGenerator();
   }
 };
 
-window.clear = async function () {
-  await deleteDB("idb1uc1");
-  await deleteDB("idb2uc1");
+window.clear = function*() {
+  yield deleteDB("idb1uc1");
+  yield deleteDB("idb2uc1");
 
   if (window.caches) {
-    await caches.delete("plopuc1");
+    yield caches.delete("plopuc1");
   }
 
   dump("removed indexedDB and cache data from " + document.location + "\n");
diff --git a/devtools/client/storage/test/storage-listings-with-fragment.html b/devtools/client/storage/test/storage-listings-with-fragment.html
index 5c0206a963ef..4eb5248d5224 100644
--- a/devtools/client/storage/test/storage-listings-with-fragment.html
+++ b/devtools/client/storage/test/storage-listings-with-fragment.html
@@ -1,4 +1,4 @@
-<!DOCTYPE HTML>
+<!DOCTYPE HTML>
 <html>
 <!--
 This test differs from browser_storage_listings.html only because the URLs we load
@@ -31,7 +31,7 @@ localStorage.setItem("ls2", "foobar-2");
 sessionStorage.setItem("ss1", "foobar-3");
 dump("added cookies and storage from main page\n");
 
-let idbGenerator = async function () {
+let idbGenerator = async function() {
   let request = indexedDB.open("idb1", 1);
   request.onerror = function() {
     throw new Error("error opening db connection");
@@ -105,26 +105,26 @@ async function fetchPut(cache, url) {
   await cache.put(url, response);
 }
 
-let cacheGenerator = async function () {
+let cacheGenerator = async function() {
   let cache = await caches.open("plop");
   await fetchPut(cache, "404_cached_file.js");
   await fetchPut(cache, "browser_storage_basic.js");
 };
 
-window.setup = async function () {
-  await idbGenerator();
+window.setup = function*() {
+  yield idbGenerator();
 
   if (window.caches) {
-    await cacheGenerator();
+    yield cacheGenerator();
   }
 };
 
-window.clear = async function () {
-  await deleteDB("idb1");
-  await deleteDB("idb2");
+window.clear = function*() {
+  yield deleteDB("idb1");
+  yield deleteDB("idb2");
 
   if (window.caches) {
-    await caches.delete("plop");
+    yield caches.delete("plop");
   }
 
   dump("removed indexedDB and cache data from " + document.location + "\n");
diff --git a/devtools/client/storage/test/storage-listings.html b/devtools/client/storage/test/storage-listings.html
index 52aae75e9277..d50c9b5514ab 100644
--- a/devtools/client/storage/test/storage-listings.html
+++ b/devtools/client/storage/test/storage-listings.html
@@ -1,4 +1,4 @@
-<!DOCTYPE HTML>
+<!DOCTYPE HTML>
 <html>
 <!--
 Storage inspector front end - tests
@@ -31,7 +31,7 @@ localStorage.setItem("ls2", "foobar-2");
 sessionStorage.setItem("ss1", "foobar-3");
 dump("added cookies and storage from main page\n");
 
-let idbGenerator = async function () {
+let idbGenerator = async function() {
   let request = indexedDB.open("idb1", 1);
   request.onerror = function() {
     throw new Error("error opening db connection");
@@ -105,26 +105,26 @@ async function fetchPut(cache, url) {
   await cache.put(url, response);
 }
 
-let cacheGenerator = async function () {
+let cacheGenerator = async function() {
   let cache = await caches.open("plop");
   await fetchPut(cache, "404_cached_file.js");
   await fetchPut(cache, "browser_storage_basic.js");
 };
 
-window.setup = async function () {
-  await idbGenerator();
+window.setup = function*() {
+  yield idbGenerator();
 
   if (window.caches) {
-    await cacheGenerator();
+    yield cacheGenerator();
   }
 };
 
-window.clear = async function () {
-  await deleteDB("idb1");
-  await deleteDB("idb2");
+window.clear = function*() {
+  yield deleteDB("idb1");
+  yield deleteDB("idb2");
 
   if (window.caches) {
-    await caches.delete("plop");
+    yield caches.delete("plop");
   }
 
   dump("removed indexedDB and cache data from " + document.location + "\n");
diff --git a/devtools/client/storage/test/storage-secured-iframe-usercontextid.html b/devtools/client/storage/test/storage-secured-iframe-usercontextid.html
index f30b97402b2a..42f01a6c7476 100644
--- a/devtools/client/storage/test/storage-secured-iframe-usercontextid.html
+++ b/devtools/client/storage/test/storage-secured-iframe-usercontextid.html
@@ -14,12 +14,12 @@ localStorage.setItem("iframe-s-ls1uc1", "foobar");
 sessionStorage.setItem("iframe-s-ss1uc1", "foobar-2");
 dump("added cookies and storage from secured iframe\n");
 
-let idbGenerator = async function () {
+let idbGenerator = function*() {
   let request = indexedDB.open("idb-s1uc1", 1);
   request.onerror = function() {
     throw new Error("error opening db connection");
   };
-  let db = await new Promise(done => {
+  let db = yield new Promise(done => {
     request.onupgradeneeded = event => {
       let db = event.target.result;
       let store1 = db.createObjectStore("obj-s1uc1", { keyPath: "id" });
@@ -28,7 +28,7 @@ let idbGenerator = async function () {
       };
     };
   });
-  await new Promise(done => {
+  yield new Promise(done => {
     request.onsuccess = done;
   });
 
@@ -36,14 +36,14 @@ let idbGenerator = async function () {
   let store1 = transaction.objectStore("obj-s1uc1");
   store1.add({id: 6, name: "foo", email: "foo@bar.com"});
   store1.add({id: 7, name: "foo2", email: "foo2@bar.com"});
-  await new Promise(success => {
+  yield new Promise(success => {
     transaction.oncomplete = success;
   });
 
   db.close();
 
   request = indexedDB.open("idb-s2uc1", 1);
-  let db2 = await new Promise(done => {
+  let db2 = yield new Promise(done => {
     request.onupgradeneeded = event => {
       let db2 = event.target.result;
       let store3 =
@@ -54,14 +54,14 @@ let idbGenerator = async function () {
       };
     };
   });
-  await new Promise(done => {
+  yield new Promise(done => {
     request.onsuccess = done;
   });
 
   transaction = db2.transaction(["obj-s2uc1"], "readwrite");
   let store3 = transaction.objectStore("obj-s2uc1");
   store3.add({id3: 16, name2: "foo", email: "foo@bar.com"});
-  await new Promise(success => {
+  yield new Promise(success => {
     transaction.oncomplete = success;
   });
 
@@ -76,13 +76,13 @@ function deleteDB(dbName) {
   });
 }
 
-window.setup = async function () {
-  await idbGenerator();
+window.setup = function*() {
+  yield idbGenerator();
 };
 
-window.clear = async function () {
-  await deleteDB("idb-s1uc1");
-  await deleteDB("idb-s2uc1");
+window.clear = function*() {
+  yield deleteDB("idb-s1uc1");
+  yield deleteDB("idb-s2uc1");
 
   dump("removed indexedDB data from " + document.location + "\n");
 };
diff --git a/devtools/client/storage/test/storage-secured-iframe.html b/devtools/client/storage/test/storage-secured-iframe.html
index a4766b8dc8a1..ea830847ab37 100644
--- a/devtools/client/storage/test/storage-secured-iframe.html
+++ b/devtools/client/storage/test/storage-secured-iframe.html
@@ -1,4 +1,4 @@
-<!DOCTYPE HTML>
+<!DOCTYPE HTML>
 <html>
 <!--
 Iframe for testing multiple host detetion in storage actor
@@ -17,12 +17,12 @@ localStorage.setItem("iframe-s-ls1", "foobar");
 sessionStorage.setItem("iframe-s-ss1", "foobar-2");
 dump("added cookies and storage from secured iframe\n");
 
-let idbGenerator = async function () {
+let idbGenerator = function*() {
   let request = indexedDB.open("idb-s1", 1);
   request.onerror = function() {
     throw new Error("error opening db connection");
   };
-  let db = await new Promise(done => {
+  let db = yield new Promise(done => {
     request.onupgradeneeded = event => {
       let db = event.target.result;
       let store1 = db.createObjectStore("obj-s1", { keyPath: "id" });
@@ -31,7 +31,7 @@ let idbGenerator = async function () {
       };
     };
   });
-  await new Promise(done => {
+  yield new Promise(done => {
     request.onsuccess = done;
   });
 
@@ -39,14 +39,14 @@ let idbGenerator = async function () {
   let store1 = transaction.objectStore("obj-s1");
   store1.add({id: 6, name: "foo", email: "foo@bar.com"});
   store1.add({id: 7, name: "foo2", email: "foo2@bar.com"});
-  await new Promise(success => {
+  yield new Promise(success => {
     transaction.oncomplete = success;
   });
 
   db.close();
 
   request = indexedDB.open("idb-s2", 1);
-  let db2 = await new Promise(done => {
+  let db2 = yield new Promise(done => {
     request.onupgradeneeded = event => {
       let db2 = event.target.result;
       let store3 =
@@ -57,14 +57,14 @@ let idbGenerator = async function () {
       };
     };
   });
-  await new Promise(done => {
+  yield new Promise(done => {
     request.onsuccess = done;
   });
 
   transaction = db2.transaction(["obj-s2"], "readwrite");
   let store3 = transaction.objectStore("obj-s2");
   store3.add({id3: 16, name2: "foo", email: "foo@bar.com"});
-  await new Promise(success => {
+  yield new Promise(success => {
     transaction.oncomplete = success;
   });
 
@@ -79,13 +79,13 @@ function deleteDB(dbName) {
   });
 }
 
-window.setup = async function () {
-  await idbGenerator();
+window.setup = function*() {
+  yield idbGenerator();
 };
 
-window.clear = async function () {
-  await deleteDB("idb-s1");
-  await deleteDB("idb-s2");
+window.clear = function*() {
+  yield deleteDB("idb-s1");
+  yield deleteDB("idb-s2");
 
   dump("removed indexedDB data from " + document.location + "\n");
 };
diff --git a/devtools/client/styleeditor/StyleEditorUI.jsm b/devtools/client/styleeditor/StyleEditorUI.jsm
index 6dc9c5d3066b..77ffa39dd944 100644
--- a/devtools/client/styleeditor/StyleEditorUI.jsm
+++ b/devtools/client/styleeditor/StyleEditorUI.jsm
@@ -11,6 +11,7 @@ const {loader, require} = ChromeUtils.import("resource://devtools/shared/Loader.
 const Services = require("Services");
 const {NetUtil} = require("resource://gre/modules/NetUtil.jsm");
 const {OS} = require("resource://gre/modules/osfile.jsm");
+const {Task} = require("devtools/shared/task");
 const EventEmitter = require("devtools/shared/old-event-emitter");
 const {gDevTools} = require("devtools/client/framework/devtools");
 const {
@@ -110,28 +111,28 @@ StyleEditorUI.prototype = {
    * Initiates the style editor ui creation, the inspector front to get
    * reference to the walker and the selector highlighter if available
    */
-  async initialize() {
-    await this.initializeHighlighter();
+  initialize: Task.async(function* () {
+    yield this.initializeHighlighter();
 
     this.createUI();
 
-    let styleSheets = await this._debuggee.getStyleSheets();
-    await this._resetStyleSheetList(styleSheets);
+    let styleSheets = yield this._debuggee.getStyleSheets();
+    yield this._resetStyleSheetList(styleSheets);
 
     this._target.on("will-navigate", this._clear);
     this._target.on("navigate", this._onNewDocument);
-  },
+  }),
 
-  async initializeHighlighter() {
+  initializeHighlighter: Task.async(function* () {
     let toolbox = gDevTools.getToolbox(this._target);
-    await toolbox.initInspector();
+    yield toolbox.initInspector();
     this._walker = toolbox.walker;
 
     let hUtils = toolbox.highlighterUtils;
     if (hUtils.supportsCustomHighlighters()) {
       try {
         this._highlighter =
-          await hUtils.getHighlighterByType(SELECTOR_HIGHLIGHTER_TYPE);
+          yield hUtils.getHighlighterByType(SELECTOR_HIGHLIGHTER_TYPE);
       } catch (e) {
         // The selectorHighlighter can't always be instantiated, for example
         // it doesn't work with XUL windows (until bug 1094959 gets fixed);
@@ -140,7 +141,7 @@ StyleEditorUI.prototype = {
           "elements matching hovered selectors will not be highlighted");
       }
     }
-  },
+  }),
 
   /**
    * Build the initial UI and wire buttons with event handlers.
@@ -231,13 +232,13 @@ StyleEditorUI.prototype = {
    * @param  {array} styleSheets
    *         Array of StyleSheetFront
    */
-  async _resetStyleSheetList(styleSheets) {
+  _resetStyleSheetList: Task.async(function* (styleSheets) {
     this._clear();
     this._suppressAdd = false;
 
     for (let sheet of styleSheets) {
       try {
-        await this._addStyleSheet(sheet);
+        yield this._addStyleSheet(sheet);
       } catch (e) {
         console.error(e);
         this.emit("error", { key: LOAD_ERROR, level: "warning" });
@@ -247,7 +248,7 @@ StyleEditorUI.prototype = {
     this._root.classList.remove("loading");
 
     this.emit("stylesheets-reset");
-  },
+  }),
 
   /**
    * Remove all editors and add loading indicator.
@@ -357,7 +358,7 @@ StyleEditorUI.prototype = {
    * @return {Promise} that is resolved with the created StyleSheetEditor when
    *                   the editor is fully initialized or rejected on error.
    */
-  async _addStyleSheetEditor(styleSheet, isNew) {
+  _addStyleSheetEditor: Task.async(function* (styleSheet, isNew) {
     // recall location of saved file for this sheet after page reload
     let file = null;
     let identifier = this.getStyleSheetIdentifier(styleSheet);
@@ -377,11 +378,11 @@ StyleEditorUI.prototype = {
 
     this.editors.push(editor);
 
-    await editor.fetchSource();
+    yield editor.fetchSource();
     this._sourceLoaded(editor);
 
     return editor;
-  },
+  }),
 
   /**
    * Import a style sheet from file and asynchronously create a
@@ -625,12 +626,12 @@ StyleEditorUI.prototype = {
         let showEditor = data.editor;
         this.selectedEditor = showEditor;
 
-        (async function () {
+        Task.spawn(function* () {
           if (!showEditor.sourceEditor) {
             // only initialize source editor when we switch to this view
             let inputElement =
                 details.querySelector(".stylesheet-editor-input");
-            await showEditor.load(inputElement, this._cssProperties);
+            yield showEditor.load(inputElement, this._cssProperties);
           }
 
           showEditor.onShow();
@@ -638,13 +639,13 @@ StyleEditorUI.prototype = {
           this.emit("editor-selected", showEditor);
 
           // Is there any CSS coverage markup to include?
-          let usage = await csscoverage.getUsage(this._target);
+          let usage = yield csscoverage.getUsage(this._target);
           if (usage == null) {
             return;
           }
 
           let sheet = showEditor.styleSheet;
-          let {reports} = await usage.createEditorReportForSheet(sheet);
+          let {reports} = yield usage.createEditorReportForSheet(sheet);
 
           showEditor.removeAllUnusedRegions();
 
@@ -660,7 +661,7 @@ StyleEditorUI.prototype = {
               this.emit("error", { key: "error-compressed", level: "info" });
             }
           }
-        }.bind(this))().catch(console.error);
+        }.bind(this)).catch(console.error);
       }
     });
   },
@@ -882,8 +883,8 @@ StyleEditorUI.prototype = {
    *         Editor to update @media sidebar of
    */
   _updateMediaList: function (editor) {
-    (async function () {
-      let details = await this.getEditorDetails(editor);
+    Task.spawn(function* () {
+      let details = yield this.getEditorDetails(editor);
       let list = details.querySelector(".stylesheet-media-list");
 
       while (list.firstChild) {
@@ -907,7 +908,7 @@ StyleEditorUI.prototype = {
         };
         if (editor.styleSheet.isOriginalSource) {
           let styleSheet = editor.cssSheet;
-          location = await editor.styleSheet.getOriginalLocation(styleSheet, line,
+          location = yield editor.styleSheet.getOriginalLocation(styleSheet, line,
                                                                  column);
         }
 
@@ -947,7 +948,7 @@ StyleEditorUI.prototype = {
       sidebar.hidden = !showSidebar || !inSource;
 
       this.emit("media-list-changed", editor);
-    }.bind(this))().catch(console.error);
+    }.bind(this)).catch(console.error);
   },
 
   /**
@@ -1011,13 +1012,13 @@ StyleEditorUI.prototype = {
    * @param  {object} options
    *         Object with width or/and height properties.
    */
-  async _launchResponsiveMode(options = {}) {
+  _launchResponsiveMode: Task.async(function* (options = {}) {
     let tab = this._target.tab;
     let win = this._target.tab.ownerDocument.defaultView;
 
-    await ResponsiveUIManager.openIfNeeded(win, tab);
+    yield ResponsiveUIManager.openIfNeeded(win, tab);
     ResponsiveUIManager.getResponsiveUIForTab(tab).setViewportSize(options);
-  },
+  }),
 
   /**
    * Jump cursor to the editor for a stylesheet and line number for a rule.
diff --git a/devtools/client/styleeditor/StyleSheetEditor.jsm b/devtools/client/styleeditor/StyleSheetEditor.jsm
index e74a1e8fde89..3b67b11e9fc7 100644
--- a/devtools/client/styleeditor/StyleSheetEditor.jsm
+++ b/devtools/client/styleeditor/StyleSheetEditor.jsm
@@ -13,6 +13,7 @@ const promise = require("promise");
 const {shortSource, prettifyCSS} = require("devtools/shared/inspector/css-logic");
 const Services = require("Services");
 const EventEmitter = require("devtools/shared/old-event-emitter");
+const {Task} = require("devtools/shared/task");
 const {FileUtils} = require("resource://gre/modules/FileUtils.jsm");
 const {NetUtil} = require("resource://gre/modules/NetUtil.jsm");
 const {OS} = ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
@@ -587,7 +588,7 @@ StyleSheetEditor.prototype = {
    * @param {Number} x
    * @param {Number} y
    */
-  async _highlightSelectorAt(x, y) {
+  _highlightSelectorAt: Task.async(function* (x, y) {
     let pos = this.sourceEditor.getPositionFromCoords({left: x, top: y});
     let info = this.sourceEditor.getInfoAt(pos);
     if (!info || info.state !== "selector") {
@@ -595,8 +596,8 @@ StyleSheetEditor.prototype = {
     }
 
     let node =
-        await this.walker.getStyleSheetOwnerNode(this.styleSheet.actorID);
-    await this.highlighter.show(node, {
+        yield this.walker.getStyleSheetOwnerNode(this.styleSheet.actorID);
+    yield this.highlighter.show(node, {
       selector: info.selector,
       hideInfoBar: true,
       showOnly: "border",
@@ -604,7 +605,7 @@ StyleSheetEditor.prototype = {
     });
 
     this.emit("node-highlighted");
-  },
+  }),
 
   /**
    * Save the editor contents into a file and set savedFile property.
diff --git a/devtools/client/styleeditor/styleeditor-panel.js b/devtools/client/styleeditor/styleeditor-panel.js
index 59c338d96c4f..c82fb3dc3daf 100644
--- a/devtools/client/styleeditor/styleeditor-panel.js
+++ b/devtools/client/styleeditor/styleeditor-panel.js
@@ -6,6 +6,7 @@
 
 var Services = require("Services");
 var promise = require("promise");
+var {Task} = require("devtools/shared/task");
 var {XPCOMUtils} = require("resource://gre/modules/XPCOMUtils.jsm");
 var EventEmitter = require("devtools/shared/old-event-emitter");
 
@@ -39,10 +40,10 @@ StyleEditorPanel.prototype = {
   /**
    * open is effectively an asynchronous constructor
    */
-  async open() {
+  open: Task.async(function* () {
     // We always interact with the target as if it were remote
     if (!this.target.isRemote) {
-      await this.target.makeRemote();
+      yield this.target.makeRemote();
     }
 
     this.target.on("close", this.destroy);
@@ -50,18 +51,18 @@ StyleEditorPanel.prototype = {
     this._debuggee = this._toolbox.initStyleSheetsFront();
 
     // Initialize the CSS properties database.
-    const {cssProperties} = await initCssProperties(this._toolbox);
+    const {cssProperties} = yield initCssProperties(this._toolbox);
 
     // Initialize the UI
     this.UI = new StyleEditorUI(this._debuggee, this.target, this._panelDoc,
                                 cssProperties);
     this.UI.on("error", this._showError);
-    await this.UI.initialize();
+    yield this.UI.initialize();
 
     this.isReady = true;
 
     return this;
-  },
+  }),
 
   /**
    * Show an error message from the style editor in the toolbox
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_add_stylesheet.js b/devtools/client/styleeditor/test/browser_styleeditor_add_stylesheet.js
index e77780a0e4d0..d8315d212920 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_add_stylesheet.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_add_stylesheet.js
@@ -7,8 +7,8 @@
 
 const TESTCASE_URI = TEST_BASE_HTTPS + "simple.html";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "Two sheets present after load.");
 
@@ -25,13 +25,13 @@ add_task(async function () {
   });
 
   info("Adding a style sheet");
-  await ContentTask.spawn(gBrowser.selectedBrowser, null, () => {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, null, () => {
     let document = content.document;
     const style = document.createElement("style");
     style.appendChild(document.createTextNode("div { background: #f06; }"));
     document.head.appendChild(style);
   });
-  await added;
+  yield added;
 
   is(ui.editors.length, 3, "Three sheets present after new style sheet");
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_autocomplete-disabled.js b/devtools/client/styleeditor/test/browser_styleeditor_autocomplete-disabled.js
index 1fb337ae8745..b632a7716006 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_autocomplete-disabled.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_autocomplete-disabled.js
@@ -10,10 +10,10 @@ const TESTCASE_URI = TEST_BASE_HTTP + "autocomplete.html";
 // Pref which decides if CSS autocompletion is enabled in Style Editor or not.
 const AUTOCOMPLETION_PREF = "devtools.styleeditor.autocompletion-enabled";
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setBoolPref(AUTOCOMPLETION_PREF, false);
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
-  let editor = await ui.editors[0].getSourceEditor();
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
+  let editor = yield ui.editors[0].getSourceEditor();
 
   is(editor.sourceEditor.getOption("autocomplete"), false,
      "Autocompletion option does not exist");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_autocomplete.js b/devtools/client/styleeditor/test/browser_styleeditor_autocomplete.js
index 03f44ba00bfb..8b78c400c2f4 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_autocomplete.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_autocomplete.js
@@ -105,22 +105,22 @@ function getTestCases(cssProperties) {
   ];
 }
 
-add_task(async function () {
-  let { panel, ui } = await openStyleEditorForURL(TESTCASE_URI);
-  let { cssProperties } = await initCssProperties(panel._toolbox);
+add_task(function* () {
+  let { panel, ui } = yield openStyleEditorForURL(TESTCASE_URI);
+  let { cssProperties } = yield initCssProperties(panel._toolbox);
   let testCases = getTestCases(cssProperties);
 
-  await ui.selectStyleSheet(ui.editors[1].styleSheet);
-  let editor = await ui.editors[1].getSourceEditor();
+  yield ui.selectStyleSheet(ui.editors[1].styleSheet);
+  let editor = yield ui.editors[1].getSourceEditor();
 
   let sourceEditor = editor.sourceEditor;
   let popup = sourceEditor.getAutocompletionPopup();
 
-  await SimpleTest.promiseFocus(panel.panelWindow);
+  yield SimpleTest.promiseFocus(panel.panelWindow);
 
   for (let index in testCases) {
-    await testState(testCases, index, sourceEditor, popup, panel.panelWindow);
-    await checkState(testCases, index, sourceEditor, popup);
+    yield testState(testCases, index, sourceEditor, popup, panel.panelWindow);
+    yield checkState(testCases, index, sourceEditor, popup);
   }
 });
 
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_bom.js b/devtools/client/styleeditor/test/browser_styleeditor_bom.js
index 95dfb5f69cfc..56275a3a9580 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_bom.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_bom.js
@@ -21,13 +21,13 @@ const DOCUMENT = "data:text/html;charset=UTF-8," +
 const CONTENTS = "// Note that this file must be utf-16 with a " +
       "BOM for the test to make sense.\n";
 
-add_task(async function () {
-  let {ui} = await openStyleEditorForURL(DOCUMENT);
+add_task(function* () {
+  let {ui} = yield openStyleEditorForURL(DOCUMENT);
 
   is(ui.editors.length, 1, "correct number of editors");
 
   let editor = ui.editors[0];
-  await editor.getSourceEditor();
+  yield editor.getSourceEditor();
 
   let text = editor.sourceEditor.getText();
   is(text, CONTENTS, "editor contains expected text");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_bug_740541_iframes.js b/devtools/client/styleeditor/test/browser_styleeditor_bug_740541_iframes.js
index 8eb7f989e36b..3b9235a9b0f8 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_bug_740541_iframes.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_bug_740541_iframes.js
@@ -4,7 +4,7 @@
 
 // Test that sheets inside iframes are shown in the editor.
 
-add_task(async function () {
+add_task(function* () {
   function makeStylesheet(selector) {
     return ("data:text/css;charset=UTF-8," +
             encodeURIComponent(selector + " { }"));
@@ -68,7 +68,7 @@ add_task(async function () {
 
   const EXPECTED_STYLE_SHEET_COUNT = 12;
 
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, EXPECTED_STYLE_SHEET_COUNT,
     "Got the expected number of style sheets.");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_bug_851132_middle_click.js b/devtools/client/styleeditor/test/browser_styleeditor_bug_851132_middle_click.js
index 48a182cf8171..95b502dc259e 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_bug_851132_middle_click.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_bug_851132_middle_click.js
@@ -7,25 +7,25 @@
 
 const TESTCASE_URI = TEST_BASE_HTTP + "four.html";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
   gBrowser.tabContainer.addEventListener("TabOpen", onTabAdded);
 
-  await ui.editors[0].getSourceEditor();
+  yield ui.editors[0].getSourceEditor();
   info("first editor selected");
 
   info("Left-clicking on the second editor link.");
-  await clickOnStyleSheetLink(ui.editors[1], 0);
+  yield clickOnStyleSheetLink(ui.editors[1], 0);
 
   info("Waiting for the second editor to be selected.");
-  let editor = await ui.once("editor-selected");
+  let editor = yield ui.once("editor-selected");
 
   ok(editor.sourceEditor.hasFocus(),
      "Left mouse click gave second editor focus.");
 
   // middle mouse click should not open a new tab
   info("Middle clicking on the third editor link.");
-  await clickOnStyleSheetLink(ui.editors[2], 1);
+  yield clickOnStyleSheetLink(ui.editors[2], 1);
 });
 
 /**
@@ -36,12 +36,12 @@ add_task(async function () {
  * @param {MouseEvent.button} button
  *        The button to click the link with.
  */
-async function clickOnStyleSheetLink(editor, button) {
+function* clickOnStyleSheetLink(editor, button) {
   let window = editor._window;
   let link = editor.summary.querySelector(".stylesheet-name");
 
   info("Waiting for focus.");
-  await SimpleTest.promiseFocus(window);
+  yield SimpleTest.promiseFocus(window);
 
   info("Pressing button " + button + " on style sheet name link.");
   EventUtils.synthesizeMouseAtCenter(link, { button }, window);
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_bug_870339.js b/devtools/client/styleeditor/test/browser_styleeditor_bug_870339.js
index 12317967f263..9b0b7b3f4417 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_bug_870339.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_bug_870339.js
@@ -16,8 +16,8 @@ const DOCUMENT_WITH_ONE_STYLESHEET = "data:text/html;charset=UTF-8," +
            "</html>"
           ].join("\n"));
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(DOCUMENT_WITH_ONE_STYLESHEET);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(DOCUMENT_WITH_ONE_STYLESHEET);
 
   // Spam the _onNewDocument callback multiple times before the
   // StyleEditorActor has a chance to respond to the first one.
@@ -28,7 +28,7 @@ add_task(async function () {
 
   // Wait for the StyleEditorActor to respond to each "newDocument"
   // message.
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     let loadCount = 0;
     ui.on("stylesheets-reset", function onReset() {
       ++loadCount;
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_cmd_edit.js b/devtools/client/styleeditor/test/browser_styleeditor_cmd_edit.js
index 6d225f6cf36f..96b64cc9476d 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_cmd_edit.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_cmd_edit.js
@@ -14,11 +14,11 @@ Services.scriptloader.loadSubScript(
 const TEST_URI = "http://example.com/browser/devtools/client/styleeditor/" +
                  "test/browser_styleeditor_cmd_edit.html";
 
-add_task(async function () {
-  let options = await helpers.openTab(TEST_URI);
-  await helpers.openToolbar(options);
+add_task(function* () {
+  let options = yield helpers.openTab(TEST_URI);
+  yield helpers.openToolbar(options);
 
-  await helpers.audit(options, [
+  yield helpers.audit(options, [
     {
       setup: "edit",
       check: {
@@ -192,7 +192,7 @@ add_task(async function () {
   let toolbox = gDevTools.getToolbox(options.target);
   ok(toolbox == null, "toolbox is closed");
 
-  await helpers.audit(options, [
+  yield helpers.audit(options, [
     {
       setup: "edit css#style2",
       check: {
@@ -208,8 +208,8 @@ add_task(async function () {
   let styleEditor = toolbox.getCurrentPanel();
   ok(typeof styleEditor.selectStyleSheet === "function", "styleeditor is open");
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
 
-  await helpers.closeToolbar(options);
-  await helpers.closeTab(options);
+  yield helpers.closeToolbar(options);
+  yield helpers.closeTab(options);
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_enabled.js b/devtools/client/styleeditor/test/browser_styleeditor_enabled.js
index 5a945a4b2302..993225de00ca 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_enabled.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_enabled.js
@@ -8,9 +8,9 @@
 // https rather than chrome to improve coverage
 const TESTCASE_URI = TEST_BASE_HTTPS + "simple.html";
 
-add_task(async function () {
-  let { panel, ui } = await openStyleEditorForURL(TESTCASE_URI);
-  let editor = await ui.editors[0].getSourceEditor();
+add_task(function* () {
+  let { panel, ui } = yield openStyleEditorForURL(TESTCASE_URI);
+  let editor = yield ui.editors[0].getSourceEditor();
 
   let summary = editor.summary;
   let enabledToggle = summary.querySelector(".stylesheet-enabled");
@@ -23,14 +23,14 @@ add_task(async function () {
      "first stylesheet is initially enabled, UI does not have DISABLED class");
 
   info("Disabling the first stylesheet.");
-  await toggleEnabled(editor, enabledToggle, panel.panelWindow);
+  yield toggleEnabled(editor, enabledToggle, panel.panelWindow);
 
   is(editor.styleSheet.disabled, true, "first stylesheet is now disabled");
   is(summary.classList.contains("disabled"), true,
      "first stylesheet is now disabled, UI has DISABLED class");
 
   info("Enabling the first stylesheet again.");
-  await toggleEnabled(editor, enabledToggle, panel.panelWindow);
+  yield toggleEnabled(editor, enabledToggle, panel.panelWindow);
 
   is(editor.styleSheet.disabled, false,
      "first stylesheet is now enabled again");
@@ -38,19 +38,19 @@ add_task(async function () {
      "first stylesheet is now enabled again, UI does not have DISABLED class");
 });
 
-async function toggleEnabled(editor, enabledToggle, panelWindow) {
+function* toggleEnabled(editor, enabledToggle, panelWindow) {
   let changed = editor.once("property-change");
 
   info("Waiting for focus.");
-  await SimpleTest.promiseFocus(panelWindow);
+  yield SimpleTest.promiseFocus(panelWindow);
 
   info("Clicking on the toggle.");
   EventUtils.synthesizeMouseAtCenter(enabledToggle, {}, panelWindow);
 
   info("Waiting for stylesheet to be disabled.");
-  let property = await changed;
+  let property = yield changed;
   while (property !== "disabled") {
     info("Ignoring property-change for '" + property + "'.");
-    property = await editor.once("property-change");
+    property = yield editor.once("property-change");
   }
 }
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js b/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
index 2664d521382d..0689e68a45ea 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_fetch-from-netmonitor.js
@@ -8,11 +8,11 @@
 
 const TEST_URL = TEST_BASE_HTTP + "doc_fetch_from_netmonitor.html";
 
-add_task(async function () {
+add_task(function* () {
   info("Opening netmonitor");
-  let tab = await addTab("about:blank");
+  let tab = yield addTab("about:blank");
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "netmonitor");
+  let toolbox = yield gDevTools.showToolbox(target, "netmonitor");
   let monitor = toolbox.getPanel("netmonitor");
   let { store, windowRequire } = monitor.panelWin;
   let Actions = windowRequire("devtools/client/netmonitor/src/actions/index");
@@ -23,16 +23,16 @@ add_task(async function () {
   store.dispatch(Actions.batchEnable(false));
 
   info("Navigating to test page");
-  await navigateTo(TEST_URL);
+  yield navigateTo(TEST_URL);
 
   info("Opening Style Editor");
-  let styleeditor = await toolbox.selectTool("styleeditor");
+  let styleeditor = yield toolbox.selectTool("styleeditor");
   let ui = styleeditor.UI;
 
   info("Waiting for the sources to be loaded.");
-  await ui.editors[0].getSourceEditor();
-  await ui.selectStyleSheet(ui.editors[1].styleSheet);
-  await ui.editors[1].getSourceEditor();
+  yield ui.editors[0].getSourceEditor();
+  yield ui.selectStyleSheet(ui.editors[1].styleSheet);
+  yield ui.editors[1].getSourceEditor();
 
   info("Checking Netmonitor contents.");
   let shortRequests = [];
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_filesave.js b/devtools/client/styleeditor/test/browser_styleeditor_filesave.js
index 9db48ee2cccc..f11985eb3000 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_filesave.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_filesave.js
@@ -14,23 +14,23 @@ ChromeUtils.import("resource://gre/modules/NetUtil.jsm", tempScope);
 var FileUtils = tempScope.FileUtils;
 var NetUtil = tempScope.NetUtil;
 
-add_task(async function () {
-  let htmlFile = await copy(TESTCASE_URI_HTML, "simple.html");
-  await copy(TESTCASE_URI_CSS, "simple.css");
+add_task(function* () {
+  let htmlFile = yield copy(TESTCASE_URI_HTML, "simple.html");
+  yield copy(TESTCASE_URI_CSS, "simple.css");
   let uri = Services.io.newFileURI(htmlFile);
   let filePath = uri.resolve("");
 
-  let { ui } = await openStyleEditorForURL(filePath);
+  let { ui } = yield openStyleEditorForURL(filePath);
 
   let editor = ui.editors[0];
-  await editor.getSourceEditor();
+  yield editor.getSourceEditor();
 
   info("Editing the style sheet.");
   let dirty = editor.sourceEditor.once("dirty-change");
   let beginCursor = {line: 0, ch: 0};
   editor.sourceEditor.replaceText("DIRTY TEXT", beginCursor, beginCursor);
 
-  await dirty;
+  yield dirty;
 
   is(editor.sourceEditor.isClean(), false, "Editor is dirty.");
   ok(editor.summary.classList.contains("unsaved"),
@@ -43,7 +43,7 @@ add_task(async function () {
     ok(file, "file should get saved directly when using a file:// URI");
   });
 
-  await dirty;
+  yield dirty;
 
   is(editor.sourceEditor.isClean(), true, "Editor is clean.");
   ok(!editor.summary.classList.contains("unsaved"),
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_highlight-selector.js b/devtools/client/styleeditor/test/browser_styleeditor_highlight-selector.js
index 13ea3949c9be..ab1dba7a9d5f 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_highlight-selector.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_highlight-selector.js
@@ -7,9 +7,9 @@
 // Test that hovering over a simple selector in the style-editor requests the
 // highlighting of the corresponding nodes
 
-add_task(async function () {
+add_task(function* () {
   let url = TEST_BASE_HTTP + "selector-highlighter.html";
-  let { ui } = await openStyleEditorForURL(url);
+  let { ui } = yield openStyleEditorForURL(url);
   let editor = ui.editors[0];
 
   // Mock the highlighter so we can locally assert that things happened
@@ -34,7 +34,7 @@ add_task(async function () {
 
   info("Simulate a mousemove event on the div selector");
   editor._onMouseMove({clientX: 56, clientY: 10});
-  await onHighlighted;
+  yield onHighlighted;
 
   ok(editor.highlighter.isShown, "The highlighter is now shown");
   is(editor.highlighter.options.selector, "div", "The selector is correct");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_import.js b/devtools/client/styleeditor/test/browser_styleeditor_import.js
index 85c44e234009..0386a4679938 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_import.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_import.js
@@ -15,14 +15,14 @@ var FileUtils = tempScope.FileUtils;
 const FILENAME = "styleeditor-import-test.css";
 const SOURCE = "body{background:red;}";
 
-add_task(async function () {
-  let { panel, ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { panel, ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   let added = ui.once("test:editor-updated");
   importSheet(ui, panel.panelWindow);
 
   info("Waiting for editor to be added for the imported sheet.");
-  let editor = await added;
+  let editor = yield added;
 
   is(editor.savedFile.leafName, FILENAME,
      "imported stylesheet will be saved directly into the same file");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_import_rule.js b/devtools/client/styleeditor/test/browser_styleeditor_import_rule.js
index 31e60c1bc06a..46d0a0968a61 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_import_rule.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_import_rule.js
@@ -8,8 +8,8 @@
 // http rather than chrome to improve coverage
 const TESTCASE_URI = TEST_BASE_HTTP + "import.html";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 3,
     "there are 3 stylesheets after loading @imports");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_init.js b/devtools/client/styleeditor/test/browser_styleeditor_init.js
index 787065c015d7..47a8f1e05f2c 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_init.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_init.js
@@ -20,8 +20,8 @@ const EXPECTED_SHEETS = [
   }
 ];
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "The UI contains two style sheets.");
   checkSheet(ui.editors[0], EXPECTED_SHEETS[0]);
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_inline_friendly_names.js b/devtools/client/styleeditor/test/browser_styleeditor_inline_friendly_names.js
index 72448c3a64f6..acc1bd9c010a 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_inline_friendly_names.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_inline_friendly_names.js
@@ -10,17 +10,17 @@ const FIRST_TEST_PAGE = TEST_BASE_HTTP + "inline-1.html";
 const SECOND_TEST_PAGE = TEST_BASE_HTTP + "inline-2.html";
 const SAVE_PATH = "test.css";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(FIRST_TEST_PAGE);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(FIRST_TEST_PAGE);
 
   testIndentifierGeneration(ui);
 
-  await saveFirstInlineStyleSheet(ui);
-  await testFriendlyNamesAfterSave(ui);
-  await reloadPageAndWaitForStyleSheets(ui);
-  await testFriendlyNamesAfterSave(ui);
-  await navigateToAndWaitForStyleSheets(SECOND_TEST_PAGE, ui);
-  await testFriendlyNamesAfterNavigation(ui);
+  yield saveFirstInlineStyleSheet(ui);
+  yield testFriendlyNamesAfterSave(ui);
+  yield reloadPageAndWaitForStyleSheets(ui);
+  yield testFriendlyNamesAfterSave(ui);
+  yield navigateToAndWaitForStyleSheets(SECOND_TEST_PAGE, ui);
+  yield testFriendlyNamesAfterNavigation(ui);
 });
 
 function testIndentifierGeneration(ui) {
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_loading.js b/devtools/client/styleeditor/test/browser_styleeditor_loading.js
index fd7d9298fd21..4657a0dce955 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_loading.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_loading.js
@@ -7,7 +7,7 @@
 
 const TESTCASE_URI = TEST_BASE_HTTP + "longload.html";
 
-add_task(async function () {
+add_task(function* () {
   // launch Style Editor right when the tab is created (before load)
   // this checks that the Style Editor still launches correctly when it is
   // opened *while* the page is still loading. The Style Editor should not
@@ -16,7 +16,7 @@ add_task(async function () {
   let target = TargetFactory.forTab(gBrowser.selectedTab);
   let styleEditorLoaded = gDevTools.showToolbox(target, "styleeditor");
 
-  await Promise.all([tabAdded, styleEditorLoaded]);
+  yield Promise.all([tabAdded, styleEditorLoaded]);
 
   let toolbox = gDevTools.getToolbox(target);
   let panel = toolbox.getPanel("styleeditor");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_loading_with_containers.js b/devtools/client/styleeditor/test/browser_styleeditor_loading_with_containers.js
index 67dd1de7084f..cfe7c3be701a 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_loading_with_containers.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_loading_with_containers.js
@@ -22,18 +22,18 @@ const EXPECTED_SHEETS = [
   }
 ];
 
-add_task(async function () {
+add_task(function* () {
   // Using the personal container.
   let userContextId = 1;
-  let { tab } = await openTabInUserContext(TESTCASE_URI, userContextId);
-  let { ui } = await openStyleEditor(tab);
+  let { tab } = yield* openTabInUserContext(TESTCASE_URI, userContextId);
+  let { ui } = yield openStyleEditor(tab);
 
   is(ui.editors.length, 2, "The UI contains two style sheets.");
   checkSheet(ui.editors[0], EXPECTED_SHEETS[0]);
   checkSheet(ui.editors[1], EXPECTED_SHEETS[1]);
 });
 
-async function openTabInUserContext(uri, userContextId) {
+function* openTabInUserContext(uri, userContextId) {
   // Open the tab in the correct userContextId.
   let tab = BrowserTestUtils.addTab(gBrowser, uri, {userContextId});
 
@@ -42,7 +42,7 @@ async function openTabInUserContext(uri, userContextId) {
   tab.ownerDocument.defaultView.focus();
 
   let browser = gBrowser.getBrowserForTab(tab);
-  await BrowserTestUtils.browserLoaded(browser);
+  yield BrowserTestUtils.browserLoaded(browser);
   return {tab, browser};
 }
 
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar.js b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar.js
index 99b32295eb8a..ab571504b1ad 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar.js
@@ -17,26 +17,26 @@ const NEW_RULE = "\n@media (max-width: 600px) { div { color: blue; } }";
 
 waitForExplicitFinish();
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "correct number of editors");
 
   // Test first plain css editor
   let plainEditor = ui.editors[0];
-  await openEditor(plainEditor);
+  yield openEditor(plainEditor);
   testPlainEditor(plainEditor);
 
   // Test editor with @media rules
   let mediaEditor = ui.editors[1];
-  await openEditor(mediaEditor);
+  yield openEditor(mediaEditor);
   testMediaEditor(mediaEditor);
 
   // Test that sidebar hides when flipping pref
-  await testShowHide(ui, mediaEditor);
+  yield testShowHide(ui, mediaEditor);
 
   // Test adding a rule updates the list
-  await testMediaRuleAdded(ui, mediaEditor);
+  yield testMediaRuleAdded(ui, mediaEditor);
 
   // Test resizing and seeing @media matching state change
   let originalWidth = window.outerWidth;
@@ -44,7 +44,7 @@ add_task(async function () {
 
   let onMatchesChange = listenForMediaChange(ui);
   window.resizeTo(RESIZE, RESIZE);
-  await onMatchesChange;
+  yield onMatchesChange;
 
   testMediaMatchChanged(mediaEditor);
 
@@ -79,29 +79,29 @@ function testMediaMatchChanged(editor) {
      "media rule is now matched after resizing");
 }
 
-async function testShowHide(UI, editor) {
+function* testShowHide(UI, editor) {
   let sidebarChange = listenForMediaChange(UI);
   Services.prefs.setBoolPref(MEDIA_PREF, false);
-  await sidebarChange;
+  yield sidebarChange;
 
   let sidebar = editor.details.querySelector(".stylesheet-sidebar");
   is(sidebar.hidden, true, "sidebar is hidden after flipping pref");
 
   sidebarChange = listenForMediaChange(UI);
   Services.prefs.clearUserPref(MEDIA_PREF);
-  await sidebarChange;
+  yield sidebarChange;
 
   is(sidebar.hidden, false, "sidebar is showing after flipping pref back");
 }
 
-async function testMediaRuleAdded(UI, editor) {
-  await editor.getSourceEditor();
+function* testMediaRuleAdded(UI, editor) {
+  yield editor.getSourceEditor();
   let text = editor.sourceEditor.getText();
   text += NEW_RULE;
 
   let listChange = listenForMediaChange(UI);
   editor.sourceEditor.setText(text);
-  await listChange;
+  yield listChange;
 
   let sidebar = editor.details.querySelector(".stylesheet-sidebar");
   let entries = [...sidebar.querySelectorAll(".media-rule-label")];
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_links.js b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_links.js
index 2f63579d9d81..a198be3dbf16 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_links.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_links.js
@@ -21,18 +21,18 @@ loader.lazyRequireGetter(this, "ResponsiveUIManager", "devtools/client/responsiv
 const TESTCASE_URI = TEST_BASE_HTTPS + "media-rules.html";
 const responsiveModeToggleClass = ".media-responsive-mode-toggle";
 
-add_task(async function () {
-  let {ui} = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let {ui} = yield openStyleEditorForURL(TESTCASE_URI);
 
   let editor = ui.editors[1];
-  await openEditor(editor);
+  yield openEditor(editor);
 
   let tab = gBrowser.selectedTab;
   testNumberOfLinks(editor);
-  await testMediaLink(editor, tab, ui, 2, "width", 400);
-  await testMediaLink(editor, tab, ui, 3, "height", 300);
+  yield testMediaLink(editor, tab, ui, 2, "width", 400);
+  yield testMediaLink(editor, tab, ui, 3, "height", 300);
 
-  await closeRDM(tab, ui);
+  yield closeRDM(tab, ui);
   doFinalChecks(editor);
 });
 
@@ -51,7 +51,7 @@ function testNumberOfLinks(editor) {
        "There should be 2 responsive mode links in the media rule");
 }
 
-async function testMediaLink(editor, tab, ui, itemIndex, type, value) {
+function* testMediaLink(editor, tab, ui, itemIndex, type, value) {
   let sidebar = editor.details.querySelector(".stylesheet-sidebar");
   let conditions = sidebar.querySelectorAll(".media-rule-condition");
 
@@ -65,8 +65,8 @@ async function testMediaLink(editor, tab, ui, itemIndex, type, value) {
   rdmUI.transitionsEnabled = false;
 
   info("Waiting for the @media list to update");
-  await onMediaChange;
-  await onContentResize;
+  yield onMediaChange;
+  yield onContentResize;
 
   ok(ResponsiveUIManager.isActiveForTab(tab),
     "Responsive mode should be active.");
@@ -74,16 +74,16 @@ async function testMediaLink(editor, tab, ui, itemIndex, type, value) {
   ok(!conditions[itemIndex].classList.contains("media-condition-unmatched"),
      "media rule should now be matched after responsive mode is active");
 
-  let dimension = (await getSizing(rdmUI))[type];
+  let dimension = (yield getSizing(rdmUI))[type];
   is(dimension, value, `${type} should be properly set.`);
 }
 
-async function closeRDM(tab, ui) {
+function* closeRDM(tab, ui) {
   info("Closing responsive mode");
   ResponsiveUIManager.toggle(window, tab);
   let onMediaChange = waitForNEvents(ui, "media-list-changed", 2);
-  await once(ResponsiveUIManager, "off");
-  await onMediaChange;
+  yield once(ResponsiveUIManager, "off");
+  yield onMediaChange;
   ok(!ResponsiveUIManager.isActiveForTab(tab),
      "Responsive mode should no longer be active.");
 }
@@ -114,9 +114,9 @@ function waitForResizeTo(rdmUI, type, value) {
   });
 }
 
-async function getSizing(rdmUI) {
+function* getSizing(rdmUI) {
   let browser = rdmUI.getViewportBrowser();
-  let sizing = await ContentTask.spawn(browser, {}, async function () {
+  let sizing = yield ContentTask.spawn(browser, {}, function* () {
     return {
       width: content.innerWidth,
       height: content.innerHeight
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_sourcemaps.js b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_sourcemaps.js
index 4e2285ae6a64..45b83005d584 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_sourcemaps.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_media_sidebar_sourcemaps.js
@@ -14,16 +14,16 @@ const LINE_NOS = [5, 8];
 
 waitForExplicitFinish();
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setBoolPref(MAP_PREF, true);
 
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 1, "correct number of editors");
 
   // Test editor with @media rules
   let mediaEditor = ui.editors[0];
-  await openEditor(mediaEditor);
+  yield openEditor(mediaEditor);
   testMediaEditor(mediaEditor);
 
   Services.prefs.clearUserPref(MAP_PREF);
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_missing_stylesheet.js b/devtools/client/styleeditor/test/browser_styleeditor_missing_stylesheet.js
index 04a02d110bb1..ccf98c161b6f 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_missing_stylesheet.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_missing_stylesheet.js
@@ -8,8 +8,8 @@
 
 const TESTCASE_URI = TEST_BASE + "missing.html";
 
-add_task(async function () {
-  let { ui, toolbox, panel } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui, toolbox, panel } = yield openStyleEditorForURL(TESTCASE_URI);
 
   // Note that we're not testing for a specific number of stylesheet editors
   // below because the test-page is loaded with chrome:// URL and, right now,
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_navigate.js b/devtools/client/styleeditor/test/browser_styleeditor_navigate.js
index eec2629a3c47..4d44fca70a84 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_navigate.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_navigate.js
@@ -11,18 +11,18 @@ const NEW_URI = TEST_BASE_HTTPS + "media.html";
 const LINE_NO = 5;
 const COL_NO = 3;
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "Two sheets present after load.");
 
   info("Selecting the second editor");
-  await ui.selectStyleSheet(ui.editors[1].styleSheet, LINE_NO, COL_NO);
+  yield ui.selectStyleSheet(ui.editors[1].styleSheet, LINE_NO, COL_NO);
 
-  await navigateToAndWaitForStyleSheets(NEW_URI, ui);
+  yield navigateToAndWaitForStyleSheets(NEW_URI, ui);
 
   info("Waiting for source editor to be ready.");
-  await ui.editors[0].getSourceEditor();
+  yield ui.editors[0].getSourceEditor();
 
   is(ui.selectedEditor, ui.editors[0], "first editor is selected");
 
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_new.js b/devtools/client/styleeditor/test/browser_styleeditor_new.js
index 440f56882603..8d681496f6ff 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_new.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_new.js
@@ -9,18 +9,18 @@ const TESTCASE_URI = TEST_BASE_HTTP + "simple.html";
 
 const TESTCASE_CSS_SOURCE = "body{background-color:red;";
 
-add_task(async function () {
-  let { panel, ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { panel, ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
-  let editor = await createNew(ui, panel.panelWindow);
-  await testInitialState(editor);
+  let editor = yield createNew(ui, panel.panelWindow);
+  yield testInitialState(editor);
 
   let originalHref = editor.styleSheet.href;
   let waitForPropertyChange = onPropertyChange(editor);
 
-  await typeInEditor(editor, panel.panelWindow);
+  yield typeInEditor(editor, panel.panelWindow);
 
-  await waitForPropertyChange;
+  yield waitForPropertyChange;
 
   testUpdated(editor, originalHref);
 });
@@ -57,7 +57,7 @@ function onPropertyChange(editor) {
   });
 }
 
-async function testInitialState(editor) {
+function* testInitialState(editor) {
   info("Testing the initial state of the new editor");
 
   let summary = editor.summary;
@@ -71,7 +71,7 @@ async function testInitialState(editor) {
   let ruleCount = summary.querySelector(".stylesheet-rule-count").textContent;
   is(parseInt(ruleCount, 10), 0, "new editor initially shows 0 rules");
 
-  let color = await getComputedStyleProperty({
+  let color = yield getComputedStyleProperty({
     selector: "body",
     name: "background-color"
   });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_nostyle.js b/devtools/client/styleeditor/test/browser_styleeditor_nostyle.js
index 4d8844d3c1cf..c01b7c572ec0 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_nostyle.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_nostyle.js
@@ -8,8 +8,8 @@
 
 const TESTCASE_URI = TEST_BASE_HTTP + "nostyle.html";
 
-add_task(async function () {
-  let { panel } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { panel } = yield openStyleEditorForURL(TESTCASE_URI);
   let { panelWindow } = panel;
 
   let root = panelWindow.document.querySelector(".splitview-root");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_opentab.js b/devtools/client/styleeditor/test/browser_styleeditor_opentab.js
index ae8636443308..d52e289c2163 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_opentab.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_opentab.js
@@ -8,10 +8,10 @@
 // context menu item for stylesheets (bug 992947).
 const TESTCASE_URI = TEST_BASE_HTTPS + "simple.html";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
-  await rightClickStyleSheet(ui, ui.editors[0]);
+  yield rightClickStyleSheet(ui, ui.editors[0]);
   is(ui._openLinkNewTabItem.getAttribute("disabled"), "false",
     "The menu item is not disabled");
   is(ui._openLinkNewTabItem.getAttribute("hidden"), "false",
@@ -35,15 +35,15 @@ add_task(async function () {
   ui._openLinkNewTabItem.click();
 
   info(`Waiting for a tab to open - ${url}`);
-  await tabOpenedDefer;
+  yield tabOpenedDefer;
 
-  await rightClickInlineStyleSheet(ui, ui.editors[1]);
+  yield rightClickInlineStyleSheet(ui, ui.editors[1]);
   is(ui._openLinkNewTabItem.getAttribute("disabled"), "true",
     "The menu item is disabled");
   is(ui._openLinkNewTabItem.getAttribute("hidden"), "false",
     "The menu item is not hidden");
 
-  await rightClickNoStyleSheet(ui);
+  yield rightClickNoStyleSheet(ui);
   is(ui._openLinkNewTabItem.getAttribute("hidden"), "true",
     "The menu item is not hidden");
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_pretty.js b/devtools/client/styleeditor/test/browser_styleeditor_pretty.js
index b0426405ed30..62a023e1eedb 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_pretty.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_pretty.js
@@ -48,24 +48,24 @@ const ORIGINAL_SOURCE = "" +
 
 const EXPAND_TAB = "devtools.editor.expandtab";
 
-add_task(async function () {
+add_task(function* () {
   let oldExpandTabPref = SpecialPowers.getBoolPref(EXPAND_TAB);
   // The 'EXPAND_TAB' preference has to be set to false because
   // the constant 'PRETTIFIED_SOURCE' uses tabs for indentation.
   SpecialPowers.setBoolPref(EXPAND_TAB, false);
 
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
   is(ui.editors.length, 2, "Two sheets present.");
 
   info("Testing minified style sheet.");
-  let editor = await ui.editors[0].getSourceEditor();
+  let editor = yield ui.editors[0].getSourceEditor();
 
   let prettifiedSourceRE = new RegExp(PRETTIFIED_SOURCE);
   ok(prettifiedSourceRE.test(editor.sourceEditor.getText()),
      "minified source has been prettified automatically");
 
   info("Selecting second, non-minified style sheet.");
-  await ui.selectStyleSheet(ui.editors[1].styleSheet);
+  yield ui.selectStyleSheet(ui.editors[1].styleSheet);
 
   editor = ui.editors[1];
 
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_private_perwindowpb.js b/devtools/client/styleeditor/test/browser_styleeditor_private_perwindowpb.js
index b855a5c8084c..255b1a2e718e 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_private_perwindowpb.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_private_perwindowpb.js
@@ -10,23 +10,23 @@
 const TEST_URL = "http://" + TEST_HOST + "/browser/devtools/client/" +
   "styleeditor/test/test_private.html";
 
-add_task(async function () {
+add_task(function* () {
   info("Opening a new private window");
   let win = OpenBrowserWindow({private: true});
-  await waitForDelayedStartupFinished(win);
+  yield waitForDelayedStartupFinished(win);
 
   info("Clearing the browser cache");
   Services.cache2.clear();
 
-  let { toolbox, ui } = await openStyleEditorForURL(TEST_URL, win);
+  let { toolbox, ui } = yield openStyleEditorForURL(TEST_URL, win);
 
   is(ui.editors.length, 1, "The style editor contains one sheet.");
   let editor = ui.editors[0];
 
-  await editor.getSourceEditor();
-  await checkDiskCacheFor(TEST_HOST);
+  yield editor.getSourceEditor();
+  yield checkDiskCacheFor(TEST_HOST);
 
-  await toolbox.destroy();
+  yield toolbox.destroy();
 
   let onUnload = new Promise(done => {
     win.addEventListener("unload", function listener(event) {
@@ -37,7 +37,7 @@ add_task(async function () {
     });
   });
   win.close();
-  await onUnload;
+  yield onUnload;
 });
 
 function checkDiskCacheFor(host) {
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_reload.js b/devtools/client/styleeditor/test/browser_styleeditor_reload.js
index 94e4a63fc28c..a4991fb44f12 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_reload.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_reload.js
@@ -10,20 +10,20 @@ const TESTCASE_URI = TEST_BASE_HTTPS + "simple.html";
 const LINE_NO = 5;
 const COL_NO = 3;
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "Two sheets present after load.");
 
   info("Selecting the second editor");
-  await ui.selectStyleSheet(ui.editors[1].styleSheet, LINE_NO, COL_NO);
+  yield ui.selectStyleSheet(ui.editors[1].styleSheet, LINE_NO, COL_NO);
 
-  await reloadPageAndWaitForStyleSheets(ui);
+  yield reloadPageAndWaitForStyleSheets(ui);
 
   is(ui.editors.length, 2, "Two sheets present after reload.");
 
   info("Waiting for source editor to be ready.");
-  await ui.editors[1].getSourceEditor();
+  yield ui.editors[1].getSourceEditor();
 
   is(ui.selectedEditor, ui.editors[1],
     "second editor is selected after reload");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_scroll.js b/devtools/client/styleeditor/test/browser_styleeditor_scroll.js
index cecea4aeb4ac..b6c3dcfe9598 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_scroll.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_scroll.js
@@ -24,8 +24,8 @@ const DOCUMENT_WITH_LONG_SHEET = "data:text/html;charset=UTF-8," +
           ].join("\n"));
 const LINE_TO_SELECT = 201;
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(DOCUMENT_WITH_LONG_SHEET);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(DOCUMENT_WITH_LONG_SHEET);
 
   is(ui.editors.length, 2, "Two editors present.");
 
@@ -38,8 +38,8 @@ add_task(async function () {
   // position as scrolling occurs after selectStyleSheet resolves but before the
   // event is emitted.
   let selectEventPromise = waitForEditorToBeSelected(longEditor, ui);
-  await ui.selectStyleSheet(longEditor.styleSheet, LINE_TO_SELECT);
-  await selectEventPromise;
+  yield ui.selectStyleSheet(longEditor.styleSheet, LINE_TO_SELECT);
+  yield selectEventPromise;
 
   info("Checking that the correct line is visible after initial load");
 
@@ -53,18 +53,18 @@ add_task(async function () {
   info(`Storing scrollTop = ${initialScrollTop} for later comparison.`);
 
   info("Selecting the first editor (simple.css)");
-  await ui.selectStyleSheet(simpleEditor.styleSheet);
+  yield ui.selectStyleSheet(simpleEditor.styleSheet);
 
   info("Selecting doc_long.css again.");
   selectEventPromise = waitForEditorToBeSelected(longEditor, ui);
 
   // Can't use ui.selectStyleSheet here as it will scroll the editor back to top
   // and we want to check that the previous scroll position is restored.
-  let summary = await ui.getEditorSummary(longEditor);
+  let summary = yield ui.getEditorSummary(longEditor);
   ui._view.activeSummary = summary;
 
   info("Waiting for doc_long.css to be selected.");
-  await selectEventPromise;
+  yield selectEventPromise;
 
   let scrollTop = longEditor.sourceEditor.getScrollInfo().top;
   is(scrollTop, initialScrollTop,
@@ -79,13 +79,13 @@ add_task(async function () {
  * @param {StyleEditorUI} ui
  *        The StyleEditorUI the editor belongs to.
  */
-var waitForEditorToBeSelected = async function (editor, ui) {
+var waitForEditorToBeSelected = Task.async(function* (editor, ui) {
   info(`Waiting for ${editor.friendlyName} to be selected.`);
-  let selected = await ui.once("editor-selected");
+  let selected = yield ui.once("editor-selected");
   while (selected != editor) {
     info(`Ignored editor-selected for editor ${editor.friendlyName}.`);
-    selected = await ui.once("editor-selected");
+    selected = yield ui.once("editor-selected");
   }
 
   info(`Got editor-selected for ${editor.friendlyName}.`);
-};
+});
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_selectstylesheet.js b/devtools/client/styleeditor/test/browser_styleeditor_selectstylesheet.js
index 4ced99e3fbf2..4d9692f9f52d 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_selectstylesheet.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_selectstylesheet.js
@@ -11,12 +11,12 @@ const TESTCASE_URI = TEST_BASE_HTTPS + "simple.html";
 const LINE_NO = 5;
 const COL_NO = 0;
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
   let editor = ui.editors[1];
 
   info("Selecting style sheet #1.");
-  await ui.selectStyleSheet(editor.styleSheet.href, LINE_NO);
+  yield ui.selectStyleSheet(editor.styleSheet.href, LINE_NO);
 
   is(ui.selectedEditor, ui.editors[1], "Second editor is selected.");
   let {line, ch} = ui.selectedEditor.sourceEditor.getCursor();
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_large.js b/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_large.js
index 5d468bf6b6f6..cddba68777d8 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_large.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_large.js
@@ -11,10 +11,10 @@
 
 const TESTCASE_URI = TEST_BASE_HTTPS + "sourcemaps-large.html";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
-  await openEditor(ui.editors[0]);
+  yield openEditor(ui.editors[0]);
   let iframes = ui.selectedEditor.details.querySelectorAll("iframe");
 
   is(iframes.length, 1, "There is only one editor iframe");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_watching.js b/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_watching.js
index 47e883fbf493..7d508a1aa5ca 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_watching.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sourcemap_watching.js
@@ -19,25 +19,25 @@ const CSS_TEXT = "* { color: blue }";
 const {FileUtils} = ChromeUtils.import("resource://gre/modules/FileUtils.jsm", {});
 const {NetUtil} = ChromeUtils.import("resource://gre/modules/NetUtil.jsm", {});
 
-add_task(async function () {
-  await new Promise(resolve => {
+add_task(function* () {
+  yield new Promise(resolve => {
     SpecialPowers.pushPrefEnv({"set": [
       [TRANSITIONS_PREF, false]
     ]}, resolve);
   });
 
   // copy all our files over so we don't screw them up for other tests
-  let HTMLFile = await copy(TESTCASE_URI_HTML, ["sourcemaps.html"]);
-  let CSSFile = await copy(TESTCASE_URI_CSS,
+  let HTMLFile = yield copy(TESTCASE_URI_HTML, ["sourcemaps.html"]);
+  let CSSFile = yield copy(TESTCASE_URI_CSS,
     ["sourcemap-css", "sourcemaps.css"]);
-  await copy(TESTCASE_URI_SCSS, ["sourcemap-sass", "sourcemaps.scss"]);
-  await copy(TESTCASE_URI_MAP, ["sourcemap-css", "sourcemaps.css.map"]);
-  await copy(TESTCASE_URI_REG_CSS, ["simple.css"]);
+  yield copy(TESTCASE_URI_SCSS, ["sourcemap-sass", "sourcemaps.scss"]);
+  yield copy(TESTCASE_URI_MAP, ["sourcemap-css", "sourcemaps.css.map"]);
+  yield copy(TESTCASE_URI_REG_CSS, ["simple.css"]);
 
   let uri = Services.io.newFileURI(HTMLFile);
   let testcaseURI = uri.resolve("");
 
-  let { ui } = await openStyleEditorForURL(testcaseURI);
+  let { ui } = yield openStyleEditorForURL(testcaseURI);
 
   let editor = ui.editors[1];
   if (getStylesheetNameFor(editor) != TESTCASE_SCSS_NAME) {
@@ -49,29 +49,29 @@ add_task(async function () {
   let link = getLinkFor(editor);
   link.click();
 
-  await editor.getSourceEditor();
+  yield editor.getSourceEditor();
 
-  let color = await getComputedStyleProperty({selector: "div", name: "color"});
+  let color = yield getComputedStyleProperty({selector: "div", name: "color"});
   is(color, "rgb(255, 0, 102)", "div is red before saving file");
 
   // let styleApplied = defer();
   let styleApplied = editor.once("style-applied");
 
-  await pauseForTimeChange();
+  yield pauseForTimeChange();
 
   // Edit and save Sass in the editor. This will start off a file-watching
   // process waiting for the CSS file to change.
-  await editSCSS(editor);
+  yield editSCSS(editor);
 
   // We can't run Sass or another compiler, so we fake it by just
   // directly changing the CSS file.
-  await editCSSFile(CSSFile);
+  yield editCSSFile(CSSFile);
 
   info("wrote to CSS file, waiting for style-applied event");
 
-  await styleApplied;
+  yield styleApplied;
 
-  color = await getComputedStyleProperty({selector: "div", name: "color"});
+  color = yield getComputedStyleProperty({selector: "div", name: "color"});
   is(color, "rgb(0, 0, 255)", "div is blue after saving file");
 
   // Ensure that the editor didn't revert.  Bug 1346662.
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps.js b/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps.js
index f41c77e6ec58..dd3da57eb240 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps.js
@@ -77,8 +77,8 @@ const origNames = ["sourcemaps.scss", "contained.scss", "test-stylus.styl"];
 
 waitForExplicitFinish();
 
-add_task(async function () {
-  let {ui} = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let {ui} = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 4,
     "correct number of editors with source maps enabled");
@@ -87,19 +87,19 @@ add_task(async function () {
   testFirstEditor(ui.editors[0]);
 
   // Test Scss editors
-  await testEditor(ui.editors[1], origNames);
-  await testEditor(ui.editors[2], origNames);
-  await testEditor(ui.editors[3], origNames);
+  yield testEditor(ui.editors[1], origNames);
+  yield testEditor(ui.editors[2], origNames);
+  yield testEditor(ui.editors[3], origNames);
 
   // Test disabling original sources
-  await togglePref(ui);
+  yield togglePref(ui);
 
   is(ui.editors.length, 4, "correct number of editors after pref toggled");
 
   // Test CSS editors
-  await testEditor(ui.editors[1], cssNames);
-  await testEditor(ui.editors[2], cssNames);
-  await testEditor(ui.editors[3], cssNames);
+  yield testEditor(ui.editors[1], cssNames);
+  yield testEditor(ui.editors[2], cssNames);
+  yield testEditor(ui.editors[3], cssNames);
 
   Services.prefs.clearUserPref(PREF);
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps_inline.js b/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps_inline.js
index 6dc2cd915a55..ca84e0074b18 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps_inline.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sourcemaps_inline.js
@@ -30,30 +30,30 @@ body > h1 {
 "4gICAgY29sb3I6IHdoaXRlO1xuICB9XG59XG4iXSwKIm5hbWVzIjogW10sCiJmaWxlIjogInRlc" +
 "3QuY3NzIgp9Cg== */";
 
-add_task(async function () {
-  let {ui} = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let {ui} = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 1,
     "correct number of editors with source maps enabled");
 
-  await testEditor(ui.editors[0], "test.scss", sassContent);
+  yield testEditor(ui.editors[0], "test.scss", sassContent);
 
   // Test disabling original sources
-  await togglePref(ui);
+  yield togglePref(ui);
 
   is(ui.editors.length, 1, "correct number of editors after pref toggled");
 
   // Test CSS editors
-  await testEditor(ui.editors[0], "<inline style sheet #1>", cssContent);
+  yield testEditor(ui.editors[0], "<inline style sheet #1>", cssContent);
 
   Services.prefs.clearUserPref(PREF);
 });
 
-async function testEditor(editor, expectedName, expectedText) {
+function* testEditor(editor, expectedName, expectedText) {
   let name = getStylesheetNameFor(editor);
   is(expectedName, name, name + " editor name is correct");
 
-  await openEditor(editor);
+  yield openEditor(editor);
   let text = editor.sourceEditor.getText();
   is(text, expectedText, name + " editor contains expected text");
 }
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sv_keynav.js b/devtools/client/styleeditor/test/browser_styleeditor_sv_keynav.js
index 989b6c15f961..a9c0073c3c96 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sv_keynav.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sv_keynav.js
@@ -7,11 +7,11 @@
 
 const TESTCASE_URI = TEST_BASE_HTTP + "four.html";
 
-add_task(async function () {
-  let { panel, ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { panel, ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   info("Waiting for source editor to load.");
-  await ui.editors[0].getSourceEditor();
+  yield ui.editors[0].getSourceEditor();
 
   let selected = ui.once("editor-selected");
 
@@ -19,7 +19,7 @@ add_task(async function () {
   testKeyboardNavigation(ui.editors[0], panel);
 
   info("Waiting for editor #2 to be selected due to keyboard navigation.");
-  await selected;
+  yield selected;
 
   ok(ui.editors[2].sourceEditor.hasFocus(), "Editor #2 has focus.");
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sv_resize.js b/devtools/client/styleeditor/test/browser_styleeditor_sv_resize.js
index 84a631327573..d684905fc707 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sv_resize.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sv_resize.js
@@ -10,15 +10,15 @@ const TESTCASE_URI = TEST_BASE_HTTP + "simple.html";
 
 const {Toolbox} = require("devtools/client/framework/toolbox");
 
-add_task(async function () {
-  let { toolbox, ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { toolbox, ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "There are 2 style sheets initially");
 
   info("Changing toolbox host to a window.");
-  await toolbox.switchHost(Toolbox.HostType.WINDOW);
+  yield toolbox.switchHost(Toolbox.HostType.WINDOW);
 
-  let editor = await ui.editors[0].getSourceEditor();
+  let editor = yield ui.editors[0].getSourceEditor();
   let originalSourceEditor = editor.sourceEditor;
 
   let hostWindow = toolbox.win.parent;
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_sync.js b/devtools/client/styleeditor/test/browser_styleeditor_sync.js
index b640c12dbc33..4bff841019a5 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_sync.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_sync.js
@@ -19,24 +19,24 @@ const expectedText = `
   }
   `;
 
-async function closeAndReopenToolbox() {
+function* closeAndReopenToolbox() {
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  await gDevTools.closeToolbox(target);
-  let { ui: newui } = await openStyleEditor();
+  yield gDevTools.closeToolbox(target);
+  let { ui: newui } = yield openStyleEditor();
   return newui;
 }
 
-add_task(async function () {
-  await addTab(TESTCASE_URI);
-  let { inspector, view } = await openRuleView();
-  await selectNode("#testid", inspector);
+add_task(function* () {
+  yield addTab(TESTCASE_URI);
+  let { inspector, view } = yield openRuleView();
+  yield selectNode("#testid", inspector);
   let ruleEditor = getRuleViewRuleEditor(view, 1);
 
   // Disable the "font-size" property.
   let propEditor = ruleEditor.rule.textProps[0].editor;
   let onModification = view.once("ruleview-changed");
   propEditor.enable.click();
-  await onModification;
+  yield onModification;
 
   // Disable the "color" property.  Note that this property is in a
   // rule that also contains a non-inherited property -- so this test
@@ -46,25 +46,25 @@ add_task(async function () {
   propEditor = ruleEditor.rule.textProps[1].editor;
   onModification = view.once("ruleview-changed");
   propEditor.enable.click();
-  await onModification;
+  yield onModification;
 
-  let { ui } = await openStyleEditor();
+  let { ui } = yield openStyleEditor();
 
-  let editor = await ui.editors[0].getSourceEditor();
+  let editor = yield ui.editors[0].getSourceEditor();
   let text = editor.sourceEditor.getText();
   is(text, expectedText, "style inspector changes are synced");
 
   // Close and reopen the toolbox, to see that the edited text remains
   // available.
-  ui = await closeAndReopenToolbox();
-  editor = await ui.editors[0].getSourceEditor();
+  ui = yield closeAndReopenToolbox();
+  editor = yield ui.editors[0].getSourceEditor();
   text = editor.sourceEditor.getText();
   is(text, expectedText, "changes remain after close and reopen");
 
   // For the time being, the actor does not update the style's owning
   // node's textContent.  See bug 1205380.
-  let textContent = await ContentTask.spawn(gBrowser.selectedBrowser, null,
-    async function () {
+  let textContent = yield ContentTask.spawn(gBrowser.selectedBrowser, null,
+    function* () {
       return content.document.querySelector("style").textContent;
     });
 
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_syncAddProperty.js b/devtools/client/styleeditor/test/browser_styleeditor_syncAddProperty.js
index 92fa8e69e649..e197157adce3 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_syncAddProperty.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_syncAddProperty.js
@@ -19,14 +19,14 @@ const expectedText = `
   }
   `;
 
-add_task(async function () {
-  await addTab(TESTCASE_URI);
-  let { inspector, view } = await openRuleView();
-  await selectNode("#testid", inspector);
+add_task(function* () {
+  yield addTab(TESTCASE_URI);
+  let { inspector, view } = yield openRuleView();
+  yield selectNode("#testid", inspector);
 
   info("Focusing a new property name in the rule-view");
   let ruleEditor = getRuleViewRuleEditor(view, 1);
-  let editor = await focusEditableField(view, ruleEditor.closeBrace);
+  let editor = yield focusEditableField(view, ruleEditor.closeBrace);
   is(inplaceEditor(ruleEditor.newPropSpan), editor,
     "The new property editor has focus");
 
@@ -36,10 +36,10 @@ add_task(async function () {
   info("Pressing return to commit and focus the new value field");
   let onModifications = view.once("ruleview-changed");
   EventUtils.synthesizeKey("VK_RETURN", {}, view.styleWindow);
-  await onModifications;
+  yield onModifications;
 
-  let { ui } = await openStyleEditor();
-  let sourceEditor = await ui.editors[0].getSourceEditor();
+  let { ui } = yield openStyleEditor();
+  let sourceEditor = yield ui.editors[0].getSourceEditor();
   let text = sourceEditor.sourceEditor.getText();
   is(text, expectedText, "selector edits are synced");
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_syncAddRule.js b/devtools/client/styleeditor/test/browser_styleeditor_syncAddRule.js
index ef3b2dcfceee..348b9c630aa7 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_syncAddRule.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_syncAddRule.js
@@ -11,19 +11,19 @@ const expectedText = `
 #testid {
 }`;
 
-add_task(async function () {
-  await addTab(TESTCASE_URI);
-  let { inspector, view } = await openRuleView();
-  await selectNode("#testid", inspector);
+add_task(function* () {
+  yield addTab(TESTCASE_URI);
+  let { inspector, view } = yield openRuleView();
+  yield selectNode("#testid", inspector);
 
   let onRuleViewChanged = once(view, "ruleview-changed");
   view.addRuleButton.click();
-  await onRuleViewChanged;
+  yield onRuleViewChanged;
 
-  let { ui } = await openStyleEditor();
+  let { ui } = yield openStyleEditor();
 
   info("Selecting the second editor");
-  await ui.selectStyleSheet(ui.editors[1].styleSheet);
+  yield ui.selectStyleSheet(ui.editors[1].styleSheet);
 
   let editor = ui.editors[1];
   let text = editor.sourceEditor.getText();
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_syncAlreadyOpen.js b/devtools/client/styleeditor/test/browser_styleeditor_syncAlreadyOpen.js
index a1a811b1c547..c781add4555a 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_syncAlreadyOpen.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_syncAlreadyOpen.js
@@ -19,32 +19,32 @@ const expectedText = `
   }
   `;
 
-add_task(async function () {
-  await addTab(TESTCASE_URI);
+add_task(function* () {
+  yield addTab(TESTCASE_URI);
 
-  let { inspector, view, toolbox } = await openRuleView();
+  let { inspector, view, toolbox } = yield openRuleView();
 
   // In this test, make sure the style editor is open before making
   // changes in the inspector.
-  let { ui } = await openStyleEditor();
-  let editor = await ui.editors[0].getSourceEditor();
+  let { ui } = yield openStyleEditor();
+  let editor = yield ui.editors[0].getSourceEditor();
 
   let onEditorChange = new Promise(resolve => {
     editor.sourceEditor.on("change", resolve);
   });
 
-  await toolbox.getPanel("inspector");
-  await selectNode("#testid", inspector);
+  yield toolbox.getPanel("inspector");
+  yield selectNode("#testid", inspector);
   let ruleEditor = getRuleViewRuleEditor(view, 1);
 
   // Disable the "font-size" property.
   let propEditor = ruleEditor.rule.textProps[0].editor;
   let onModification = view.once("ruleview-changed");
   propEditor.enable.click();
-  await onModification;
+  yield onModification;
 
-  await openStyleEditor();
-  await onEditorChange;
+  yield openStyleEditor();
+  yield onEditorChange;
 
   let text = editor.sourceEditor.getText();
   is(text, expectedText, "style inspector changes are synced");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_syncEditSelector.js b/devtools/client/styleeditor/test/browser_styleeditor_syncEditSelector.js
index 97d9b1fd2cd9..0725d574039e 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_syncEditSelector.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_syncEditSelector.js
@@ -19,21 +19,21 @@ const expectedText = `
   }
   `;
 
-add_task(async function () {
-  await addTab(TESTCASE_URI);
-  let { inspector, view } = await openRuleView();
-  await selectNode("#testid", inspector);
+add_task(function* () {
+  yield addTab(TESTCASE_URI);
+  let { inspector, view } = yield openRuleView();
+  yield selectNode("#testid", inspector);
   let ruleEditor = getRuleViewRuleEditor(view, 1);
 
-  let editor = await focusEditableField(view, ruleEditor.selectorText);
+  let editor = yield focusEditableField(view, ruleEditor.selectorText);
   editor.input.value = "#testid, span";
   let onRuleViewChanged = once(view, "ruleview-changed");
   EventUtils.synthesizeKey("KEY_Enter");
-  await onRuleViewChanged;
+  yield onRuleViewChanged;
 
-  let { ui } = await openStyleEditor();
+  let { ui } = yield openStyleEditor();
 
-  editor = await ui.editors[0].getSourceEditor();
+  editor = yield ui.editors[0].getSourceEditor();
   let text = editor.sourceEditor.getText();
   is(text, expectedText, "selector edits are synced");
 });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_syncIntoRuleView.js b/devtools/client/styleeditor/test/browser_styleeditor_syncIntoRuleView.js
index 8ed00eec5d24..14d548f2b4de 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_syncIntoRuleView.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_syncIntoRuleView.js
@@ -14,19 +14,19 @@ const TEST_URI = `
 
 const TESTCASE_CSS_SOURCE = "#testid { color: chartreuse; }";
 
-add_task(async function () {
-  await addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
+add_task(function* () {
+  yield addTab("data:text/html;charset=utf-8," + encodeURIComponent(TEST_URI));
 
-  let {inspector, view} = await openRuleView();
-  await selectNode("#testid", inspector);
+  let {inspector, view} = yield openRuleView();
+  yield selectNode("#testid", inspector);
 
-  let { panel, ui } = await openStyleEditor();
+  let { panel, ui } = yield openStyleEditor();
 
-  let editor = await ui.editors[0].getSourceEditor();
+  let editor = yield ui.editors[0].getSourceEditor();
 
   let waitForRuleView = view.once("ruleview-refreshed");
-  await typeInEditor(editor, panel.panelWindow);
-  await waitForRuleView;
+  yield typeInEditor(editor, panel.panelWindow);
+  yield waitForRuleView;
 
   let value = getRuleViewPropertyValue(view, "#testid", "color");
   is(value, "chartreuse", "check that edits were synced to rule view");
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_transition_rule.js b/devtools/client/styleeditor/test/browser_styleeditor_transition_rule.js
index 120c88f863e9..f0e44a931d64 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_transition_rule.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_transition_rule.js
@@ -8,13 +8,13 @@ const TESTCASE_URI = TEST_BASE_HTTPS + "simple.html";
 
 const NEW_RULE = "body { background-color: purple; }";
 
-add_task(async function () {
-  let { ui } = await openStyleEditorForURL(TESTCASE_URI);
+add_task(function* () {
+  let { ui } = yield openStyleEditorForURL(TESTCASE_URI);
 
   is(ui.editors.length, 2, "correct number of editors");
 
   let editor = ui.editors[0];
-  await openEditor(editor);
+  yield openEditor(editor);
 
   // Set text twice in a row
   let styleChanges = listenForStyleChange(editor.styleSheet);
@@ -22,10 +22,10 @@ add_task(async function () {
   editor.sourceEditor.setText(NEW_RULE);
   editor.sourceEditor.setText(NEW_RULE + " ");
 
-  await styleChanges;
+  yield styleChanges;
 
-  let rules = await ContentTask.spawn(gBrowser.selectedBrowser, 0,
-  async function (index) {
+  let rules = yield ContentTask.spawn(gBrowser.selectedBrowser, 0,
+  function* (index) {
     let sheet = content.document.styleSheets[index];
     return [...sheet.cssRules].map(rule => rule.cssText);
   });
diff --git a/devtools/client/styleeditor/test/browser_styleeditor_xul.js b/devtools/client/styleeditor/test/browser_styleeditor_xul.js
index 8bd1ea5adc52..931ad92e7422 100644
--- a/devtools/client/styleeditor/test/browser_styleeditor_xul.js
+++ b/devtools/client/styleeditor/test/browser_styleeditor_xul.js
@@ -10,11 +10,11 @@ waitForExplicitFinish();
 
 const TEST_URL = TEST_BASE + "doc_xulpage.xul";
 
-add_task(async function () {
-  let tab = await addTab(TEST_URL);
+add_task(function* () {
+  let tab = yield addTab(TEST_URL);
   let target = TargetFactory.forTab(tab);
 
-  let toolbox = await gDevTools.showToolbox(target, "styleeditor");
+  let toolbox = yield gDevTools.showToolbox(target, "styleeditor");
   let panel = toolbox.getCurrentPanel();
 
   ok(panel,
diff --git a/devtools/client/styleeditor/test/head.js b/devtools/client/styleeditor/test/head.js
index d9ceed7452b0..ca5eafee4f33 100644
--- a/devtools/client/styleeditor/test/head.js
+++ b/devtools/client/styleeditor/test/head.js
@@ -50,50 +50,50 @@ var navigateTo = function (url) {
   return BrowserTestUtils.browserLoaded(browser);
 };
 
-var navigateToAndWaitForStyleSheets = async function (url, ui) {
+var navigateToAndWaitForStyleSheets = Task.async(function* (url, ui) {
   let onReset = ui.once("stylesheets-reset");
-  await navigateTo(url);
-  await onReset;
-};
+  yield navigateTo(url);
+  yield onReset;
+});
 
-var reloadPageAndWaitForStyleSheets = async function (ui) {
+var reloadPageAndWaitForStyleSheets = Task.async(function* (ui) {
   info("Reloading the page.");
 
   let onReset = ui.once("stylesheets-reset");
   let browser = gBrowser.selectedBrowser;
-  await ContentTask.spawn(browser, null, "() => content.location.reload()");
-  await onReset;
-};
+  yield ContentTask.spawn(browser, null, "() => content.location.reload()");
+  yield onReset;
+});
 
 /**
  * Open the style editor for the current tab.
  */
-var openStyleEditor = async function (tab) {
+var openStyleEditor = Task.async(function* (tab) {
   if (!tab) {
     tab = gBrowser.selectedTab;
   }
   let target = TargetFactory.forTab(tab);
-  let toolbox = await gDevTools.showToolbox(target, "styleeditor");
+  let toolbox = yield gDevTools.showToolbox(target, "styleeditor");
   let panel = toolbox.getPanel("styleeditor");
   let ui = panel.UI;
 
   // The stylesheet list appears with an animation. Let this animation finish.
   let animations = ui._root.getAnimations({subtree: true});
-  await Promise.all(animations.map(a => a.finished));
+  yield Promise.all(animations.map(a => a.finished));
 
   return { toolbox, panel, ui };
-};
+});
 
 /**
  * Creates a new tab in specified window navigates it to the given URL and
  * opens style editor in it.
  */
-var openStyleEditorForURL = async function (url, win) {
-  let tab = await addTab(url, win);
-  let result = await openStyleEditor(tab);
+var openStyleEditorForURL = Task.async(function* (url, win) {
+  let tab = yield addTab(url, win);
+  let result = yield openStyleEditor(tab);
   result.tab = tab;
   return result;
-};
+});
 
 /**
  * Send an async message to the frame script and get back the requested
@@ -106,8 +106,8 @@ var openStyleEditorForURL = async function (url, win) {
  * @param {String} name
  *        name of the property.
  */
-var getComputedStyleProperty = async function (args) {
-  return ContentTask.spawn(gBrowser.selectedBrowser, args,
+var getComputedStyleProperty = function* (args) {
+  return yield ContentTask.spawn(gBrowser.selectedBrowser, args,
     function ({selector, pseudo, name}) {
       let element = content.document.querySelector(selector);
       let style = content.getComputedStyle(element, pseudo);
diff --git a/devtools/client/webaudioeditor/controller.js b/devtools/client/webaudioeditor/controller.js
index 4be926a3c630..efefc9c1598f 100644
--- a/devtools/client/webaudioeditor/controller.js
+++ b/devtools/client/webaudioeditor/controller.js
@@ -43,7 +43,7 @@ var WebAudioEditorController = {
   /**
    * Listen for events emitted by the current tab target.
    */
-  async initialize() {
+  initialize: Task.async(function* () {
     this._onTabNavigated = this._onTabNavigated.bind(this);
     this._onThemeChange = this._onThemeChange.bind(this);
 
@@ -67,9 +67,9 @@ var WebAudioEditorController = {
     // Store the AudioNode definitions from the WebAudioFront, if the method exists.
     // If not, get the JSON directly. Using the actor method is preferable so the client
     // knows exactly what methods are supported on the server.
-    let actorHasDefinition = await gTarget.actorHasMethod("webaudio", "getDefinition");
+    let actorHasDefinition = yield gTarget.actorHasMethod("webaudio", "getDefinition");
     if (actorHasDefinition) {
-      AUDIO_NODE_DEFINITION = await gFront.getDefinition();
+      AUDIO_NODE_DEFINITION = yield gFront.getDefinition();
     } else {
       AUDIO_NODE_DEFINITION = require("devtools/server/actors/utils/audionodes.json");
     }
@@ -79,7 +79,7 @@ var WebAudioEditorController = {
     // early request to ensure the CallWatcherActor is running and watching for new window
     // globals.
     gFront.setup({ reload: false });
-  },
+  }),
 
   /**
    * Remove events emitted by the current tab target.
@@ -112,7 +112,7 @@ var WebAudioEditorController = {
   // Since node events (create, disconnect, connect) are all async,
   // we have to make sure to wait that the node has finished creating
   // before performing an operation on it.
-  getNode: async function (nodeActor) {
+  getNode: function* (nodeActor) {
     let id = nodeActor.actorID;
     let node = gAudioNodes.get(id);
 
@@ -124,7 +124,7 @@ var WebAudioEditorController = {
           resolve(createdNode);
         }
       });
-      node = await promise;
+      node = yield promise;
     }
     return node;
   },
@@ -142,7 +142,7 @@ var WebAudioEditorController = {
   /**
    * Called for each location change in the debugged tab.
    */
-  async _onTabNavigated(event, {isFrameSwitching}) {
+  _onTabNavigated: Task.async(function* (event, {isFrameSwitching}) {
     switch (event) {
       case "will-navigate": {
         // Clear out current UI.
@@ -173,7 +173,7 @@ var WebAudioEditorController = {
         break;
       }
     }
-  },
+  }),
 
   /**
    * Called after the first audio node is created in an audio context,
@@ -205,34 +205,34 @@ var WebAudioEditorController = {
   /**
    * Called when a node is connected to another node.
    */
-  async _onConnectNode({ source: sourceActor, dest: destActor }) {
-    let source = await WebAudioEditorController.getNode(sourceActor);
-    let dest = await WebAudioEditorController.getNode(destActor);
+  _onConnectNode: Task.async(function* ({ source: sourceActor, dest: destActor }) {
+    let source = yield WebAudioEditorController.getNode(sourceActor);
+    let dest = yield WebAudioEditorController.getNode(destActor);
     source.connect(dest);
-  },
+  }),
 
   /**
    * Called when a node is conneceted to another node's AudioParam.
    */
-  async _onConnectParam({ source: sourceActor, dest: destActor, param }) {
-    let source = await WebAudioEditorController.getNode(sourceActor);
-    let dest = await WebAudioEditorController.getNode(destActor);
+  _onConnectParam: Task.async(function* ({ source: sourceActor, dest: destActor, param }) {
+    let source = yield WebAudioEditorController.getNode(sourceActor);
+    let dest = yield WebAudioEditorController.getNode(destActor);
     source.connect(dest, param);
-  },
+  }),
 
   /**
    * Called when a node is disconnected.
    */
-  async _onDisconnectNode(nodeActor) {
-    let node = await WebAudioEditorController.getNode(nodeActor);
+  _onDisconnectNode: Task.async(function* (nodeActor) {
+    let node = yield WebAudioEditorController.getNode(nodeActor);
     node.disconnect();
-  },
+  }),
 
   /**
    * Called when a node param is changed.
    */
-  async _onChangeParam({ actor, param, value }) {
-    let node = await WebAudioEditorController.getNode(actor);
+  _onChangeParam: Task.async(function* ({ actor, param, value }) {
+    let node = yield WebAudioEditorController.getNode(actor);
     window.emit(EVENTS.CHANGE_PARAM, node, param, value);
-  }
+  })
 };
diff --git a/devtools/client/webaudioeditor/includes.js b/devtools/client/webaudioeditor/includes.js
index bbbbf7e936f5..ec0257619b26 100644
--- a/devtools/client/webaudioeditor/includes.js
+++ b/devtools/client/webaudioeditor/includes.js
@@ -5,6 +5,7 @@
 
 const { loader, require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
 const { XPCOMUtils } = require("resource://gre/modules/XPCOMUtils.jsm");
+const { Task } = require("devtools/shared/task");
 const EventEmitter = require("devtools/shared/event-emitter");
 const DevToolsUtils = require("devtools/shared/DevToolsUtils");
 const Services = require("Services");
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-add-automation-event.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-add-automation-event.js
index f7e2309e8175..4b451c826ddc 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-add-automation-event.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-add-automation-event.js
@@ -5,9 +5,9 @@
  * Test AudioNode#addAutomationEvent();
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, [destNode, oscNode, gainNode]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
     front.setup({ reload: true }),
     get3(front, "create-node")
   ]);
@@ -17,27 +17,27 @@ add_task(async function () {
 
   let t0 = 0, t1 = 0.1, t2 = 0.2, t3 = 0.3, t4 = 0.4, t5 = 0.6, t6 = 0.7, t7 = 1;
   let curve = [-1, 0, 1];
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
-  await oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
-  await oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
-  await oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
-  await oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.5, t6]);
-  await oscNode.addAutomationEvent("frequency", "setValueCurveAtTime", [curve, t7, t7 - t6]);
-  await oscNode.addAutomationEvent("frequency", "setTargetAtTime", [20, 2, 5]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.5, t6]);
+  yield oscNode.addAutomationEvent("frequency", "setValueCurveAtTime", [curve, t7, t7 - t6]);
+  yield oscNode.addAutomationEvent("frequency", "setTargetAtTime", [20, 2, 5]);
 
   ok(true, "successfully set automation events for valid automation events");
 
   try {
-    await oscNode.addAutomationEvent("frequency", "notAMethod", 20, 2, 5);
+    yield oscNode.addAutomationEvent("frequency", "notAMethod", 20, 2, 5);
     ok(false, "non-automation methods should not be successful");
   } catch (e) {
     ok(/invalid/.test(e.message), "AudioNode:addAutomationEvent fails for invalid automation methods");
   }
 
   try {
-    await oscNode.addAutomationEvent("invalidparam", "setValueAtTime", 0.2, t0);
+    yield oscNode.addAutomationEvent("invalidparam", "setValueAtTime", 0.2, t0);
     ok(false, "automating non-AudioParams should not be successful");
   } catch (e) {
     ok(/invalid/.test(e.message), "AudioNode:addAutomationEvent fails for a non AudioParam");
@@ -48,5 +48,5 @@ add_task(async function () {
   is(count, 9,
     "when calling `addAutomationEvent`, the WebAudioActor should still fire `automation-event`.");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-bypass.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-bypass.js
index 008e3bb80e87..e9fc7f321f08 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-bypass.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-bypass.js
@@ -5,32 +5,32 @@
  * Test AudioNode#bypass(), AudioNode#isBypassed()
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, [destNode, oscNode, gainNode]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
     front.setup({ reload: true }),
     get3(front, "create-node")
   ]);
 
-  is((await gainNode.isBypassed()), false, "Nodes start off unbypassed.");
+  is((yield gainNode.isBypassed()), false, "Nodes start off unbypassed.");
 
   info("Calling node#bypass(true)");
-  let isBypassed = await gainNode.bypass(true);
+  let isBypassed = yield gainNode.bypass(true);
 
   is(isBypassed, true, "node.bypass(true) resolves to true");
-  is((await gainNode.isBypassed()), true, "Node is now bypassed.");
+  is((yield gainNode.isBypassed()), true, "Node is now bypassed.");
 
   info("Calling node#bypass(false)");
-  isBypassed = await gainNode.bypass(false);
+  isBypassed = yield gainNode.bypass(false);
 
   is(isBypassed, false, "node.bypass(false) resolves to false");
-  is((await gainNode.isBypassed()), false, "Node back to being unbypassed.");
+  is((yield gainNode.isBypassed()), false, "Node back to being unbypassed.");
 
   info("Calling node#bypass(true) on unbypassable node");
-  isBypassed = await destNode.bypass(true);
+  isBypassed = yield destNode.bypass(true);
 
   is(isBypassed, false, "node.bypass(true) resolves to false for unbypassable node");
-  is((await gainNode.isBypassed()), false, "Unbypassable node is unaffect");
+  is((yield gainNode.isBypassed()), false, "Unbypassable node is unaffect");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-bypassable.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-bypassable.js
index 40ff60e33897..2f093f2e4c1a 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-bypassable.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-bypassable.js
@@ -5,9 +5,9 @@
  * Test AudioNode#bypassable
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_NODES_URL);
-  let [_, nodes] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_NODES_URL);
+  let [_, nodes] = yield Promise.all([
     front.setup({ reload: true }),
     getN(front, "create-node", 14)
   ]);
@@ -34,5 +34,5 @@ add_task(async function () {
     is(actualBypassability[i], bypassable, `${nodes[i].type} has correct ".bypassable" status`);
   });
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-connectnode-disconnect.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-connectnode-disconnect.js
index 94426813a6ba..dcd1689f5e72 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-connectnode-disconnect.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-connectnode-disconnect.js
@@ -6,8 +6,8 @@
  * Uses the editor front as the actors do not retain connect state.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
@@ -16,12 +16,12 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let [dest, osc, gain] = actors;
 
   info("Disconnecting oscillator...");
   osc.disconnect();
-  await Promise.all([
+  yield Promise.all([
     waitForGraphRendered(panelWin, 3, 1),
     once(gAudioNodes, "disconnect")
   ]);
@@ -29,11 +29,11 @@ add_task(async function () {
 
   info("Reconnecting oscillator...");
   osc.connectNode(gain);
-  await Promise.all([
+  yield Promise.all([
     waitForGraphRendered(panelWin, 3, 2),
     once(gAudioNodes, "connect")
   ]);
   ok(true, "Oscillator reconnected.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-connectparam.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-connectparam.js
index 54c9b840e864..454f0d563b77 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-connectparam.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-connectparam.js
@@ -6,8 +6,8 @@
  * Uses the editor front as the actors do not retain connect state.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
@@ -16,17 +16,17 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let [dest, osc, gain] = actors;
 
-  await osc.disconnect();
+  yield osc.disconnect();
 
   osc.connectParam(gain, "gain");
-  await Promise.all([
+  yield Promise.all([
     waitForGraphRendered(panelWin, 3, 1, 1),
     once(gAudioNodes, "connect")
   ]);
   ok(true, "Oscillator connect to Gain's Gain AudioParam, event emitted.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js
index de5526d23efe..640b3e3514df 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-01.js
@@ -6,27 +6,27 @@
  * a curve as the last event to check duration spread.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, [destNode, oscNode, gainNode]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
     front.setup({ reload: true }),
     get3(front, "create-node")
   ]);
 
   let t0 = 0, t1 = 0.1, t2 = 0.2, t3 = 0.3, t4 = 0.4, t5 = 0.6, t6 = 0.7, t7 = 1;
   let curve = [-1, 0, 1];
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
-  await oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
-  await oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
-  await oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
-  await oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.05, t6]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.2, t0]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.3, t1]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [0.4, t2]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [1, t3]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [0.15, t4]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.75, t5]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [0.05, t6]);
   // End with a curve here so we can get proper results on the last event (which takes into account
   // duration)
-  await oscNode.addAutomationEvent("frequency", "setValueCurveAtTime", [curve, t6, t7 - t6]);
+  yield oscNode.addAutomationEvent("frequency", "setValueCurveAtTime", [curve, t6, t7 - t6]);
 
-  let { events, values } = await oscNode.getAutomationData("frequency");
+  let { events, values } = yield oscNode.getAutomationData("frequency");
 
   is(events.length, 8, "8 recorded events returned.");
   is(values.length, 2000, "2000 value points returned.");
@@ -49,5 +49,5 @@ add_task(async function () {
   checkAutomationValue(values, 0.9, 1);
   checkAutomationValue(values, 1, 1);
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js
index 0d35b463f355..f24fb1905327 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-02.js
@@ -6,21 +6,21 @@
  * `setTargetAtTime`, which approaches its target to infinity.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, [destNode, oscNode, gainNode]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
     front.setup({ reload: true }),
     get3(front, "create-node")
   ]);
 
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [300, 0.1]);
-  await oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [500, 0.4]);
-  await oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [200, 0.6]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [300, 0.1]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [500, 0.4]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [200, 0.6]);
   // End with a setTargetAtTime event, as the target approaches infinity, which will
   // give us more points to render than the default 2000
-  await oscNode.addAutomationEvent("frequency", "setTargetAtTime", [1000, 2, 0.5]);
+  yield oscNode.addAutomationEvent("frequency", "setTargetAtTime", [1000, 2, 0.5]);
 
-  var { events, values } = await oscNode.getAutomationData("frequency");
+  var { events, values } = yield oscNode.getAutomationData("frequency");
 
   is(events.length, 4, "4 recorded events returned.");
   is(values.length, 4000, "4000 value points returned when ending with exponentiall approaching automator.");
@@ -31,12 +31,12 @@ add_task(async function () {
   checkAutomationValue(values, 5, 998.01);
 
   // Refetch the automation data to ensure it recalculates correctly (bug 1118071)
-  var { events, values } = await oscNode.getAutomationData("frequency");
+  var { events, values } = yield oscNode.getAutomationData("frequency");
 
   checkAutomationValue(values, 2.01, 215.055);
   checkAutomationValue(values, 2.1, 345.930);
   checkAutomationValue(values, 3, 891.601);
   checkAutomationValue(values, 5, 998.01);
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-03.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-03.js
index c7505385b988..7de509ccd1e4 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-03.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-automation-data-03.js
@@ -6,20 +6,20 @@
  * its argument.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, [destNode, oscNode, gainNode]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
     front.setup({ reload: true }),
     get3(front, "create-node")
   ]);
 
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [300, 0]);
-  await oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [500, 0.9]);
-  await oscNode.addAutomationEvent("frequency", "setValueAtTime", [700, 1]);
-  await oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [1000, 2]);
-  await oscNode.addAutomationEvent("frequency", "cancelScheduledValues", [1]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [300, 0]);
+  yield oscNode.addAutomationEvent("frequency", "linearRampToValueAtTime", [500, 0.9]);
+  yield oscNode.addAutomationEvent("frequency", "setValueAtTime", [700, 1]);
+  yield oscNode.addAutomationEvent("frequency", "exponentialRampToValueAtTime", [1000, 2]);
+  yield oscNode.addAutomationEvent("frequency", "cancelScheduledValues", [1]);
 
-  var { events, values } = await oscNode.getAutomationData("frequency");
+  var { events, values } = yield oscNode.getAutomationData("frequency");
 
   is(events.length, 2, "2 recorded events returned.");
   is(values.length, 2000, "2000 value points returned");
@@ -30,5 +30,5 @@ add_task(async function () {
   checkAutomationValue(values, 1, 499.9);
   checkAutomationValue(values, 2, 499.9);
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-param-flags.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-param-flags.js
index fba642de0793..17f7bf846547 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-param-flags.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-param-flags.js
@@ -5,14 +5,14 @@
  * Test AudioNode#getParamFlags()
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_NODES_URL);
-  let [_, nodes] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_NODES_URL);
+  let [_, nodes] = yield Promise.all([
     front.setup({ reload: true }),
     getN(front, "create-node", 15)
   ]);
 
-  let allNodeParams = await Promise.all(nodes.map(node => node.getParams()));
+  let allNodeParams = yield Promise.all(nodes.map(node => node.getParams()));
   let nodeTypes = [
     "AudioDestinationNode",
     "AudioBufferSourceNode", "ScriptProcessorNode", "AnalyserNode", "GainNode",
@@ -28,7 +28,7 @@ add_task(async function () {
     let params = allNodeParams[i];
 
     for (let {param, value, flags} of params) {
-      let testFlags = await nodes[i].getParamFlags(param);
+      let testFlags = yield nodes[i].getParamFlags(param);
       ok(typeof testFlags === "object", type + " has flags from #getParamFlags(" + param + ")");
 
       if (param === "buffer") {
@@ -43,5 +43,5 @@ add_task(async function () {
     }
   }
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-01.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-01.js
index f0586a4d970b..e0d26dd9dbe0 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-01.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-01.js
@@ -5,16 +5,16 @@
  * Test AudioNode#getParams()
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_NODES_URL);
-  let [_, nodes] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_NODES_URL);
+  let [_, nodes] = yield Promise.all([
     front.setup({ reload: true }),
     getN(front, "create-node", 15)
   ]);
 
-  await loadFrameScriptUtils();
+  yield loadFrameScriptUtils();
 
-  let allNodeParams = await Promise.all(nodes.map(node => node.getParams()));
+  let allNodeParams = yield Promise.all(nodes.map(node => node.getParams()));
   let nodeTypes = [
     "AudioDestinationNode",
     "AudioBufferSourceNode", "ScriptProcessorNode", "AnalyserNode", "GainNode",
@@ -23,7 +23,7 @@ add_task(async function () {
     "StereoPannerNode"
   ];
 
-  let defaults = await Promise.all(nodeTypes.map(type => nodeDefaultValues(type)));
+  let defaults = yield Promise.all(nodeTypes.map(type => nodeDefaultValues(type)));
 
   nodeTypes.map((type, i) => {
     let params = allNodeParams[i];
@@ -45,5 +45,5 @@ add_task(async function () {
     });
   });
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-02.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-02.js
index 4ee7c11087f8..ac9c95dc02ae 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-02.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-params-02.js
@@ -6,16 +6,16 @@
  * from the AudioNode actors.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_NODES_URL);
-  let [_, nodes] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_NODES_URL);
+  let [_, nodes] = yield Promise.all([
     front.setup({ reload: true }),
     getN(front, "create-node", 15)
   ]);
 
-  await loadFrameScriptUtils();
+  yield loadFrameScriptUtils();
 
-  let allParams = await Promise.all(nodes.map(node => node.getParams()));
+  let allParams = yield Promise.all(nodes.map(node => node.getParams()));
   let types = [
     "AudioDestinationNode", "AudioBufferSourceNode", "ScriptProcessorNode",
     "AnalyserNode", "GainNode", "DelayNode", "BiquadFilterNode", "WaveShaperNode",
@@ -23,7 +23,7 @@ add_task(async function () {
     "DynamicsCompressorNode", "OscillatorNode", "StereoPannerNode"
   ];
 
-  let defaults = await Promise.all(types.map(type => nodeDefaultValues(type)));
+  let defaults = yield Promise.all(types.map(type => nodeDefaultValues(type)));
 
   info(JSON.stringify(defaults));
 
@@ -31,7 +31,7 @@ add_task(async function () {
     compare(params, defaults[i], types[i]);
   });
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
 
 function compare(actual, expected, type) {
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-set-param.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-set-param.js
index 4702a92c7bb7..0d4c7c5c7538 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-get-set-param.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-get-set-param.js
@@ -5,43 +5,43 @@
  * Test AudioNode#getParam() / AudioNode#setParam()
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, [destNode, oscNode, gainNode]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, [destNode, oscNode, gainNode]] = yield Promise.all([
     front.setup({ reload: true }),
     get3(front, "create-node")
   ]);
 
-  let freq = await oscNode.getParam("frequency");
+  let freq = yield oscNode.getParam("frequency");
   info(typeof freq);
   is(freq, 440, "AudioNode:getParam correctly fetches AudioParam");
 
-  let type = await oscNode.getParam("type");
+  let type = yield oscNode.getParam("type");
   is(type, "sine", "AudioNode:getParam correctly fetches non-AudioParam");
 
-  type = await oscNode.getParam("not-a-valid-param");
+  type = yield oscNode.getParam("not-a-valid-param");
   ok(type.type === "undefined",
     "AudioNode:getParam correctly returns a grip value for `undefined` for an invalid param.");
 
-  let resSuccess = await oscNode.setParam("frequency", 220);
-  freq = await oscNode.getParam("frequency");
+  let resSuccess = yield oscNode.setParam("frequency", 220);
+  freq = yield oscNode.getParam("frequency");
   is(freq, 220, "AudioNode:setParam correctly sets a `number` AudioParam");
   is(resSuccess, undefined, "AudioNode:setParam returns undefined for correctly set AudioParam");
 
-  resSuccess = await oscNode.setParam("type", "square");
-  type = await oscNode.getParam("type");
+  resSuccess = yield oscNode.setParam("type", "square");
+  type = yield oscNode.getParam("type");
   is(type, "square", "AudioNode:setParam correctly sets a `string` non-AudioParam");
   is(resSuccess, undefined, "AudioNode:setParam returns undefined for correctly set AudioParam");
 
   try {
-    await oscNode.setParam("frequency", "hello");
+    yield oscNode.setParam("frequency", "hello");
     ok(false, "setParam with invalid types should throw");
   } catch (e) {
     ok(/is not a finite floating-point/.test(e.message), "AudioNode:setParam returns error with correct message when attempting an invalid assignment");
     is(e.type, "TypeError", "AudioNode:setParam returns error with correct type when attempting an invalid assignment");
-    freq = await oscNode.getParam("frequency");
+    freq = yield oscNode.getParam("frequency");
     is(freq, 220, "AudioNode:setParam does not modify value when an error occurs");
   }
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-source.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-source.js
index 6845f197fbbd..203e88012239 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-source.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-source.js
@@ -5,9 +5,9 @@
  * Test AudioNode#source
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_NODES_URL);
-  let [_, nodes] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_NODES_URL);
+  let [_, nodes] = yield Promise.all([
     front.setup({ reload: true }),
     getN(front, "create-node", 14)
   ]);
@@ -23,5 +23,5 @@ add_task(async function () {
       is(isSourceResult[i], false, type + "'s `source` is `false`");
   });
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_audionode-actor-type.js b/devtools/client/webaudioeditor/test/browser_audionode-actor-type.js
index 3f57a3ceff59..58712067e60d 100644
--- a/devtools/client/webaudioeditor/test/browser_audionode-actor-type.js
+++ b/devtools/client/webaudioeditor/test/browser_audionode-actor-type.js
@@ -5,9 +5,9 @@
  * Test AudioNode#type
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_NODES_URL);
-  let [_, nodes] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_NODES_URL);
+  let [_, nodes] = yield Promise.all([
     front.setup({ reload: true }),
     getN(front, "create-node", 14)
   ]);
@@ -24,5 +24,5 @@ add_task(async function () {
     is(actualTypes[i], type, type + " successfully created with correct type");
   });
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_callwatcher-01.js b/devtools/client/webaudioeditor/test/browser_callwatcher-01.js
index ade42bd248c0..11c3ad11c5e3 100644
--- a/devtools/client/webaudioeditor/test/browser_callwatcher-01.js
+++ b/devtools/client/webaudioeditor/test/browser_callwatcher-01.js
@@ -10,17 +10,17 @@
 
 const BUG_1130901_URL = EXAMPLE_URL + "doc_bug_1130901.html";
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(BUG_1130901_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(BUG_1130901_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
   let rendered = waitForGraphRendered(panelWin, 3, 0);
   reload(target);
-  await rendered;
+  yield rendered;
 
   ok(true, "Successfully created a node from AudioContext via `call`.");
   ok(true, "Successfully created a node from AudioContext via `apply`.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_callwatcher-02.js b/devtools/client/webaudioeditor/test/browser_callwatcher-02.js
index a89a04537ef7..c65ad7f7c8a7 100644
--- a/devtools/client/webaudioeditor/test/browser_callwatcher-02.js
+++ b/devtools/client/webaudioeditor/test/browser_callwatcher-02.js
@@ -9,8 +9,8 @@
 
 const BUG_1112378_URL = EXAMPLE_URL + "doc_bug_1112378.html";
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(BUG_1112378_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(BUG_1112378_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
@@ -18,9 +18,9 @@ add_task(async function () {
 
   let rendered = waitForGraphRendered(panelWin, 2, 0);
   reload(target);
-  await rendered;
+  yield rendered;
 
-  let error = await evalInDebuggee("throwError()");
+  let error = yield evalInDebuggee("throwError()");
   is(error.lineNumber, 21, "error has correct lineNumber");
   is(error.columnNumber, 11, "error has correct columnNumber");
   is(error.name, "TypeError", "error has correct name");
@@ -29,7 +29,7 @@ add_task(async function () {
   is(error.instanceof, true, "error is correctly an instanceof TypeError");
   is(error.fileName, "http://example.com/browser/devtools/client/webaudioeditor/test/doc_bug_1112378.html", "error has correct fileName");
 
-  error = await evalInDebuggee("throwDOMException()");
+  error = yield evalInDebuggee("throwDOMException()");
   is(error.lineNumber, 37, "exception has correct lineNumber");
   is(error.columnNumber, 0, "exception has correct columnNumber");
   is(error.code, 9, "exception has correct code");
@@ -40,5 +40,5 @@ add_task(async function () {
   is(error.instanceof, true, "exception is correctly an instance of DOMException");
   is(error.filename, "http://example.com/browser/devtools/client/webaudioeditor/test/doc_bug_1112378.html", "exception has correct filename");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_automation-view-01.js b/devtools/client/webaudioeditor/test/browser_wa_automation-view-01.js
index 14e87cce5fa9..1e0034b5b6d1 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_automation-view-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_automation-view-01.js
@@ -6,8 +6,8 @@
  * or params exist.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(AUTOMATION_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(AUTOMATION_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS } = panelWin;
 
@@ -18,14 +18,14 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   let $tabbox = $("#web-audio-editor-tabs");
 
   // Oscillator node
   click(panelWin, findGraphNode(panelWin, nodeIds[1]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
   $tabbox.selectedIndex = 1;
 
   ok(isVisible($("#automation-graph-container")), "graph container should be visible");
@@ -35,7 +35,7 @@ add_task(async function () {
 
   // Gain node
   click(panelWin, findGraphNode(panelWin, nodeIds[2]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
   $tabbox.selectedIndex = 1;
 
   ok(!isVisible($("#automation-graph-container")), "graph container should not be visible");
@@ -45,7 +45,7 @@ add_task(async function () {
 
   // destination node
   click(panelWin, findGraphNode(panelWin, nodeIds[0]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
   $tabbox.selectedIndex = 1;
 
   ok(!isVisible($("#automation-graph-container")), "graph container should not be visible");
@@ -53,5 +53,5 @@ add_task(async function () {
   ok(!isVisible($("#automation-no-events")), "no-events panel should not be visible");
   ok(isVisible($("#automation-empty")), "empty panel should be visible");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_automation-view-02.js b/devtools/client/webaudioeditor/test/browser_wa_automation-view-02.js
index 61b709a40639..a0f5f5a04e76 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_automation-view-02.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_automation-view-02.js
@@ -6,8 +6,8 @@
  * switching between AudioParam rerenders the graph.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(AUTOMATION_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(AUTOMATION_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, AutomationView } = panelWin;
 
@@ -18,12 +18,12 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   // Oscillator node
   click(panelWin, findGraphNode(panelWin, nodeIds[1]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
   click(panelWin, $("#automation-tab"));
 
   ok(AutomationView._selectedParamName, "frequency",
@@ -37,7 +37,7 @@ add_task(async function () {
   ok(!isVisible($("#automation-no-events")), "no-events panel should not be visible");
 
   click(panelWin, $(".automation-param-button[data-param='detune']"));
-  await once(panelWin, EVENTS.UI_AUTOMATION_TAB_RENDERED);
+  yield once(panelWin, EVENTS.UI_AUTOMATION_TAB_RENDERED);
 
   ok(true, "automation tab rerendered");
 
@@ -51,5 +51,5 @@ add_task(async function () {
   ok(!isVisible($("#automation-graph-container")), "graph container should not be visible");
   ok(isVisible($("#automation-no-events")), "no-events panel should be visible");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_controller-01.js b/devtools/client/webaudioeditor/test/browser_wa_controller-01.js
index 0b04c894f058..a7064df1f29a 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_controller-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_controller-01.js
@@ -9,8 +9,8 @@
 
 const BUG_1125817_URL = EXAMPLE_URL + "doc_bug_1125817.html";
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(BUG_1125817_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(BUG_1125817_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
@@ -20,9 +20,9 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 2, 0)
   ]);
   reload(target);
-  await events;
+  yield events;
 
   ok(true, "Successfully disconnected a just-created node.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_destroy-node-01.js b/devtools/client/webaudioeditor/test/browser_wa_destroy-node-01.js
index 1a15a73f9708..d7dde4d97f3f 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_destroy-node-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_destroy-node-01.js
@@ -9,8 +9,8 @@
  * All done in one test since this test takes a few seconds to clear GC.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(DESTROY_NODES_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(DESTROY_NODES_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, gAudioNodes } = panelWin;
 
@@ -21,14 +21,14 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 13, 2)
   ]);
   reload(target);
-  let [created] = await events;
+  let [created] = yield events;
 
   // Flatten arrays of event arguments and take the first (AudioNodeModel)
   // and get its ID.
   let actorIDs = created.map(ev => ev[0].id);
 
   // Click a soon-to-be dead buffer node
-  await clickGraphNode(panelWin, actorIDs[5]);
+  yield clickGraphNode(panelWin, actorIDs[5]);
 
   let destroyed = getN(gAudioNodes, "remove", 10);
 
@@ -36,7 +36,7 @@ add_task(async function () {
   forceNodeCollection();
 
   // Wait for destruction and graph to re-render
-  await Promise.all([destroyed, waitForGraphRendered(panelWin, 3, 2)]);
+  yield Promise.all([destroyed, waitForGraphRendered(panelWin, 3, 2)]);
 
   // Test internal storage
   is(panelWin.gAudioNodes.length, 3, "All nodes should be GC'd except one gain, osc and dest node.");
@@ -55,5 +55,5 @@ add_task(async function () {
   ok(isVisible($("#web-audio-editor-details-pane-empty")),
     "InspectorView empty message should show if the currently selected node gets collected.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_first-run.js b/devtools/client/webaudioeditor/test/browser_wa_first-run.js
index cdc169370eaf..76db921ba10d 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_first-run.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_first-run.js
@@ -5,8 +5,8 @@
  * Tests that the reloading/onContentLoaded hooks work.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { gFront, $ } = panel.panelWin;
 
   is($("#reload-notice").hidden, false,
@@ -21,7 +21,7 @@ add_task(async function () {
 
   reload(target);
 
-  await navigating;
+  yield navigating;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden when navigating.");
@@ -30,7 +30,7 @@ add_task(async function () {
   is($("#content").hidden, true,
     "The tool's content should still be hidden.");
 
-  await started;
+  yield started;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden after context found.");
@@ -39,5 +39,5 @@ add_task(async function () {
   is($("#content").hidden, false,
     "The tool's content should not be hidden anymore.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-click.js b/devtools/client/webaudioeditor/test/browser_wa_graph-click.js
index ad3cc3371dbe..b075d30db490 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-click.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-click.js
@@ -6,8 +6,8 @@
  * the correct node in the InspectorView
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(COMPLEX_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(COMPLEX_CONTEXT_URL);
   let panelWin = panel.panelWin;
   let { gFront, $, $$, InspectorView } = panelWin;
 
@@ -18,32 +18,32 @@ add_task(async function () {
     waitForGraphRendered(panel.panelWin, 8, 8)
   ]);
   reload(target);
-  let [actors, _] = await events;
+  let [actors, _] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   ok(!InspectorView.isVisible(), "InspectorView hidden on start.");
 
-  await clickGraphNode(panelWin, nodeIds[1], true);
+  yield clickGraphNode(panelWin, nodeIds[1], true);
 
   ok(InspectorView.isVisible(), "InspectorView visible after selecting a node.");
   is(InspectorView.getCurrentAudioNode().id, nodeIds[1], "InspectorView has correct node set.");
 
-  await clickGraphNode(panelWin, nodeIds[2]);
+  yield clickGraphNode(panelWin, nodeIds[2]);
 
   ok(InspectorView.isVisible(), "InspectorView still visible after selecting another node.");
   is(InspectorView.getCurrentAudioNode().id, nodeIds[2], "InspectorView has correct node set on second node.");
 
-  await clickGraphNode(panelWin, nodeIds[2]);
+  yield clickGraphNode(panelWin, nodeIds[2]);
   is(InspectorView.getCurrentAudioNode().id, nodeIds[2], "Clicking the same node again works (idempotent).");
 
-  await clickGraphNode(panelWin, $("rect", findGraphNode(panelWin, nodeIds[3])));
+  yield clickGraphNode(panelWin, $("rect", findGraphNode(panelWin, nodeIds[3])));
   is(InspectorView.getCurrentAudioNode().id, nodeIds[3], "Clicking on a <rect> works as expected.");
 
-  await clickGraphNode(panelWin, $("tspan", findGraphNode(panelWin, nodeIds[4])));
+  yield clickGraphNode(panelWin, $("tspan", findGraphNode(panelWin, nodeIds[4])));
   is(InspectorView.getCurrentAudioNode().id, nodeIds[4], "Clicking on a <tspan> works as expected.");
 
   ok(InspectorView.isVisible(),
     "InspectorView still visible after several nodes have been clicked.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-markers.js b/devtools/client/webaudioeditor/test/browser_wa_graph-markers.js
index 3af4bc9d3087..adc15d0c31e0 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-markers.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-markers.js
@@ -7,8 +7,8 @@
 
 const { setTheme } = require("devtools/client/shared/theme");
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, MARKER_STYLING } = panelWin;
 
@@ -24,7 +24,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
 
   is(getFill($("#arrowhead")), MARKER_STYLING[currentTheme],
     "marker initially matches theme.");
@@ -49,7 +49,7 @@ add_task(async function () {
   is(getFill($("#arrowhead")), MARKER_STYLING.light,
     "marker styling switches back to light once again.");
 
-  await teardown(target);
+  yield teardown(target);
 });
 
 /**
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-render-01.js b/devtools/client/webaudioeditor/test/browser_wa_graph-render-01.js
index 2df2af698209..cee1987b9368 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-render-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-render-01.js
@@ -7,8 +7,8 @@
 
 var connectCount = 0;
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
@@ -21,7 +21,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let [destId, oscId, gainId] = actors.map(actor => actor.actorID);
 
   ok(findGraphNode(panelWin, oscId).classList.contains("type-OscillatorNode"), "found OscillatorNode with class");
@@ -30,13 +30,13 @@ add_task(async function () {
   is(findGraphEdge(panelWin, oscId, gainId).toString(), "[object SVGGElement]", "found edge for osc -> gain");
   is(findGraphEdge(panelWin, gainId, destId).toString(), "[object SVGGElement]", "found edge for gain -> dest");
 
-  await wait(1000);
+  yield wait(1000);
 
   is(connectCount, 2, "Only two node connect events should be fired.");
 
   gAudioNodes.off("connect", onConnectNode);
 
-  await teardown(target);
+  yield teardown(target);
 });
 
 function onConnectNode() {
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-render-02.js b/devtools/client/webaudioeditor/test/browser_wa_graph-render-02.js
index 6d39300495b8..00a63c6b2bee 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-render-02.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-render-02.js
@@ -5,8 +5,8 @@
  * Tests more edge rendering for complex graphs.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(COMPLEX_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(COMPLEX_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$ } = panelWin;
 
@@ -17,7 +17,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 8, 8)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIDs = actors.map(actor => actor.actorID);
 
   let types = ["AudioDestinationNode", "OscillatorNode", "GainNode", "ScriptProcessorNode",
@@ -44,5 +44,5 @@ add_task(async function () {
       "found edge for " + msg);
   });
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-render-03.js b/devtools/client/webaudioeditor/test/browser_wa_graph-render-03.js
index 07a63a836bc2..ffd9b9881c6e 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-render-03.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-render-03.js
@@ -5,8 +5,8 @@
  * Tests to ensure that selected nodes stay selected on graph redraw.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS } = panelWin;
 
@@ -15,20 +15,20 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let [dest, osc, gain] = actors;
 
-  await clickGraphNode(panelWin, gain.actorID);
+  yield clickGraphNode(panelWin, gain.actorID);
   ok(findGraphNode(panelWin, gain.actorID).classList.contains("selected"),
     "Node selected once.");
 
   // Disconnect a node to trigger a rerender
   osc.disconnect();
 
-  await once(panelWin, EVENTS.UI_GRAPH_RENDERED);
+  yield once(panelWin, EVENTS.UI_GRAPH_RENDERED);
 
   ok(findGraphNode(panelWin, gain.actorID).classList.contains("selected"),
     "Node still selected after rerender.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-render-04.js b/devtools/client/webaudioeditor/test/browser_wa_graph-render-04.js
index 9643cb1c7c7f..9ed3ceffd42a 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-render-04.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-render-04.js
@@ -5,8 +5,8 @@
  * Tests audio param connection rendering.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(CONNECT_MULTI_PARAM_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(CONNECT_MULTI_PARAM_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS } = panelWin;
 
@@ -17,7 +17,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 5, 2, 3)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIDs = actors.map(actor => actor.actorID);
 
   let [, carrier, gain, mod1, mod2] = nodeIDs;
@@ -33,5 +33,5 @@ add_task(async function () {
     ok(edge.classList.contains("param-connection"), "edge is classified as a param-connection");
   });
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-render-05.js b/devtools/client/webaudioeditor/test/browser_wa_graph-render-05.js
index 5330bc8b3fb2..2748984d0264 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-render-05.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-render-05.js
@@ -5,8 +5,8 @@
  * Tests to ensure that param connections trigger graph redraws
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS } = panelWin;
 
@@ -15,14 +15,14 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2, 0)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let [dest, osc, gain] = actors;
 
-  await osc.disconnect();
+  yield osc.disconnect();
 
   osc.connectParam(gain, "gain");
-  await waitForGraphRendered(panelWin, 3, 1, 1);
+  yield waitForGraphRendered(panelWin, 3, 1, 1);
   ok(true, "Graph re-rendered upon param connection");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-render-06.js b/devtools/client/webaudioeditor/test/browser_wa_graph-render-06.js
index 24fb4cf514c3..c47d60b7c2de 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-render-06.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-render-06.js
@@ -7,8 +7,8 @@
 
 const BUG_1141261_URL = EXAMPLE_URL + "doc_bug_1141261.html";
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(BUG_1141261_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(BUG_1141261_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS } = panelWin;
 
@@ -17,9 +17,9 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 1, 0)
   ]);
   reload(target);
-  await events;
+  yield events;
 
   ok(true, "Graph correctly shows gain node as disconnected");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-selected.js b/devtools/client/webaudioeditor/test/browser_wa_graph-selected.js
index f623caf42623..72044b7bd7ae 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-selected.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-selected.js
@@ -5,8 +5,8 @@
  * Tests that SVG nodes and edges were created for the Graph View.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS } = panelWin;
 
@@ -17,7 +17,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let [destId, oscId, gainId] = actors.map(actor => actor.actorID);
 
   ok(!findGraphNode(panelWin, destId).classList.contains("selected"),
@@ -27,7 +27,7 @@ add_task(async function () {
   ok(!findGraphNode(panelWin, gainId).classList.contains("selected"),
     "No nodes selected on start. (gain)");
 
-  await clickGraphNode(panelWin, oscId);
+  yield clickGraphNode(panelWin, oscId);
 
   ok(findGraphNode(panelWin, oscId).classList.contains("selected"),
     "Selected node has class 'selected'.");
@@ -36,7 +36,7 @@ add_task(async function () {
   ok(!findGraphNode(panelWin, gainId).classList.contains("selected"),
     "Non-selected nodes do not have class 'selected'.");
 
-  await clickGraphNode(panelWin, gainId);
+  yield clickGraphNode(panelWin, gainId);
 
   ok(!findGraphNode(panelWin, oscId).classList.contains("selected"),
     "Previously selected node no longer has class 'selected'.");
@@ -45,5 +45,5 @@ add_task(async function () {
   ok(findGraphNode(panelWin, gainId).classList.contains("selected"),
     "Newly selected node now has class 'selected'.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_graph-zoom.js b/devtools/client/webaudioeditor/test/browser_wa_graph-zoom.js
index 554465412601..240b6d5a141e 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_graph-zoom.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_graph-zoom.js
@@ -5,14 +5,14 @@
  * Tests that the graph's scale and position is reset on a page reload.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, ContextView } = panelWin;
 
   let started = once(gFront, "start-context");
 
-  await Promise.all([
+  yield Promise.all([
     waitForGraphRendered(panelWin, 3, 2),
     reload(target),
   ]);
@@ -30,7 +30,7 @@ add_task(async function () {
   is(ContextView.getCurrentTranslation()[0], 100, "After zoom, x-translation is 100.");
   is(ContextView.getCurrentTranslation()[1], 400, "After zoom, y-translation is 400.");
 
-  await Promise.all([
+  yield Promise.all([
     waitForGraphRendered(panelWin, 3, 2),
     reload(target),
   ]);
@@ -39,5 +39,5 @@ add_task(async function () {
   is(ContextView.getCurrentTranslation()[0], 20, "After refresh, x-translation is 20.");
   is(ContextView.getCurrentTranslation()[1], 20, "After refresh, y-translation is 20.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_inspector-bypass-01.js b/devtools/client/webaudioeditor/test/browser_wa_inspector-bypass-01.js
index 92c2e773788e..c9d3450e38d8 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_inspector-bypass-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_inspector-bypass-01.js
@@ -5,8 +5,8 @@
  * Tests that nodes are correctly bypassed when bypassing.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, gAudioNodes } = panelWin;
 
@@ -15,47 +15,47 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   // Wait for the node to be set as well as the inspector to come fully into the view
-  await clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]), true);
+  yield clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]), true);
 
   let $bypass = $("toolbarbutton.bypass");
 
-  is((await actors[1].isBypassed()), false, "AudioNodeActor is not bypassed by default.");
+  is((yield actors[1].isBypassed()), false, "AudioNodeActor is not bypassed by default.");
   is($bypass.checked, true, "Button is 'on' for normal nodes");
   is($bypass.disabled, false, "Bypass button is not disabled for normal nodes");
 
   command($bypass);
-  await once(gAudioNodes, "bypass");
+  yield once(gAudioNodes, "bypass");
 
-  is((await actors[1].isBypassed()), true, "AudioNodeActor is bypassed.");
+  is((yield actors[1].isBypassed()), true, "AudioNodeActor is bypassed.");
   is($bypass.checked, false, "Button is 'off' when clicked");
   is($bypass.disabled, false, "Bypass button is not disabled after click");
   ok(findGraphNode(panelWin, nodeIds[1]).classList.contains("bypassed"),
     "AudioNode has 'bypassed' class.");
 
   command($bypass);
-  await once(gAudioNodes, "bypass");
+  yield once(gAudioNodes, "bypass");
 
-  is((await actors[1].isBypassed()), false, "AudioNodeActor is no longer bypassed.");
+  is((yield actors[1].isBypassed()), false, "AudioNodeActor is no longer bypassed.");
   is($bypass.checked, true, "Button is back on when clicked");
   is($bypass.disabled, false, "Bypass button is not disabled after click");
   ok(!findGraphNode(panelWin, nodeIds[1]).classList.contains("bypassed"),
     "AudioNode no longer has 'bypassed' class.");
 
-  await clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[0]));
+  yield clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[0]));
 
-  is((await actors[0].isBypassed()), false, "Unbypassable AudioNodeActor is not bypassed.");
+  is((yield actors[0].isBypassed()), false, "Unbypassable AudioNodeActor is not bypassed.");
   is($bypass.checked, false, "Button is 'off' for unbypassable nodes");
   is($bypass.disabled, true, "Bypass button is disabled for unbypassable nodes");
 
   command($bypass);
-  is((await actors[0].isBypassed()), false,
+  is((yield actors[0].isBypassed()), false,
     "Clicking button on unbypassable node does not change bypass state on actor.");
   is($bypass.checked, false, "Button is still 'off' for unbypassable nodes");
   is($bypass.disabled, true, "Bypass button is still disabled for unbypassable nodes");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_inspector-toggle.js b/devtools/client/webaudioeditor/test/browser_wa_inspector-toggle.js
index 935ed271b873..251f92471fbb 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_inspector-toggle.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_inspector-toggle.js
@@ -6,8 +6,8 @@
  * the inspector panel as intended.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, InspectorView } = panelWin;
   let gVars = InspectorView._propsView;
@@ -19,14 +19,14 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   ok(!InspectorView.isVisible(), "InspectorView hidden on start.");
 
   // Open inspector pane
   $("#inspector-pane-toggle").click();
-  await once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
+  yield once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
 
   ok(InspectorView.isVisible(), "InspectorView shown after toggling.");
 
@@ -37,24 +37,24 @@ add_task(async function () {
 
   // Close inspector pane
   $("#inspector-pane-toggle").click();
-  await once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
+  yield once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
 
   ok(!InspectorView.isVisible(), "InspectorView back to being hidden.");
 
   // Open again to test node loading while open
   $("#inspector-pane-toggle").click();
-  await once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
+  yield once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
 
   ok(InspectorView.isVisible(), "InspectorView being shown.");
   ok(!isVisible($("#web-audio-editor-tabs")),
     "InspectorView tabs are still hidden.");
 
-  await clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]));
+  yield clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]));
 
   ok(!isVisible($("#web-audio-editor-details-pane-empty")),
     "Empty message hides even when loading node while open.");
   ok(isVisible($("#web-audio-editor-tabs")),
     "Switches to tab view when loading node while open.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_inspector-width.js b/devtools/client/webaudioeditor/test/browser_wa_inspector-width.js
index 4d7ceae97a90..d37774013d0a 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_inspector-width.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_inspector-width.js
@@ -6,8 +6,8 @@
  * a preference
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, InspectorView } = panelWin;
   let gVars = InspectorView._propsView;
@@ -19,14 +19,14 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   ok(!InspectorView.isVisible(), "InspectorView hidden on start.");
 
   // Open inspector pane
   $("#inspector-pane-toggle").click();
-  await once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
+  yield once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
 
   let newInspectorWidth = 500;
 
@@ -39,19 +39,19 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  [actors] = await events;
+  [actors] = yield events;
   nodeIds = actors.map(actor => actor.actorID);
 
   // Open inspector pane
   $("#inspector-pane-toggle").click();
-  await once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
+  yield once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED);
 
-  await clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]));
+  yield clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]));
 
   // Getting the width of the audio inspector
   let width = $("#web-audio-inspector").getAttribute("width");
 
   is(width, newInspectorWidth, "WebAudioEditor's Inspector width should be saved as a preference");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_inspector.js b/devtools/client/webaudioeditor/test/browser_wa_inspector.js
index 56b231489d64..5599ad36fb84 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_inspector.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_inspector.js
@@ -6,8 +6,8 @@
  * loads the correct node inside the inspector.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, InspectorView } = panelWin;
   let gVars = InspectorView._propsView;
@@ -19,7 +19,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   ok(!InspectorView.isVisible(), "InspectorView hidden on start.");
@@ -29,7 +29,7 @@ add_task(async function () {
     "InspectorView tabs view should be hidden when no node's selected.");
 
   // Wait for the node to be set as well as the inspector to come fully into the view
-  await clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]), true);
+  yield clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[1]), true);
 
   ok(InspectorView.isVisible(), "InspectorView shown once node selected.");
   ok(!isVisible($("#web-audio-editor-details-pane-empty")),
@@ -40,7 +40,7 @@ add_task(async function () {
   is($("#web-audio-editor-tabs").selectedIndex, 0,
     "default tab selected should be the parameters tab.");
 
-  await clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[2]));
+  yield clickGraphNode(panelWin, findGraphNode(panelWin, nodeIds[2]));
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_navigate.js b/devtools/client/webaudioeditor/test/browser_wa_navigate.js
index 977415050b7f..e1f0943848ca 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_navigate.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_navigate.js
@@ -6,8 +6,8 @@
  * the audio graph if both pages have an AudioContext.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $ } = panelWin;
 
@@ -16,7 +16,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  await events;
+  yield events;
 
   var { nodes, edges } = countGraphObjects(panelWin);
   is(nodes, 3, "should only be 3 nodes.");
@@ -27,7 +27,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 15, 0)
   ]);
   navigate(target, SIMPLE_NODES_URL);
-  await events;
+  yield events;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden after context found after navigation.");
@@ -40,5 +40,5 @@ add_task(async function () {
   is(nodes, 15, "after navigation, should have 15 nodes");
   is(edges, 0, "after navigation, should have 0 edges.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-01.js b/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-01.js
index 46b722a75148..ac7deca26cbb 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-01.js
@@ -5,8 +5,8 @@
  * Tests that properties are updated when modifying the VariablesView.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, PropertiesView } = panelWin;
   let gVars = PropertiesView._propsView;
@@ -18,12 +18,12 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   click(panelWin, findGraphNode(panelWin, nodeIds[1]));
   // Wait for the node to be set as well as the inspector to come fully into the view
-  await Promise.all([
+  yield Promise.all([
     waitForInspectorRender(panelWin, EVENTS),
     once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED)
   ]);
@@ -37,29 +37,29 @@ add_task(async function () {
   }, "default loaded string");
 
   click(panelWin, findGraphNode(panelWin, nodeIds[2]));
-  await waitForInspectorRender(panelWin, EVENTS),
+  yield waitForInspectorRender(panelWin, EVENTS),
   checkVariableView(gVars, 0, {
     "gain": 0
   }, "default loaded number");
 
   click(panelWin, findGraphNode(panelWin, nodeIds[1]));
-  await waitForInspectorRender(panelWin, EVENTS),
-  await setAndCheck(0, "type", "square", "square", "sets string as string");
+  yield waitForInspectorRender(panelWin, EVENTS),
+  yield setAndCheck(0, "type", "square", "square", "sets string as string");
 
   click(panelWin, findGraphNode(panelWin, nodeIds[2]));
-  await waitForInspectorRender(panelWin, EVENTS),
-  await setAndCheck(0, "gain", "0.005", 0.005, "sets number as number");
-  await setAndCheck(0, "gain", "0.1", 0.1, "sets float as float");
-  await setAndCheck(0, "gain", ".2", 0.2, "sets float without leading zero as float");
+  yield waitForInspectorRender(panelWin, EVENTS),
+  yield setAndCheck(0, "gain", "0.005", 0.005, "sets number as number");
+  yield setAndCheck(0, "gain", "0.1", 0.1, "sets float as float");
+  yield setAndCheck(0, "gain", ".2", 0.2, "sets float without leading zero as float");
 
-  await teardown(target);
+  yield teardown(target);
 });
 
 function setAndCheckVariable(panelWin, gVars) {
-  return async function (varNum, prop, value, expected, desc) {
-    await modifyVariableView(panelWin, gVars, varNum, prop, value);
+  return Task.async(function* (varNum, prop, value, expected, desc) {
+    yield modifyVariableView(panelWin, gVars, varNum, prop, value);
     var props = {};
     props[prop] = expected;
     checkVariableView(gVars, varNum, props, desc);
-  };
+  });
 }
diff --git a/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-02.js b/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-02.js
index 6f89e4329ec6..d7c54822da12 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-02.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_properties-view-edit-02.js
@@ -5,8 +5,8 @@
  * Tests that properties are not updated when modifying the VariablesView.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(COMPLEX_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(COMPLEX_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, PropertiesView } = panelWin;
   let gVars = PropertiesView._propsView;
@@ -18,12 +18,12 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 8, 8)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   click(panelWin, findGraphNode(panelWin, nodeIds[3]));
   // Wait for the node to be set as well as the inspector to come fully into the view
-  await Promise.all([
+  yield Promise.all([
     waitForInspectorRender(panelWin, EVENTS),
     once(panelWin, EVENTS.UI_INSPECTOR_TOGGLED),
   ]);
@@ -31,14 +31,14 @@ add_task(async function () {
   let errorEvent = once(panelWin, EVENTS.UI_SET_PARAM_ERROR);
 
   try {
-    await modifyVariableView(panelWin, gVars, 0, "bufferSize", 2048);
+    yield modifyVariableView(panelWin, gVars, 0, "bufferSize", 2048);
   } catch (e) {
     // we except modifyVariableView to fail here, because bufferSize is not writable
   }
 
-  await errorEvent;
+  yield errorEvent;
 
   checkVariableView(gVars, 0, {bufferSize: 4096}, "check that unwritable variable is not updated");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_properties-view-media-nodes.js b/devtools/client/webaudioeditor/test/browser_wa_properties-view-media-nodes.js
index 7dda65f843d5..959fb9535843 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_properties-view-media-nodes.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_properties-view-media-nodes.js
@@ -32,8 +32,8 @@ function waitForDeviceClosed() {
   });
 }
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(MEDIA_NODES_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(MEDIA_NODES_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, PropertiesView } = panelWin;
   let gVars = PropertiesView._propsView;
@@ -42,14 +42,14 @@ add_task(async function () {
   let mediaPermissionPref = Services.prefs.getBoolPref(MEDIA_PERMISSION);
   Services.prefs.setBoolPref(MEDIA_PERMISSION, true);
 
-  await loadFrameScriptUtils();
+  yield loadFrameScriptUtils();
 
   let events = Promise.all([
     getN(gFront, "create-node", 4),
     waitForGraphRendered(panelWin, 4, 0)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   let types = [
@@ -57,18 +57,18 @@ add_task(async function () {
     "MediaStreamAudioSourceNode", "MediaStreamAudioDestinationNode"
   ];
 
-  let defaults = await Promise.all(types.map(type => nodeDefaultValues(type)));
+  let defaults = yield Promise.all(types.map(type => nodeDefaultValues(type)));
 
   for (let i = 0; i < types.length; i++) {
     click(panelWin, findGraphNode(panelWin, nodeIds[i]));
-    await waitForInspectorRender(panelWin, EVENTS);
+    yield waitForInspectorRender(panelWin, EVENTS);
     checkVariableView(gVars, 0, defaults[i], types[i]);
   }
 
   // Reset permissions on getUserMedia
   Services.prefs.setBoolPref(MEDIA_PERMISSION, mediaPermissionPref);
 
-  await teardown(target);
+  yield teardown(target);
 
-  await waitForDeviceClosed();
+  yield waitForDeviceClosed();
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_properties-view-params-objects.js b/devtools/client/webaudioeditor/test/browser_wa_properties-view-params-objects.js
index 1ca036088bea..e0a555201e06 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_properties-view-params-objects.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_properties-view-params-objects.js
@@ -6,8 +6,8 @@
  * like AudioBuffer and Float32Array in properties of AudioNodes.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(BUFFER_AND_ARRAY_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(BUFFER_AND_ARRAY_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, PropertiesView } = panelWin;
   let gVars = PropertiesView._propsView;
@@ -19,11 +19,11 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   click(panelWin, findGraphNode(panelWin, nodeIds[2]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
   checkVariableView(gVars, 0, {
     "curve": "Float32Array"
   }, "WaveShaper's `curve` is listed as an `Float32Array`.");
@@ -33,7 +33,7 @@ add_task(async function () {
   ok(state, "Float32Array property should not have a dropdown.");
 
   click(panelWin, findGraphNode(panelWin, nodeIds[1]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
   checkVariableView(gVars, 0, {
     "buffer": "AudioBuffer"
   }, "AudioBufferSourceNode's `buffer` is listed as an `AudioBuffer`.");
@@ -42,5 +42,5 @@ add_task(async function () {
   state = aVar.target.querySelector(".theme-twisty").hasAttribute("invisible");
   ok(state, "AudioBuffer property should not have a dropdown.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_properties-view-params.js b/devtools/client/webaudioeditor/test/browser_wa_properties-view-params.js
index 85dde6c1dc60..5881c6d4be48 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_properties-view-params.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_properties-view-params.js
@@ -6,22 +6,22 @@
  * correctly, with default values and correct types.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_NODES_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_NODES_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, PropertiesView } = panelWin;
   let gVars = PropertiesView._propsView;
 
   let started = once(gFront, "start-context");
 
-  await loadFrameScriptUtils();
+  yield loadFrameScriptUtils();
 
   let events = Promise.all([
     getN(gFront, "create-node", 15),
     waitForGraphRendered(panelWin, 15, 0)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   let types = [
@@ -31,13 +31,13 @@ add_task(async function () {
     "DynamicsCompressorNode", "OscillatorNode"
   ];
 
-  let defaults = await Promise.all(types.map(type => nodeDefaultValues(type)));
+  let defaults = yield Promise.all(types.map(type => nodeDefaultValues(type)));
 
   for (let i = 0; i < types.length; i++) {
     click(panelWin, findGraphNode(panelWin, nodeIds[i]));
-    await waitForInspectorRender(panelWin, EVENTS);
+    yield waitForInspectorRender(panelWin, EVENTS);
     checkVariableView(gVars, 0, defaults[i], types[i]);
   }
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_properties-view.js b/devtools/client/webaudioeditor/test/browser_wa_properties-view.js
index 64a0940bdbfd..bda51e4ac0ba 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_properties-view.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_properties-view.js
@@ -5,8 +5,8 @@
  * Tests that params view shows params when they exist, and are hidden otherwise.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, $$, EVENTS, PropertiesView } = panelWin;
   let gVars = PropertiesView._propsView;
@@ -18,12 +18,12 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
   // Gain node
   click(panelWin, findGraphNode(panelWin, nodeIds[2]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
 
   ok(isVisible($("#properties-content")), "Parameters shown when they exist.");
   ok(!isVisible($("#properties-empty")),
@@ -31,12 +31,12 @@ add_task(async function () {
 
   // Destination node
   click(panelWin, findGraphNode(panelWin, nodeIds[0]));
-  await waitForInspectorRender(panelWin, EVENTS);
+  yield waitForInspectorRender(panelWin, EVENTS);
 
   ok(!isVisible($("#properties-content")),
     "Parameters hidden when they don't exist.");
   ok(isVisible($("#properties-empty")),
     "Empty message shown when no AudioParams exist.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_reset-01.js b/devtools/client/webaudioeditor/test/browser_wa_reset-01.js
index 46fde7c893e1..2afe614d306a 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_reset-01.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_reset-01.js
@@ -6,8 +6,8 @@
  * event and reshow the tools after reloading.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { gFront, $ } = panel.panelWin;
 
   is($("#reload-notice").hidden, false,
@@ -22,7 +22,7 @@ add_task(async function () {
 
   reload(target);
 
-  await navigating;
+  yield navigating;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden when navigating.");
@@ -31,7 +31,7 @@ add_task(async function () {
   is($("#content").hidden, true,
     "The tool's content should still be hidden.");
 
-  await started;
+  yield started;
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden after context found.");
@@ -45,7 +45,7 @@ add_task(async function () {
 
   reload(target);
 
-  await Promise.all([navigating, started]);
+  yield Promise.all([navigating, started]);
   let rendered = waitForGraphRendered(panel.panelWin, 3, 2);
 
   is($("#reload-notice").hidden, true,
@@ -55,7 +55,7 @@ add_task(async function () {
   is($("#content").hidden, false,
     "The tool's content should reappear without closing and reopening the toolbox.");
 
-  await rendered;
+  yield rendered;
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_reset-02.js b/devtools/client/webaudioeditor/test/browser_wa_reset-02.js
index bcf0d1c5d9b8..c9516b364c9b 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_reset-02.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_reset-02.js
@@ -6,8 +6,8 @@
  * the graph.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $ } = panelWin;
 
@@ -16,7 +16,7 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  await events;
+  yield events;
 
   let { nodes, edges } = countGraphObjects(panelWin);
   is(nodes, 3, "should only be 3 nodes.");
@@ -27,11 +27,11 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  await events;
+  yield events;
 
   ({ nodes, edges } = countGraphObjects(panelWin));
   is(nodes, 3, "after reload, should only be 3 nodes.");
   is(edges, 2, "after reload, should only be 2 edges.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_reset-03.js b/devtools/client/webaudioeditor/test/browser_wa_reset-03.js
index fd391e81495a..1207793f58a2 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_reset-03.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_reset-03.js
@@ -6,8 +6,8 @@
  * the inspector and selected node.
  */
 
-add_task(async function () {
-  let { target, panel } = await initWebAudioEditor(SIMPLE_CONTEXT_URL);
+add_task(function* () {
+  let { target, panel } = yield initWebAudioEditor(SIMPLE_CONTEXT_URL);
   let { panelWin } = panel;
   let { gFront, $, InspectorView } = panelWin;
 
@@ -16,10 +16,10 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  let [actors] = await events;
+  let [actors] = yield events;
   let nodeIds = actors.map(actor => actor.actorID);
 
-  await clickGraphNode(panelWin, nodeIds[1], true);
+  yield clickGraphNode(panelWin, nodeIds[1], true);
   ok(InspectorView.isVisible(), "InspectorView visible after selecting a node.");
   is(InspectorView.getCurrentAudioNode().id, nodeIds[1], "InspectorView has correct node set.");
 
@@ -32,17 +32,17 @@ add_task(async function () {
     waitForGraphRendered(panelWin, 3, 2)
   ]);
   reload(target);
-  [actors] = await events;
+  [actors] = yield events;
   nodeIds = actors.map(actor => actor.actorID);
 
   ok(!InspectorView.isVisible(), "InspectorView hidden on start.");
   is(InspectorView.getCurrentAudioNode(), null,
     "InspectorView has no current node set on reset.");
 
-  await clickGraphNode(panelWin, nodeIds[2], true);
+  yield clickGraphNode(panelWin, nodeIds[2], true);
   ok(InspectorView.isVisible(),
     "InspectorView visible after selecting a node after a reset.");
   is(InspectorView.getCurrentAudioNode().id, nodeIds[2], "InspectorView has correct node set upon clicking graph node after a reset.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_wa_reset-04.js b/devtools/client/webaudioeditor/test/browser_wa_reset-04.js
index 8f12c3bf6140..84d5df7f768a 100644
--- a/devtools/client/webaudioeditor/test/browser_wa_reset-04.js
+++ b/devtools/client/webaudioeditor/test/browser_wa_reset-04.js
@@ -5,10 +5,10 @@
  * Tests that switching to an iframe works fine.
  */
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setBoolPref("devtools.command-button-frames.enabled", true);
 
-  let { target, panel, toolbox } = await initWebAudioEditor(IFRAME_CONTEXT_URL);
+  let { target, panel, toolbox } = yield initWebAudioEditor(IFRAME_CONTEXT_URL);
   let { gFront, $ } = panel.panelWin;
 
   is($("#reload-notice").hidden, false,
@@ -22,8 +22,8 @@ add_task(async function () {
   ok(!btn.firstChild, "The frame list button has no children");
 
   // Open frame menu and wait till it's available on the screen.
-  let menu = await toolbox.showFramesMenu({target: btn});
-  await once(menu, "open");
+  let menu = yield toolbox.showFramesMenu({target: btn});
+  yield once(menu, "open");
 
   let frames = menu.items;
   is(frames.length, 2, "We have both frames in the list");
@@ -33,7 +33,7 @@ add_task(async function () {
 
   let navigating = once(target, "will-navigate");
 
-  await navigating;
+  yield navigating;
 
   is($("#reload-notice").hidden, false,
     "The 'reload this page' notice should still be visible when switching to a frame.");
@@ -47,7 +47,7 @@ add_task(async function () {
 
   reload(target);
 
-  await Promise.all([navigating, started]);
+  yield Promise.all([navigating, started]);
 
   is($("#reload-notice").hidden, true,
     "The 'reload this page' notice should be hidden after reloading the frame.");
@@ -56,5 +56,5 @@ add_task(async function () {
   is($("#content").hidden, false,
     "The tool's content should appear after reload.");
 
-  await teardown(target);
+  yield teardown(target);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_webaudio-actor-automation-event.js b/devtools/client/webaudioeditor/test/browser_webaudio-actor-automation-event.js
index b5caa641ebc4..9d542d5f01a6 100644
--- a/devtools/client/webaudioeditor/test/browser_webaudio-actor-automation-event.js
+++ b/devtools/client/webaudioeditor/test/browser_webaudio-actor-automation-event.js
@@ -6,8 +6,8 @@
  * with correct arguments from the content.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(AUTOMATION_URL);
+add_task(function* () {
+  let { target, front } = yield initBackend(AUTOMATION_URL);
   let events = [];
 
   let expected = [
@@ -19,7 +19,7 @@ add_task(async function () {
 
   front.on("automation-event", onAutomationEvent);
 
-  let [_, __, [destNode, oscNode, gainNode], [connect1, connect2]] = await Promise.all([
+  let [_, __, [destNode, oscNode, gainNode], [connect1, connect2]] = yield Promise.all([
     front.setup({ reload: true }),
     once(front, "start-context"),
     get3(front, "create-node"),
@@ -48,5 +48,5 @@ add_task(async function () {
   }
 
   front.off("automation-event", onAutomationEvent);
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_webaudio-actor-connect-param.js b/devtools/client/webaudioeditor/test/browser_webaudio-actor-connect-param.js
index d3abd90ceac5..2910d5bd1606 100644
--- a/devtools/client/webaudioeditor/test/browser_webaudio-actor-connect-param.js
+++ b/devtools/client/webaudioeditor/test/browser_webaudio-actor-connect-param.js
@@ -5,9 +5,9 @@
  * Test the `connect-param` event on the web audio actor.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(CONNECT_PARAM_URL);
-  let [, , [destNode, carrierNode, modNode, gainNode], , connectParam] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(CONNECT_PARAM_URL);
+  let [, , [destNode, carrierNode, modNode, gainNode], , connectParam] = yield Promise.all([
     front.setup({ reload: true }),
     once(front, "start-context"),
     getN(front, "create-node", 4),
@@ -21,5 +21,5 @@ add_task(async function () {
   is(connectParam.dest.actorID, gainNode.actorID, "`connect-param` has correct actor for `dest`");
   is(connectParam.param, "gain", "`connect-param` has correct parameter name for `param`");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/browser_webaudio-actor-destroy-node.js b/devtools/client/webaudioeditor/test/browser_webaudio-actor-destroy-node.js
index 291b50ac9084..e48836c3fa79 100644
--- a/devtools/client/webaudioeditor/test/browser_webaudio-actor-destroy-node.js
+++ b/devtools/client/webaudioeditor/test/browser_webaudio-actor-destroy-node.js
@@ -5,10 +5,10 @@
  * Test `destroy-node` event on WebAudioActor.
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(DESTROY_NODES_URL);
+add_task(function* () {
+  let { target, front } = yield initBackend(DESTROY_NODES_URL);
 
-  let [, , created] = await Promise.all([
+  let [, , created] = yield Promise.all([
     front.setup({ reload: true }),
     once(front, "start-context"),
     // Should create dest, gain, and oscillator node and 10
@@ -21,7 +21,7 @@ add_task(async function () {
   // Force CC so we can ensure it's run to clear out dead AudioNodes
   forceNodeCollection();
 
-  let destroyed = await waitUntilDestroyed;
+  let destroyed = yield waitUntilDestroyed;
 
   destroyed.forEach((node, i) => {
     ok(node.type, "AudioBufferSourceNode", "Only buffer nodes are destroyed");
@@ -29,7 +29,7 @@ add_task(async function () {
       "`destroy-node` called only on AudioNodes in current document.");
   });
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
 
 function actorIsInList(list, actor) {
diff --git a/devtools/client/webaudioeditor/test/browser_webaudio-actor-simple.js b/devtools/client/webaudioeditor/test/browser_webaudio-actor-simple.js
index 764aa3477a81..28ff756512b0 100644
--- a/devtools/client/webaudioeditor/test/browser_webaudio-actor-simple.js
+++ b/devtools/client/webaudioeditor/test/browser_webaudio-actor-simple.js
@@ -5,9 +5,9 @@
  * Test basic communication of Web Audio actor
  */
 
-add_task(async function () {
-  let { target, front } = await initBackend(SIMPLE_CONTEXT_URL);
-  let [_, __, [destNode, oscNode, gainNode], [connect1, connect2]] = await Promise.all([
+add_task(function* () {
+  let { target, front } = yield initBackend(SIMPLE_CONTEXT_URL);
+  let [_, __, [destNode, oscNode, gainNode], [connect1, connect2]] = yield Promise.all([
     front.setup({ reload: true }),
     once(front, "start-context"),
     get3(front, "create-node"),
@@ -26,5 +26,5 @@ add_task(async function () {
   is(source.actorID, gainNode.actorID, "WebAudioActor:connect-node returns correct actor with ID on source (gain->dest)");
   is(dest.actorID, destNode.actorID, "WebAudioActor:connect-node returns correct actor with ID on dest (gain->dest)");
 
-  await removeTab(target.tab);
+  yield removeTab(target.tab);
 });
diff --git a/devtools/client/webaudioeditor/test/head.js b/devtools/client/webaudioeditor/test/head.js
index c0b3a4e431e2..50158b8c81b4 100644
--- a/devtools/client/webaudioeditor/test/head.js
+++ b/devtools/client/webaudioeditor/test/head.js
@@ -62,15 +62,15 @@ function initBackend(aUrl) {
   DebuggerServer.init();
   DebuggerServer.registerAllActors();
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     let front = new WebAudioFront(target.client, target.form);
     return { target, front };
-  })();
+  });
 }
 
 /**
@@ -81,17 +81,17 @@ function initBackend(aUrl) {
 function initWebAudioEditor(aUrl) {
   info("Initializing a web audio editor pane.");
 
-  return (async function () {
-    let tab = await addTab(aUrl);
+  return Task.spawn(function* () {
+    let tab = yield addTab(aUrl);
     let target = TargetFactory.forTab(tab);
 
-    await target.makeRemote();
+    yield target.makeRemote();
 
     Services.prefs.setBoolPref("devtools.webaudioeditor.enabled", true);
-    let toolbox = await gDevTools.showToolbox(target, "webaudioeditor");
+    let toolbox = yield gDevTools.showToolbox(target, "webaudioeditor");
     let panel = toolbox.getCurrentPanel();
     return { target, panel, toolbox };
-  })();
+  });
 }
 
 /**
@@ -325,7 +325,7 @@ function countGraphObjects(win) {
 * Forces cycle collection and GC, used in AudioNode destruction tests.
 */
 function forceNodeCollection() {
-  ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+  ContentTask.spawn(gBrowser.selectedBrowser, {}, function*() {
     // Kill the reference keeping stuff alive.
     content.wrappedJSObject.keepAlive = null;
 
diff --git a/devtools/client/webaudioeditor/views/automation.js b/devtools/client/webaudioeditor/views/automation.js
index 16abf5ca7a23..ad0c37ea96ef 100644
--- a/devtools/client/webaudioeditor/views/automation.js
+++ b/devtools/client/webaudioeditor/views/automation.js
@@ -46,24 +46,24 @@ var AutomationView = {
    * On a new node selection, create the Automation panel for
    * that specific node.
    */
-  async build() {
+  build: Task.async(function* () {
     let node = this._currentNode;
 
-    let props = await node.getParams();
+    let props = yield node.getParams();
     let params = props.filter(({ flags }) => flags && flags.param);
 
     this._createParamButtons(params);
 
     this._selectedParamName = params[0] ? params[0].param : null;
     this.render();
-  },
+  }),
 
   /**
    * Renders the graph for specified `paramName`. Called when
    * the parameter view is changed, or when new param data events
    * are fired for the currently specified param.
    */
-  async render() {
+  render: Task.async(function* () {
     let node = this._currentNode;
     let paramName = this._selectedParamName;
     // Escape if either node or parameter name does not exist.
@@ -73,11 +73,11 @@ var AutomationView = {
       return;
     }
 
-    let { values, events } = await node.getAutomationData(paramName);
+    let { values, events } = yield node.getAutomationData(paramName);
     this._setState(events.length ? "show" : "no-events");
-    await this.graph.setDataWhenReady(values);
+    yield this.graph.setDataWhenReady(values);
     window.emit(EVENTS.UI_AUTOMATION_TAB_RENDERED, node.id);
-  },
+  }),
 
   /**
    * Create the buttons for each AudioParam, that when clicked,
diff --git a/devtools/client/webaudioeditor/views/inspector.js b/devtools/client/webaudioeditor/views/inspector.js
index d0f2471df828..2ea57a40d876 100644
--- a/devtools/client/webaudioeditor/views/inspector.js
+++ b/devtools/client/webaudioeditor/views/inspector.js
@@ -76,7 +76,7 @@ var InspectorView = {
    * Takes a AudioNodeView `node` and sets it as the current
    * node and scaffolds the inspector view based off of the new node.
    */
-  async setCurrentAudioNode(node) {
+  setCurrentAudioNode: Task.async(function* (node) {
     this._currentNode = node || null;
 
     // If no node selected, set the inspector back to "no AudioNode selected"
@@ -93,7 +93,7 @@ var InspectorView = {
       this._buildToolbar();
       window.emit(EVENTS.UI_INSPECTOR_NODE_SET, this._currentNode.id);
     }
-  },
+  }),
 
   /**
    * Returns the current AudioNodeView.
diff --git a/devtools/client/webaudioeditor/views/properties.js b/devtools/client/webaudioeditor/views/properties.js
index b80db1bd23d2..daef2802519d 100644
--- a/devtools/client/webaudioeditor/views/properties.js
+++ b/devtools/client/webaudioeditor/views/properties.js
@@ -63,13 +63,13 @@ var PropertiesView = {
    * Reconstructs the `Properties` tab in the inspector
    * with the `this._currentNode` as it's source.
    */
-  async _buildPropertiesView() {
+  _buildPropertiesView: Task.async(function* () {
     let propsView = this._propsView;
     let node = this._currentNode;
     propsView.empty();
 
     let audioParamsScope = propsView.addScope("AudioParams");
-    let props = await node.getParams();
+    let props = yield node.getParams();
 
     // Disable AudioParams VariableView expansion
     // when there are no props i.e. AudioDestinationNode
@@ -89,7 +89,7 @@ var PropertiesView = {
     audioParamsScope.expanded = true;
 
     window.emit(EVENTS.UI_PROPERTIES_TAB_RENDERED, node.id);
-  },
+  }),
 
   /**
    * Toggles the display of the "empty" properties view when
@@ -126,7 +126,7 @@ var PropertiesView = {
   /**
    * Executed when an audio prop is changed in the UI.
    */
-  async _onEval(variable, value) {
+  _onEval: Task.async(function* (variable, value) {
     let ownerScope = variable.ownerView;
     let node = this._currentNode;
     let propName = variable.name;
@@ -143,7 +143,7 @@ var PropertiesView = {
         } else {
           value = JSON.parse(value);
         }
-        error = await node.actor.setParam(propName, value);
+        error = yield node.actor.setParam(propName, value);
       }
       catch (e) {
         error = e;
@@ -159,5 +159,5 @@ var PropertiesView = {
     } else {
       window.emit(EVENTS.UI_SET_PARAM_ERROR, node.id, propName, value);
     }
-  }
+  })
 };
diff --git a/devtools/client/webconsole/console-output.js b/devtools/client/webconsole/console-output.js
index 173381340d2e..98fa15cb2858 100644
--- a/devtools/client/webconsole/console-output.js
+++ b/devtools/client/webconsole/console-output.js
@@ -19,6 +19,7 @@ const XHTML_NS = "http://www.w3.org/1999/xhtml";
 
 const WebConsoleUtils = require("devtools/client/webconsole/utils").Utils;
 const { getSourceNames } = require("devtools/client/shared/source-utils");
+const {Task} = require("devtools/shared/task");
 const l10n = require("devtools/client/webconsole/webconsole-l10n");
 const nodeConstants = require("devtools/shared/dom-node-constants");
 const {PluralForm} = require("devtools/shared/plural-form");
@@ -3084,7 +3085,7 @@ Widgets.ObjectRenderers.add({
    * if the node is in a DocumentFragment or not part of the tree, or not of
    * type nodeConstants.ELEMENT_NODE).
    */
-  async linkToInspector() {
+  linkToInspector: Task.async(function* () {
     if (this._linkedToInspector) {
       return;
     }
@@ -3104,8 +3105,8 @@ Widgets.ObjectRenderers.add({
     }
 
     // Checking that the inspector supports the node
-    await this.toolbox.initInspector();
-    this._nodeFront = await this.toolbox.walker.getNodeActorFromObjectActor(
+    yield this.toolbox.initInspector();
+    this._nodeFront = yield this.toolbox.walker.getNodeActorFromObjectActor(
       this.objectActor.actor);
     if (!this._nodeFront) {
       throw new Error("The object cannot be linked to the inspector, the " +
@@ -3134,22 +3135,22 @@ Widgets.ObjectRenderers.add({
       onClick: this.openNodeInInspector.bind(this)
     });
     this._openInspectorNode.title = l10n.getStr("openNodeInInspector");
-  },
+  }),
 
   /**
    * Highlight the DOMNode corresponding to the ObjectActor in the page.
    * @return a promise that resolves when the node has been highlighted, or
    * rejects if the node cannot be highlighted (detached from the DOM)
    */
-  async highlightDomNode() {
-    await this.linkToInspector();
-    let isAttached = await this.toolbox.walker.isInDOMTree(this._nodeFront);
+  highlightDomNode: Task.async(function* () {
+    yield this.linkToInspector();
+    let isAttached = yield this.toolbox.walker.isInDOMTree(this._nodeFront);
     if (isAttached) {
-      await this.toolbox.highlighterUtils.highlightNodeFront(this._nodeFront);
+      yield this.toolbox.highlighterUtils.highlightNodeFront(this._nodeFront);
     } else {
       throw new Error("Node is not attached.");
     }
-  },
+  }),
 
   /**
    * Unhighlight a previously highlit node
@@ -3169,20 +3170,20 @@ Widgets.ObjectRenderers.add({
    * (detached from the DOM). Note that in any case, the inspector panel will
    * be switched to.
    */
-  async openNodeInInspector() {
-    await this.linkToInspector();
-    await this.toolbox.selectTool("inspector");
+  openNodeInInspector: Task.async(function* () {
+    yield this.linkToInspector();
+    yield this.toolbox.selectTool("inspector");
 
-    let isAttached = await this.toolbox.walker.isInDOMTree(this._nodeFront);
+    let isAttached = yield this.toolbox.walker.isInDOMTree(this._nodeFront);
     if (isAttached) {
       let onReady = defer();
       this.toolbox.inspector.once("inspector-updated", onReady.resolve);
-      await this.toolbox.selection.setNodeFront(this._nodeFront, "console");
-      await onReady.promise;
+      yield this.toolbox.selection.setNodeFront(this._nodeFront, "console");
+      yield onReady.promise;
     } else {
       throw new Error("Node is not attached.");
     }
-  },
+  }),
 
   destroy: function () {
     if (this.toolbox && this._nodeFront) {
diff --git a/devtools/client/webconsole/net/test/mochitest/browser_net_basic.js b/devtools/client/webconsole/net/test/mochitest/browser_net_basic.js
index ab29b8e7b1f1..57273bec0607 100644
--- a/devtools/client/webconsole/net/test/mochitest/browser_net_basic.js
+++ b/devtools/client/webconsole/net/test/mochitest/browser_net_basic.js
@@ -13,12 +13,12 @@ const JSON_XHR_URL = URL_ROOT + "test.json";
  * checks the related log in the Console panel can
  * be expanded.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy basic started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: JSON_XHR_URL
   });
diff --git a/devtools/client/webconsole/net/test/mochitest/browser_net_cookies.js b/devtools/client/webconsole/net/test/mochitest/browser_net_cookies.js
index b2d0f37e4b7a..cfd85c2edb53 100644
--- a/devtools/client/webconsole/net/test/mochitest/browser_net_cookies.js
+++ b/devtools/client/webconsole/net/test/mochitest/browser_net_cookies.js
@@ -13,18 +13,18 @@ const JSON_XHR_URL = URL_ROOT + "test-cookies.json";
  * networks details in the Console panel and checks that
  * Cookies are properly displayed.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy cookies started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: JSON_XHR_URL
   });
 
   // Select "Cookies" tab
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "cookies");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "cookies");
 
   let requestCookieName = tabBody.querySelector(
     ".netInfoGroup.requestCookies .netInfoParamName > span[title='bar']");
diff --git a/devtools/client/webconsole/net/test/mochitest/browser_net_headers.js b/devtools/client/webconsole/net/test/mochitest/browser_net_headers.js
index a2b1a709685a..134caf4fff60 100644
--- a/devtools/client/webconsole/net/test/mochitest/browser_net_headers.js
+++ b/devtools/client/webconsole/net/test/mochitest/browser_net_headers.js
@@ -13,21 +13,21 @@ const JSON_XHR_URL = URL_ROOT + "test.json";
  * networks details in the Console panel and checks that
  * HTTP headers are there.
  */
-add_task(async function () {
+add_task(function* () {
   // Disable rcwn to make cache behavior deterministic.
-  await pushPref("network.http.rcwn.enabled", false);
+  yield pushPref("network.http.rcwn.enabled", false);
 
   info("Test XHR Spy headers started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: JSON_XHR_URL
   });
 
   // Select "Headers" tab
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "headers");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "headers");
   let paramName = tabBody.querySelector(
     ".netInfoParamName > span[title='content-type']");
 
diff --git a/devtools/client/webconsole/net/test/mochitest/browser_net_params.js b/devtools/client/webconsole/net/test/mochitest/browser_net_params.js
index 0ef0f250fe1d..d8b0e2c84bf1 100644
--- a/devtools/client/webconsole/net/test/mochitest/browser_net_params.js
+++ b/devtools/client/webconsole/net/test/mochitest/browser_net_params.js
@@ -13,19 +13,19 @@ const JSON_XHR_URL = URL_ROOT + "test.json";
  * networks details in the Console panel and checks that
  * HTTP parameters (query string) are there.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy params started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: JSON_XHR_URL,
     queryString: "?foo=bar"
   });
 
   // Check headers
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "params");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "params");
 
   let paramName = tabBody.querySelector(
     ".netInfoParamName > span[title='foo']");
@@ -44,19 +44,19 @@ add_task(async function () {
 /**
  * Test URL parameters with the same name.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy params started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: JSON_XHR_URL,
     queryString: "?box[]=123&box[]=456"
   });
 
   // Check headers
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "params");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "params");
 
   let params = tabBody.querySelectorAll(
     ".netInfoParamName > span[title='box[]']");
diff --git a/devtools/client/webconsole/net/test/mochitest/browser_net_post.js b/devtools/client/webconsole/net/test/mochitest/browser_net_post.js
index 98bccf7130a5..f6e776ef0fd7 100644
--- a/devtools/client/webconsole/net/test/mochitest/browser_net_post.js
+++ b/devtools/client/webconsole/net/test/mochitest/browser_net_post.js
@@ -18,31 +18,31 @@ const xmlPostBody = "<xml><name>John</name></xml>";
  * networks details in the Console panel and checks that
  * Post data are properly rendered.
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy post plain body started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "POST",
     url: JSON_XHR_URL,
     body: plainPostBody
   });
 
   // Check post body data
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "post");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "post");
   let postContent = tabBody.querySelector(
     ".netInfoGroup.raw.opened .netInfoGroupContent");
   is(postContent.textContent, plainPostBody,
     "Post body must be properly rendered");
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy post JSON body started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "POST",
     url: JSON_XHR_URL,
     body: jsonData,
@@ -53,7 +53,7 @@ add_task(async function () {
   });
 
   // Check post body data
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "post");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "post");
   let postContent = tabBody.querySelector(
     ".netInfoGroup.json.opened .netInfoGroupContent");
   is(postContent.textContent, jsonRendered,
@@ -64,12 +64,12 @@ add_task(async function () {
   ok(!rawPostContent, "Raw response group must be collapsed");
 });
 
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy post XML body started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "POST",
     url: JSON_XHR_URL,
     body: xmlPostBody,
@@ -80,7 +80,7 @@ add_task(async function () {
   });
 
   // Check post body data
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "post");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "post");
   let rawPostContent = tabBody.querySelector(
     ".netInfoGroup.raw.opened .netInfoGroupContent");
   is(rawPostContent.textContent, xmlPostBody,
diff --git a/devtools/client/webconsole/net/test/mochitest/browser_net_response.js b/devtools/client/webconsole/net/test/mochitest/browser_net_response.js
index 9e4a3ad8ff02..ec5543043ea7 100644
--- a/devtools/client/webconsole/net/test/mochitest/browser_net_response.js
+++ b/devtools/client/webconsole/net/test/mochitest/browser_net_response.js
@@ -20,18 +20,18 @@ const jsonResponseBody = "name\"John\"";
 /**
  * Validate plain text response
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy respone plain body started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: TEXT_XHR_URL,
   });
 
   // Check response body data
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "response");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "response");
   let responseContent = tabBody.querySelector(
     ".netInfoGroup.raw.opened .netInfoGroupContent");
 
@@ -42,18 +42,18 @@ add_task(async function () {
 /**
  * Validate XML response
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy response XML body started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: XML_XHR_URL,
   });
 
   // Check response body data
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "response");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "response");
   let rawResponseContent = tabBody.querySelector(
     ".netInfoGroup.raw.opened .netInfoGroupContent");
   ok(rawResponseContent, "Raw response group must not be collapsed");
@@ -62,18 +62,18 @@ add_task(async function () {
 /**
  * Validate JSON response
  */
-add_task(async function () {
+add_task(function* () {
   info("Test XHR Spy response JSON body started");
 
-  let {hud} = await addTestTab(TEST_PAGE_URL);
+  let {hud} = yield addTestTab(TEST_PAGE_URL);
 
-  let netInfoBody = await executeAndInspectXhr(hud, {
+  let netInfoBody = yield executeAndInspectXhr(hud, {
     method: "GET",
     url: JSON_XHR_URL,
   });
 
   // Check response body data
-  let tabBody = await selectNetInfoTab(hud, netInfoBody, "response");
+  let tabBody = yield selectNetInfoTab(hud, netInfoBody, "response");
   let responseContent = tabBody.querySelector(
     ".netInfoGroup.json .netInfoGroupContent");
 
diff --git a/devtools/client/webconsole/net/test/mochitest/head.js b/devtools/client/webconsole/net/test/mochitest/head.js
index 6f1e5ecc2c84..dd69370fa39c 100644
--- a/devtools/client/webconsole/net/test/mochitest/head.js
+++ b/devtools/client/webconsole/net/test/mochitest/head.js
@@ -25,7 +25,7 @@ registerCleanupFunction(() => {
 // Use the old webconsole since the new one doesn't yet support
 // XHR spy. See Bug 1304794.
 Services.prefs.setBoolPref("devtools.webconsole.new-frontend-enabled", false);
-registerCleanupFunction(function() {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.webconsole.new-frontend-enabled");
 });
 
@@ -37,21 +37,21 @@ registerCleanupFunction(function() {
 function addTestTab(url) {
   info("Adding a new JSON tab with URL: '" + url + "'");
 
-  return (async function () {
-    let tab = await addTab(url);
+  return Task.spawn(function* () {
+    let tab = yield addTab(url);
 
     // Load devtools/shared/test/frame-script-utils.js
     loadFrameScriptUtils(tab.linkedBrowser);
 
     // Open the Console panel
-    let hud = await openConsole();
+    let hud = yield openConsole();
 
     return {
       tab: tab,
       browser: tab.linkedBrowser,
       hud: hud
     };
-  })();
+  });
 }
 
 /**
@@ -73,9 +73,9 @@ function executeAndInspectXhr(hud, options) {
     requestHeaders: options.requestHeaders
   });
 
-  return (async function () {
+  return Task.spawn(function* () {
     // Wait till the appropriate Net log appears in the Console panel.
-    let rules = await waitForMessages({
+    let rules = yield waitForMessages({
       webconsole: hud,
       messages: [{
         text: options.url,
@@ -92,12 +92,12 @@ function executeAndInspectXhr(hud, options) {
     // Open XHR HTTP details body and wait till the UI fetches
     // all necessary data from the backend. All RPD requests
     // needs to be finished before we can continue testing.
-    await synthesizeMouseClickSoon(hud, body);
-    await waitForBackend(msg);
+    yield synthesizeMouseClickSoon(hud, body);
+    yield waitForBackend(msg);
     let netInfoBody = body.querySelector(".netInfoBody");
     ok(netInfoBody, "Net info body must exist");
     return netInfoBody;
-  })();
+  });
 }
 
 /**
@@ -128,14 +128,14 @@ function selectNetInfoTab(hud, netInfoBody, tabId) {
   // UI is populated with data from the backend.
   // There must be no pending RDP requests before we can
   // continue testing the UI.
-  return (async function () {
-    await synthesizeMouseClickSoon(hud, tab);
+  return Task.spawn(function* () {
+    yield synthesizeMouseClickSoon(hud, tab);
     let msg = getAncestorByClass(netInfoBody, "message");
-    await waitForBackend(msg);
+    yield waitForBackend(msg);
     let tabBody = netInfoBody.querySelector("." + tabId + "TabBox");
     ok(tabBody, "Tab body must exist");
     return tabBody;
-  })();
+  });
 }
 
 /**
diff --git a/devtools/client/webconsole/new-console-output/test/chrome/head.js b/devtools/client/webconsole/new-console-output/test/chrome/head.js
index a4464999400d..bb201e904653 100644
--- a/devtools/client/webconsole/new-console-output/test/chrome/head.js
+++ b/devtools/client/webconsole/new-console-output/test/chrome/head.js
@@ -4,7 +4,9 @@
 
 "use strict";
 
+var { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm", {});
 var { BrowserLoader } = ChromeUtils.import("resource://devtools/client/shared/browser-loader.js", {});
+var { Task } = require("devtools/shared/task");
 
 var { require: browserRequire } = BrowserLoader({
   baseURI: "resource://devtools/client/webconsole/",
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_console_api.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_console_api.js
index a97b4dc3d2b0..c85b4b8ae705 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_console_api.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_console_api.js
@@ -7,11 +7,11 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let generatedStubs = await generateConsoleApiStubs();
+add_task(function* () {
+  let generatedStubs = yield generateConsoleApiStubs();
 
   let repoStubFilePath = getTestFilePath("../stubs/consoleApi.js");
-  let repoStubFileContent = await OS.File.read(repoStubFilePath, { encoding: "utf-8" });
+  let repoStubFileContent = yield OS.File.read(repoStubFilePath, { encoding: "utf-8" });
 
   if (generatedStubs != repoStubFileContent) {
     ok(false, "The consoleApi stubs file needs to be updated by running " +
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_css_message.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_css_message.js
index 2b4ef9eb26d5..772e13058612 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_css_message.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_css_message.js
@@ -7,11 +7,11 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let generatedStubs = await generateCssMessageStubs();
+add_task(function* () {
+  let generatedStubs = yield generateCssMessageStubs();
 
   let repoStubFilePath = getTestFilePath("../stubs/cssMessage.js");
-  let repoStubFileContent = await OS.File.read(repoStubFilePath, { encoding: "utf-8" });
+  let repoStubFileContent = yield OS.File.read(repoStubFilePath, { encoding: "utf-8" });
 
   if (generatedStubs != repoStubFileContent) {
     ok(false, "The cssMessage stubs file needs to be updated by running " +
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_evaluation_result.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_evaluation_result.js
index 788dd5c68cd7..90b11405ca2d 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_evaluation_result.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_evaluation_result.js
@@ -7,11 +7,11 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let generatedStubs = await generateEvaluationResultStubs();
+add_task(function* () {
+  let generatedStubs = yield generateEvaluationResultStubs();
 
   let repoStubFilePath = getTestFilePath("../stubs/evaluationResult.js");
-  let repoStubFileContent = await OS.File.read(repoStubFilePath, { encoding: "utf-8" });
+  let repoStubFileContent = yield OS.File.read(repoStubFilePath, { encoding: "utf-8" });
 
   if (generatedStubs != repoStubFileContent) {
     ok(false, "The evaluationResult stubs file needs to be updated by running " +
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_network_event.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_network_event.js
index 52a3d0e9814f..8587a832eed3 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_network_event.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_network_event.js
@@ -7,11 +7,11 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let generatedStubs = await generateNetworkEventStubs();
+add_task(function* () {
+  let generatedStubs = yield generateNetworkEventStubs();
 
   let repoStubFilePath = getTestFilePath("../stubs/networkEvent.js");
-  let repoStubFileContent = await OS.File.read(repoStubFilePath, { encoding: "utf-8" });
+  let repoStubFileContent = yield OS.File.read(repoStubFilePath, { encoding: "utf-8" });
 
   is(generatedStubs, repoStubFileContent, "Generated stub has the expected content");
   if (generatedStubs != repoStubFileContent) {
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_page_error.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_page_error.js
index 105e23daa681..2604675da476 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_page_error.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_check_stubs_page_error.js
@@ -7,11 +7,11 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let generatedStubs = await generatePageErrorStubs();
+add_task(function* () {
+  let generatedStubs = yield generatePageErrorStubs();
 
   let repoStubFilePath = getTestFilePath("../stubs/pageError.js");
-  let repoStubFileContent = await OS.File.read(repoStubFilePath, { encoding: "utf-8" });
+  let repoStubFileContent = yield OS.File.read(repoStubFilePath, { encoding: "utf-8" });
 
   if (generatedStubs != repoStubFileContent) {
     ok(false, "The pageError stubs file needs to be updated by running " +
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_console_api.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_console_api.js
index 4d5bc4ede0bc..281018e15e2a 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_console_api.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_console_api.js
@@ -7,9 +7,9 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let fileContent = await generateConsoleApiStubs();
+add_task(function* () {
+  let fileContent = yield generateConsoleApiStubs();
   let filePath = OS.Path.join(`${BASE_PATH}/stubs`, "consoleApi.js");
-  await OS.File.writeAtomic(filePath, fileContent);
+  yield OS.File.writeAtomic(filePath, fileContent);
   ok(true, "Make the test not fail");
 });
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_css_message.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_css_message.js
index b81fbcf5187c..bbd9118a1e1a 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_css_message.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_css_message.js
@@ -5,9 +5,9 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let fileContent = await generateCssMessageStubs();
+add_task(function* () {
+  let fileContent = yield generateCssMessageStubs();
   let filePath = OS.Path.join(`${BASE_PATH}/stubs`, "cssMessage.js");
-  await OS.File.writeAtomic(filePath, fileContent);
+  yield OS.File.writeAtomic(filePath, fileContent);
   ok(true, "Make the test not fail");
 });
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_evaluation_result.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_evaluation_result.js
index 62f1c2dadd47..ee5a809bc539 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_evaluation_result.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_evaluation_result.js
@@ -7,9 +7,9 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let fileContent = await generateEvaluationResultStubs();
+add_task(function* () {
+  let fileContent = yield generateEvaluationResultStubs();
   let filePath = OS.Path.join(`${BASE_PATH}/stubs`, "evaluationResult.js");
-  await OS.File.writeAtomic(filePath, fileContent);
+  yield OS.File.writeAtomic(filePath, fileContent);
   ok(true, "Make the test not fail");
 });
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_network_event.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_network_event.js
index 7b2d49377b3e..43ac579a40fd 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_network_event.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_network_event.js
@@ -7,9 +7,9 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let fileContent = await generateNetworkEventStubs();
+add_task(function* () {
+  let fileContent = yield generateNetworkEventStubs();
   let filePath = OS.Path.join(`${BASE_PATH}/stubs/networkEvent.js`);
-  await OS.File.writeAtomic(filePath, fileContent);
+  yield OS.File.writeAtomic(filePath, fileContent);
   ok(true, "Make the test not fail");
 });
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_page_error.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_page_error.js
index 6e8afb3927fc..9ddef257225e 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_page_error.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/browser_webconsole_update_stubs_page_error.js
@@ -7,9 +7,9 @@
 
 ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-add_task(async function () {
-  let fileContent = await generatePageErrorStubs();
+add_task(function* () {
+  let fileContent = yield generatePageErrorStubs();
   let filePath = OS.Path.join(`${BASE_PATH}/stubs`, "pageError.js");
-  await OS.File.writeAtomic(filePath, fileContent);
+  yield OS.File.writeAtomic(filePath, fileContent);
   ok(true, "Make the test not fail");
 });
diff --git a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/head.js b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/head.js
index af843559bada..3a75874285cf 100644
--- a/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/head.js
+++ b/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/head.js
@@ -293,7 +293,7 @@ module.exports = {
 `;
 }
 
-async function generateConsoleApiStubs() {
+function* generateConsoleApiStubs() {
   const TEST_URI = "http://example.com/browser/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/test-console-api.html";
 
   // Hiding log messages so we don't get unwanted client/server communication.
@@ -304,7 +304,7 @@ async function generateConsoleApiStubs() {
     packets: [],
   };
 
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
   const hud = toolbox.getCurrentPanel().hud;
   let {ui} = hud;
   ok(ui.jsterm, "jsterm exists");
@@ -325,7 +325,7 @@ async function generateConsoleApiStubs() {
       toolbox.target.client.addListener("consoleAPICall", listener);
     });
 
-    await ContentTask.spawn(
+    yield ContentTask.spawn(
       gBrowser.selectedBrowser,
       [key, code],
       function ([subKey, subCode]) {
@@ -338,16 +338,16 @@ async function generateConsoleApiStubs() {
       }
     );
 
-    await received;
+    yield received;
   }
 
   Services.prefs.clearUserPref(PREFS.FILTER.LOG);
 
-  await closeTabAndToolbox();
+  yield closeTabAndToolbox();
   return formatFile(stubs, "ConsoleMessage");
 }
 
-async function generateCssMessageStubs() {
+function* generateCssMessageStubs() {
   const TEST_URI = "http://example.com/browser/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/test-css-message.html";
 
   let stubs = {
@@ -355,7 +355,7 @@ async function generateCssMessageStubs() {
     packets: [],
   };
 
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
 
   for (let [key, code] of cssMessage) {
     let received = new Promise(resolve => {
@@ -371,7 +371,7 @@ async function generateCssMessageStubs() {
       });
     });
 
-    await ContentTask.spawn(
+    yield ContentTask.spawn(
       gBrowser.selectedBrowser,
       [key, code],
       function ([subKey, subCode]) {
@@ -382,14 +382,14 @@ async function generateCssMessageStubs() {
       }
     );
 
-    await received;
+    yield received;
   }
 
-  await closeTabAndToolbox();
+  yield closeTabAndToolbox();
   return formatFile(stubs, "ConsoleMessage");
 }
 
-async function generateEvaluationResultStubs() {
+function* generateEvaluationResultStubs() {
   const TEST_URI = "data:text/html;charset=utf-8,stub generation";
 
   let stubs = {
@@ -397,21 +397,21 @@ async function generateEvaluationResultStubs() {
     packets: [],
   };
 
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
 
   for (let [key, code] of evaluationResult) {
-    const packet = await new Promise(resolve => {
+    const packet = yield new Promise(resolve => {
       toolbox.target.activeConsole.evaluateJS(code, resolve);
     });
     stubs.packets.push(formatPacket(key, packet));
     stubs.preparedMessages.push(formatStub(key, packet));
   }
 
-  await closeTabAndToolbox();
+  yield closeTabAndToolbox();
   return formatFile(stubs, "ConsoleMessage");
 }
 
-async function generateNetworkEventStubs() {
+function* generateNetworkEventStubs() {
   const TEST_URI = "http://example.com/browser/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/test-network-event.html";
 
   let stubs = {
@@ -419,7 +419,7 @@ async function generateNetworkEventStubs() {
     packets: [],
   };
 
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
   let {ui} = toolbox.getCurrentPanel().hud;
 
   for (let [key, {keys, code}] of networkEvent) {
@@ -461,7 +461,7 @@ async function generateNetworkEventStubs() {
       });
     });
 
-    await ContentTask.spawn(
+    yield ContentTask.spawn(
       gBrowser.selectedBrowser,
       [key, code],
       function ([subKey, subCode]) {
@@ -474,14 +474,14 @@ async function generateNetworkEventStubs() {
       }
     );
 
-    await Promise.all([onNetwork, onNetworkUpdate]);
+    yield Promise.all([onNetwork, onNetworkUpdate]);
   }
 
-  await closeTabAndToolbox();
+  yield closeTabAndToolbox();
   return formatFile(stubs, "NetworkEventMessage");
 }
 
-async function generatePageErrorStubs() {
+function* generatePageErrorStubs() {
   const TEST_URI = "http://example.com/browser/devtools/client/webconsole/new-console-output/test/fixtures/stub-generators/test-console-api.html";
 
   let stubs = {
@@ -489,7 +489,7 @@ async function generatePageErrorStubs() {
     packets: [],
   };
 
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
 
   for (let [key, code] of pageError) {
     let received = new Promise(resolve => {
@@ -508,7 +508,7 @@ async function generatePageErrorStubs() {
       expectUncaughtException();
     }
 
-    await ContentTask.spawn(
+    yield ContentTask.spawn(
       gBrowser.selectedBrowser,
       [key, code],
       function ([subKey, subCode]) {
@@ -520,9 +520,9 @@ async function generatePageErrorStubs() {
       }
     );
 
-    await received;
+    yield received;
   }
 
-  await closeTabAndToolbox();
+  yield closeTabAndToolbox();
   return formatFile(stubs, "ConsoleMessage");
 }
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_clear_method.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_clear_method.js
index 940b5d94db5d..d4e01b445d27 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_clear_method.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_clear_method.js
@@ -11,21 +11,21 @@
 
 const TEST_URI = "data:text/html;charset=utf8,<p>Bug 1296870";
 
-add_task(async function () {
-  await loadTab(TEST_URI);
-  let hud = await HUDService.toggleBrowserConsole();
+add_task(function* () {
+  yield loadTab(TEST_URI);
+  let hud = yield HUDService.toggleBrowserConsole();
 
   info("Log a new message from the content page");
-  ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+  ContentTask.spawn(gBrowser.selectedBrowser, {}, function* () {
     content.wrappedJSObject.console.log("msg");
   });
-  await waitForMessage("msg", hud);
+  yield waitForMessage("msg", hud);
 
   info("Send a console.clear() from the content page");
-  ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+  ContentTask.spawn(gBrowser.selectedBrowser, {}, function* () {
     content.wrappedJSObject.console.clear();
   });
-  await waitForMessage("Console was cleared", hud);
+  yield waitForMessage("Console was cleared", hud);
 
   info("Check that the messages logged after the first clear are still displayed");
   isnot(hud.outputNode.textContent.indexOf("msg"), -1, "msg is in the output");
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_webconsole_private_browsing.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_webconsole_private_browsing.js
index 8d99e3611325..48e2514d2518 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_webconsole_private_browsing.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_console_webconsole_private_browsing.js
@@ -41,7 +41,7 @@ function test() {
     ConsoleAPIStorage.clearEvents();
 
     // Add a non-private message to the browser console.
-    ContentTask.spawn(gBrowser.selectedBrowser, null, async function () {
+    ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
       content.console.log("bug874061-not-private");
     });
 
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_closure_inspection.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_closure_inspection.js
index bbc8cc21d75b..db25b2ebbc17 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_closure_inspection.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_closure_inspection.js
@@ -17,7 +17,7 @@ var gWebConsole, gJSTerm, gVariablesView;
 
 // Force the old debugger UI since it's directly used (see Bug 1301705)
 Services.prefs.setBoolPref("devtools.debugger.new-debugger-frontend", false);
-registerCleanupFunction(function () {
+registerCleanupFunction(function* () {
   Services.prefs.clearUserPref("devtools.debugger.new-debugger-frontend");
 });
 
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_console_table.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_console_table.js
index ed628f7c8119..cd72ae774425 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_console_table.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_console_table.js
@@ -11,8 +11,8 @@
 const TEST_URI = "http://example.com/browser/devtools/client/webconsole/" +
                  "new-console-output/test/mochitest/test-console-table.html";
 
-add_task(async function () {
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+add_task(function* () {
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
   let hud = toolbox.getCurrentPanel().hud;
 
   function Person(firstName, lastName) {
@@ -131,14 +131,14 @@ add_task(async function () {
     }
   }];
 
-  await ContentTask.spawn(gBrowser.selectedBrowser, testCases, function (tests) {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, testCases, function (tests) {
     tests.forEach((test) => {
       content.wrappedJSObject.doConsoleTable(test.input, test.headers);
     });
   });
   let nodes = [];
   for (let testCase of testCases) {
-    let node = await waitFor(
+    let node = yield waitFor(
       () => findConsoleTable(hud.ui.outputNode, testCases.indexOf(testCase))
     );
     nodes.push(node);
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_file_uri.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_file_uri.js
index 47e716581e30..285aac64c780 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_file_uri.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_file_uri.js
@@ -12,7 +12,7 @@ const TEST_FILE = "test-network.html";
 
 var hud;
 
-add_task(async function () {
+add_task(function* () {
   Services.prefs.setBoolPref(PREF, true);
 
   let jar = getJar(getRootDirectory(gTestPath));
@@ -27,16 +27,16 @@ add_task(async function () {
   // the file:// URI, otherwise we won't get the same web console.
   let remoteType = E10SUtils.getRemoteTypeForURI(uri.spec,
                                                  gMultiProcessBrowser);
-  let { browser } = await loadTab("about:blank", remoteType);
+  let { browser } = yield loadTab("about:blank", remoteType);
 
-  hud = await openConsole();
+  hud = yield openConsole();
   hud.jsterm.clearOutput();
 
   let loaded = loadBrowser(browser);
   BrowserTestUtils.loadURI(gBrowser.selectedBrowser, uri.spec);
-  await loaded;
+  yield loaded;
 
-  await testMessages();
+  yield testMessages();
 
   Services.prefs.clearUserPref(PREF);
   hud = null;
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_init.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_init.js
index e8a514a862b3..10bc004a7689 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_init.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_init.js
@@ -8,8 +8,8 @@
 const TEST_URI = "http://example.com/browser/devtools/client/webconsole/" +
                  "new-console-output/test/mochitest/test-console.html";
 
-add_task(async function () {
-  let toolbox = await openNewTabAndToolbox(TEST_URI, "webconsole");
+add_task(function* () {
+  let toolbox = yield openNewTabAndToolbox(TEST_URI, "webconsole");
   let hud = toolbox.getCurrentPanel().hud;
   let {ui} = hud;
 
@@ -23,11 +23,11 @@ add_task(async function () {
     ]
   });
 
-  await ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
+  yield ContentTask.spawn(gBrowser.selectedBrowser, {}, function () {
     content.wrappedJSObject.doLogs(20);
   });
 
-  await receievedMessages;
+  yield receievedMessages;
 
   const outputContainer = ui.outputNode.querySelector(".webconsole-output");
   is(outputContainer.querySelectorAll(".message.console-api").length, 20,
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_input_field_focus_on_panel_select.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_input_field_focus_on_panel_select.js
index d87937f5e759..293e1fba2bd5 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_input_field_focus_on_panel_select.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_input_field_focus_on_panel_select.js
@@ -12,9 +12,9 @@
 
 const TEST_URI = "data:text/html;charset=utf8,<p>hello";
 
-add_task(async function () {
-  await loadTab(TEST_URI);
-  let hud = await openConsole();
+add_task(function* () {
+  yield loadTab(TEST_URI);
+  let hud = yield openConsole();
   hud.jsterm.clearOutput();
 
   is(hud.jsterm.inputNode.hasAttribute("focused"), true,
@@ -28,8 +28,8 @@ add_task(async function () {
   is(hud.jsterm.inputNode.hasAttribute("focused"), false,
      "inputNode shouldn't be focused");
 
-  await openInspector();
-  hud = await openConsole();
+  yield openInspector();
+  hud = yield openConsole();
 
   is(hud.jsterm.inputNode.hasAttribute("focused"), true,
      "inputNode should be focused");
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_location_scratchpad_link.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_location_scratchpad_link.js
index 57495a2cf96c..ff0bc4c8b6fd 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_location_scratchpad_link.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_location_scratchpad_link.js
@@ -7,14 +7,14 @@
 
 const TEST_URI = "data:text/html;charset=utf8,<p>test Scratchpad panel linking</p>";
 
-add_task(async function () {
-  await pushPref("devtools.scratchpad.enabled", true);
-  await openNewTabAndToolbox(TEST_URI);
+add_task(function* () {
+  yield pushPref("devtools.scratchpad.enabled", true);
+  yield openNewTabAndToolbox(TEST_URI);
 
   info("Opening toolbox with Scratchpad panel");
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "scratchpad", "window");
+  let toolbox = yield gDevTools.showToolbox(target, "scratchpad", "window");
 
   let scratchpadPanel = toolbox.getPanel("scratchpad");
   let { scratchpad } = scratchpadPanel;
@@ -23,7 +23,7 @@ add_task(async function () {
 
   info("Switching to webconsole panel");
 
-  let webconsolePanel = await toolbox.selectTool("webconsole");
+  let webconsolePanel = yield toolbox.selectTool("webconsole");
   let { hud } = webconsolePanel;
   is(toolbox.getCurrentPanel(), webconsolePanel,
     "Webconsole is currently selected panel");
@@ -33,7 +33,7 @@ add_task(async function () {
   let messageText = "foobar-from-scratchpad";
   scratchpad.setText(`console.log('${messageText}')`);
   scratchpad.run();
-  let message = await waitFor(() => findMessage(hud, messageText));
+  let message = yield waitFor(() => findMessage(hud, messageText));
 
   info("Clicking link to switch to and focus Scratchpad");
 
@@ -45,7 +45,7 @@ add_task(async function () {
   });
 
   EventUtils.synthesizeMouse(anchor, 2, 2, {}, hud.iframeWindow);
-  await onScratchpadSelected;
+  yield onScratchpadSelected;
 
   is(toolbox.getCurrentPanel(), scratchpadPanel,
     "Clicking link switches to Scratchpad panel");
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_loglimit.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_loglimit.js
index 5647d7cbb54d..a248e8cd1b46 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_loglimit.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_loglimit.js
@@ -16,7 +16,7 @@ add_task(async function () {
   hud.jsterm.clearOutput();
 
   let onMessage = waitForMessage(hud, "test message [149]");
-  ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+  ContentTask.spawn(gBrowser.selectedBrowser, {}, function* () {
     for (let i = 0; i < 150; i++) {
       content.console.log(`test message [${i}]`);
     }
@@ -29,7 +29,7 @@ add_task(async function () {
   is(findMessages(hud, "").length, 140, "Number of displayed messages is correct");
 
   onMessage = waitForMessage(hud, "hello world");
-  ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+  ContentTask.spawn(gBrowser.selectedBrowser, {}, function* () {
     content.console.log("hello world");
   });
   await onMessage;
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_expand.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_expand.js
index 0c8d608f5686..8e7d0deac61c 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_expand.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_expand.js
@@ -12,7 +12,7 @@
 const TEST_URI = "data:text/html;charset=utf8,test for bug 787981 - check " +
                  "that long strings can be expanded in the output.";
 
-add_task(async function () {
+add_task(function* () {
   let { DebuggerServer } = require("devtools/server/main");
 
   let longString = (new Array(DebuggerServer.LONG_STRING_LENGTH + 4))
@@ -20,14 +20,14 @@ add_task(async function () {
   let initialString =
     longString.substring(0, DebuggerServer.LONG_STRING_INITIAL_LENGTH);
 
-  await loadTab(TEST_URI);
+  yield loadTab(TEST_URI);
 
-  let hud = await openConsole();
+  let hud = yield openConsole();
 
   hud.jsterm.clearOutput(true);
   hud.jsterm.execute("console.log('bazbaz', '" + longString + "', 'boom')");
 
-  let [result] = await waitForMessages({
+  let [result] = yield waitForMessages({
     webconsole: hud,
     messages: [{
       name: "console.log output",
@@ -44,7 +44,7 @@ add_task(async function () {
 
   EventUtils.synthesizeMouse(clickable, 2, 2, {}, hud.iframeWindow);
 
-  await waitForMessages({
+  yield waitForMessages({
     webconsole: hud,
     messages: [{
       name: "full string",
@@ -55,7 +55,7 @@ add_task(async function () {
   });
 
   hud.jsterm.clearOutput(true);
-  let msg = await execute(hud, "'" + longString + "'");
+  let msg = yield execute(hud, "'" + longString + "'");
 
   isnot(msg.textContent.indexOf(initialString), -1,
       "initial string is shown");
@@ -69,7 +69,7 @@ add_task(async function () {
 
   EventUtils.synthesizeMouse(clickable, 3, 4, {}, hud.iframeWindow);
 
-  await waitForMessages({
+  yield waitForMessages({
     webconsole: hud,
     messages: [{
       name: "full string",
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_hang.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_hang.js
index 5a864259771d..375b33397503 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_hang.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_longstring_hang.js
@@ -13,14 +13,14 @@ const TEST_URI = "http://example.com/browser/devtools/client/webconsole/" +
                  "new-console-output/test/mochitest/" +
                  "test-bug-859170-longstring-hang.html";
 
-add_task(async function () {
-  await loadTab(TEST_URI);
+add_task(function* () {
+  yield loadTab(TEST_URI);
 
-  let hud = await openConsole();
+  let hud = yield openConsole();
 
   info("wait for the initial long string");
 
-  let results = await waitForMessages({
+  let results = yield waitForMessages({
     webconsole: hud,
     messages: [
       {
@@ -41,7 +41,7 @@ add_task(async function () {
 
   info("wait for long string expansion");
 
-  await waitForMessages({
+  yield waitForMessages({
     webconsole: hud,
     messages: [
       {
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_message_categories.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_message_categories.js
index ebce7a411ce8..080790c118e3 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_message_categories.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_message_categories.js
@@ -30,7 +30,7 @@ const TESTS = [
     category: "HTML",
     matchString: "multipart/form-data",
     onload: function () {
-      ContentTask.spawn(gBrowser.selectedBrowser, null, async function () {
+      ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
         let form = content.document.querySelector("form");
         form.submit();
       });
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_object_inspector_while_debugging_and_inspecting.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_object_inspector_while_debugging_and_inspecting.js
index 7eab1b44e961..7f437a5ffab5 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_object_inspector_while_debugging_and_inspecting.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_object_inspector_while_debugging_and_inspecting.js
@@ -73,7 +73,7 @@ async function waitForFrameAdded() {
   info("Waiting for framesadded");
   await new Promise(resolve => {
     thread.addOneTimeListener("framesadded", resolve);
-    ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+    ContentTask.spawn(gBrowser.selectedBrowser, {}, function* () {
       content.wrappedJSObject.firstCall();
     });
   });
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_optimized_out_vars.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_optimized_out_vars.js
index b1104417d157..a77514eb4740 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_optimized_out_vars.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_optimized_out_vars.js
@@ -29,7 +29,7 @@ add_task(async function () {
   let fetchedScopes = debuggerPanel.panelWin.once(FETCHED_SCOPES);
 
   // Cause the debuggee to pause
-  ContentTask.spawn(gBrowser.selectedBrowser, {}, async function () {
+  ContentTask.spawn(gBrowser.selectedBrowser, {}, function* () {
     let button = content.document.querySelector("button");
     button.click();
   });
diff --git a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_stacktrace_location_scratchpad_link.js b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_stacktrace_location_scratchpad_link.js
index 1a3f36ba6d92..60bb1d006614 100644
--- a/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_stacktrace_location_scratchpad_link.js
+++ b/devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_stacktrace_location_scratchpad_link.js
@@ -7,14 +7,14 @@
 
 const TEST_URI = "data:text/html;charset=utf8,<p>test stacktrace scratchpad linking</p>";
 
-add_task(async function () {
-  await pushPref("devtools.scratchpad.enabled", true);
-  await openNewTabAndToolbox(TEST_URI);
+add_task(function* () {
+  yield pushPref("devtools.scratchpad.enabled", true);
+  yield openNewTabAndToolbox(TEST_URI);
 
   info("Opening toolbox with Scratchpad panel");
 
   let target = TargetFactory.forTab(gBrowser.selectedTab);
-  let toolbox = await gDevTools.showToolbox(target, "scratchpad", "window");
+  let toolbox = yield gDevTools.showToolbox(target, "scratchpad", "window");
 
   let scratchpadPanel = toolbox.getPanel("scratchpad");
   let { scratchpad } = scratchpadPanel;
@@ -23,7 +23,7 @@ add_task(async function () {
 
   info("Switching to webconsole panel");
 
-  let webconsolePanel = await toolbox.selectTool("webconsole");
+  let webconsolePanel = yield toolbox.selectTool("webconsole");
   let { hud } = webconsolePanel;
   is(toolbox.getCurrentPanel(), webconsolePanel,
     "Webconsole is currently selected panel");
@@ -42,7 +42,7 @@ add_task(async function () {
     foo();
   `);
   scratchpad.run();
-  let message = await waitFor(() => findMessage(hud, "console.trace()"));
+  let message = yield waitFor(() => findMessage(hud, "console.trace()"));
 
   info("Clicking link to switch to and focus Scratchpad");
 
@@ -52,7 +52,7 @@ add_task(async function () {
   let onScratchpadSelected = toolbox.once("scratchpad-selected");
 
   EventUtils.synthesizeMouse(anchor, 2, 2, {}, hud.iframeWindow);
-  await onScratchpadSelected;
+  yield onScratchpadSelected;
 
   is(toolbox.getCurrentPanel(), scratchpadPanel,
     "Clicking link in stacktrace switches to Scratchpad panel");
diff --git a/devtools/client/webide/content/webide.js b/devtools/client/webide/content/webide.js
index d66a78acfbfa..03c5a3270575 100644
--- a/devtools/client/webide/content/webide.js
+++ b/devtools/client/webide/content/webide.js
@@ -18,6 +18,7 @@ const utils = require("devtools/client/webide/modules/utils");
 const Telemetry = require("devtools/client/shared/telemetry");
 const {RuntimeScanners} = require("devtools/client/webide/modules/runtimes");
 const {showDoorhanger} = require("devtools/client/shared/doorhanger");
+const {Task} = require("devtools/shared/task");
 
 const Strings = Services.strings.createBundle("chrome://devtools/locale/webide.properties");
 
@@ -140,16 +141,16 @@ var UI = {
         this.updateConnectionTelemetry();
         break;
       case "project":
-        this._updatePromise = (async function () {
+        this._updatePromise = Task.spawn(function* () {
           UI.updateTitle();
-          await UI.destroyToolbox();
+          yield UI.destroyToolbox();
           UI.updateCommands();
           UI.openProject();
-          await UI.autoStartProject();
+          yield UI.autoStartProject();
           UI.autoOpenToolbox();
           UI.saveLastSelectedProject();
           UI.updateRemoveProjectButton();
-        })();
+        });
         return;
       case "project-started":
         this.updateCommands();
@@ -560,7 +561,7 @@ var UI = {
     this.selectDeckPanel("details");
   },
 
-  async autoStartProject() {
+  autoStartProject: Task.async(function* () {
     let project = AppManager.selectedProject;
 
     if (!project) {
@@ -575,11 +576,11 @@ var UI = {
     // Do not force opening apps that are already running, as they may have
     // some activity being opened and don't want to dismiss them.
     if (project.type == "runtimeApp" && !AppManager.isProjectRunning()) {
-      await UI.busyUntil(AppManager.launchRuntimeApp(), "running app");
+      yield UI.busyUntil(AppManager.launchRuntimeApp(), "running app");
     }
-  },
+  }),
 
-  async autoOpenToolbox() {
+  autoOpenToolbox: Task.async(function* () {
     let project = AppManager.selectedProject;
 
     if (!project) {
@@ -591,14 +592,14 @@ var UI = {
       return; // For something that is not an editable app, we're done.
     }
 
-    await UI.createToolbox();
-  },
+    yield UI.createToolbox();
+  }),
 
-  async importAndSelectApp(source) {
+  importAndSelectApp: Task.async(function* (source) {
     let isPackaged = !!source.path;
     let project;
     try {
-      project = await AppProjects[isPackaged ? "addPackaged" : "addHosted"](source);
+      project = yield AppProjects[isPackaged ? "addPackaged" : "addHosted"](source);
     } catch (e) {
       if (e === "Already added") {
         // Select project that's already been added,
@@ -613,7 +614,7 @@ var UI = {
     AppManager.selectedProject = project;
 
     this._telemetry.actionOccurred("webideImportProject");
-  },
+  }),
 
   // Remember the last selected project on the runtime
   saveLastSelectedProject: function () {
@@ -733,10 +734,10 @@ var UI = {
     deck.selectedPanel = null;
   },
 
-  async checkRuntimeVersion() {
+  checkRuntimeVersion: Task.async(function* () {
     if (AppManager.connected) {
       let { client } = AppManager.connection;
-      let report = await client.checkRuntimeVersion(AppManager.listTabsForm);
+      let report = yield client.checkRuntimeVersion(AppManager.listTabsForm);
       if (report.incompatible == "too-recent") {
         this.reportError("error_runtimeVersionTooRecent", report.runtimeID,
           report.localID);
@@ -746,7 +747,7 @@ var UI = {
           report.minVersion);
       }
     }
-  },
+  }),
 
   /** ******** TOOLBOX **********/
 
@@ -852,10 +853,10 @@ var Cmds = {
   },
 
   disconnectRuntime: function () {
-    let disconnecting = (async function () {
-      await UI.destroyToolbox();
-      await AppManager.disconnectRuntime();
-    })();
+    let disconnecting = Task.spawn(function* () {
+      yield UI.destroyToolbox();
+      yield AppManager.disconnectRuntime();
+    });
     return UI.busyUntil(disconnecting, "disconnecting from runtime");
   },
 
@@ -877,7 +878,7 @@ var Cmds = {
     UI.selectDeckPanel("devicepreferences");
   },
 
-  async play() {
+  play: Task.async(function* () {
     let busy;
     switch (AppManager.selectedProject.type) {
       case "packaged":
@@ -900,7 +901,7 @@ var Cmds = {
     }
     UI.onAction("play");
     return busy;
-  },
+  }),
 
   stop: function () {
     return UI.busyUntil(AppManager.stopRunningApp(), "stopping app");
diff --git a/devtools/client/webide/modules/app-manager.js b/devtools/client/webide/modules/app-manager.js
index c961b89a1884..b886fe23f8f1 100644
--- a/devtools/client/webide/modules/app-manager.js
+++ b/devtools/client/webide/modules/app-manager.js
@@ -15,6 +15,7 @@ const {AppValidator} = require("devtools/client/webide/modules/app-validator");
 const {ConnectionManager, Connection} = require("devtools/shared/client/connection-manager");
 const {getDeviceFront} = require("devtools/shared/fronts/device");
 const {getPreferenceFront} = require("devtools/shared/fronts/preference");
+const {Task} = require("devtools/shared/task");
 const {RuntimeScanners, RuntimeTypes} = require("devtools/client/webide/modules/runtimes");
 const {NetUtil} = require("resource://gre/modules/NetUtil.jsm");
 const Telemetry = require("devtools/client/shared/telemetry");
@@ -274,14 +275,14 @@ var AppManager = exports.AppManager = {
       return Promise.reject("Can't find app front for selected project");
     }
 
-    return (async function () {
+    return Task.spawn(function* () {
       // Once we asked the app to launch, the app isn't necessary completely loaded.
       // launch request only ask the app to launch and immediatly returns.
       // We have to keep trying to get app tab actors required to create its target.
 
       for (let i = 0; i < 10; i++) {
         try {
-          return await app.getTarget();
+          return yield app.getTarget();
         } catch (e) {}
         return new Promise(resolve => {
           setTimeout(resolve, 500);
@@ -290,7 +291,7 @@ var AppManager = exports.AppManager = {
 
       AppManager.reportError("error_cantConnectToApp", app.manifest.manifestURL);
       throw new Error("can't connect to app");
-    })();
+    });
   },
 
   getProjectManifestURL: function (project) {
@@ -373,7 +374,7 @@ var AppManager = exports.AppManager = {
     return this._selectedProject;
   },
 
-  async removeSelectedProject() {
+  removeSelectedProject: Task.async(function* () {
     let location = this.selectedProject.location;
     AppManager.selectedProject = null;
     // If the user cancels the removeProject operation, don't remove the project
@@ -381,9 +382,9 @@ var AppManager = exports.AppManager = {
       return;
     }
 
-    await AppProjects.remove(location);
+    yield AppProjects.remove(location);
     AppManager.update("project-removed");
-  },
+  }),
 
   _selectedRuntime: null,
   set selectedRuntime(value) {
@@ -462,7 +463,7 @@ var AppManager = exports.AppManager = {
     return deferred;
   },
 
-  async _recordRuntimeInfo() {
+  _recordRuntimeInfo: Task.async(function* () {
     if (!this.connected) {
       return;
     }
@@ -475,7 +476,7 @@ var AppManager = exports.AppManager = {
       this.update("runtime-telemetry");
       return;
     }
-    let d = await this.deviceFront.getDescription();
+    let d = yield this.deviceFront.getDescription();
     this._telemetry.logKeyed("DEVTOOLS_WEBIDE_CONNECTED_RUNTIME_PROCESSOR",
                              d.processor, true);
     this._telemetry.logKeyed("DEVTOOLS_WEBIDE_CONNECTED_RUNTIME_OS",
@@ -487,7 +488,7 @@ var AppManager = exports.AppManager = {
     this._telemetry.logKeyed("DEVTOOLS_WEBIDE_CONNECTED_RUNTIME_VERSION",
                              d.version, true);
     this.update("runtime-telemetry");
-  },
+  }),
 
   isMainProcessDebuggable: function () {
     // Fx <39 exposes chrome tab actors on RootActor
@@ -570,11 +571,11 @@ var AppManager = exports.AppManager = {
       return Promise.reject("Can't install");
     }
 
-    return (async function () {
+    return Task.spawn(function* () {
       let self = AppManager;
 
       // Validate project
-      await self.validateAndUpdateProject(project);
+      yield self.validateAndUpdateProject(project);
 
       if (project.errorsCount > 0) {
         self.reportError("error_cantInstallValidationErrors");
@@ -592,7 +593,7 @@ var AppManager = exports.AppManager = {
         let packageDir = project.location;
         console.log("Installing app from " + packageDir);
 
-        response = await self._appsFront.installPackaged(packageDir,
+        response = yield self._appsFront.installPackaged(packageDir,
                                                          project.packagedAppOrigin);
 
         // If the packaged app specified a custom origin override,
@@ -610,7 +611,7 @@ var AppManager = exports.AppManager = {
           origin: origin.spec,
           manifestURL: project.location
         };
-        response = await self._appsFront.installHosted(appId,
+        response = yield self._appsFront.installHosted(appId,
                                             metadata,
                                             project.manifest);
       }
@@ -631,12 +632,12 @@ var AppManager = exports.AppManager = {
             }
           });
         });
-        await app.launch();
-        await deferred;
+        yield app.launch();
+        yield deferred;
       } else {
-        await app.reload();
+        yield app.reload();
       }
-    })();
+    });
   },
 
   stopRunningApp: function () {
@@ -651,7 +652,7 @@ var AppManager = exports.AppManager = {
       return Promise.reject();
     }
 
-    return (async function () {
+    return Task.spawn(function* () {
 
       let packageDir = project.location;
       let validation = new AppValidator({
@@ -660,7 +661,7 @@ var AppManager = exports.AppManager = {
         location: packageDir
       });
 
-      await validation.validate();
+      yield validation.validate();
 
       if (validation.manifest) {
         let manifest = validation.manifest;
@@ -722,15 +723,15 @@ var AppManager = exports.AppManager = {
       }
 
       if (project.type === "hosted" && project.location !== validation.manifestURL) {
-        await AppProjects.updateLocation(project, validation.manifestURL);
+        yield AppProjects.updateLocation(project, validation.manifestURL);
       } else if (AppProjects.get(project.location)) {
-        await AppProjects.update(project);
+        yield AppProjects.update(project);
       }
 
       if (AppManager.selectedProject === project) {
         AppManager.update("project-validated");
       }
-    })();
+    });
   },
 
   /* RUNTIME LIST */
diff --git a/devtools/client/webide/modules/app-validator.js b/devtools/client/webide/modules/app-validator.js
index ad6c7f40ae87..1cc0a8c87614 100644
--- a/devtools/client/webide/modules/app-validator.js
+++ b/devtools/client/webide/modules/app-validator.js
@@ -7,6 +7,7 @@ var {Ci, Cu} = require("chrome");
 
 const {FileUtils} = require("resource://gre/modules/FileUtils.jsm");
 const Services = require("Services");
+const {Task} = require("devtools/shared/task");
 var strings = Services.strings.createBundle("chrome://devtools/locale/app-manager.properties");
 
 function AppValidator({ type, location }) {
@@ -118,16 +119,16 @@ AppValidator.findManifestPath = function (manifestURL) {
 };
 
 AppValidator.checkAlternateManifest = function (manifestURL) {
-  return (async function () {
+  return Task.spawn(function* () {
     let result;
     try {
-      result = await AppValidator.findManifestPath(manifestURL);
+      result = yield AppValidator.findManifestPath(manifestURL);
     } catch (e) {
-      result = await AppValidator.findManifestAtOrigin(manifestURL);
+      result = yield AppValidator.findManifestAtOrigin(manifestURL);
     }
 
     return result;
-  })();
+  });
 };
 
 AppValidator.prototype._fetchManifest = function (manifestURL) {
diff --git a/devtools/client/webide/modules/project-list.js b/devtools/client/webide/modules/project-list.js
index 542d927683ca..a07ab36875b9 100644
--- a/devtools/client/webide/modules/project-list.js
+++ b/devtools/client/webide/modules/project-list.js
@@ -8,6 +8,7 @@ const Services = require("Services");
 const {AppProjects} = require("devtools/client/webide/modules/app-projects");
 const {AppManager} = require("devtools/client/webide/modules/app-manager");
 const EventEmitter = require("devtools/shared/event-emitter");
+const {Task} = require("devtools/shared/task");
 const utils = require("devtools/client/webide/modules/utils");
 const Telemetry = require("devtools/client/shared/telemetry");
 
@@ -68,7 +69,7 @@ ProjectList.prototype = {
   newApp: function (testOptions) {
     let parentWindow = this._parentWindow;
     let self = this;
-    return this._UI.busyUntil((async function () {
+    return this._UI.busyUntil(Task.spawn(function* () {
       // Open newapp.xul, which will feed ret.location
       let ret = {location: null, testOptions: testOptions};
       parentWindow.openDialog("chrome://webide/content/newapp.xul", "newapp", "chrome,modal", ret);
@@ -82,36 +83,36 @@ ProjectList.prototype = {
       AppManager.selectedProject = project;
 
       self._telemetry.actionOccurred("webideNewProject");
-    })(), "creating new app");
+    }), "creating new app");
   },
 
   importPackagedApp: function (location) {
     let parentWindow = this._parentWindow;
     let UI = this._UI;
-    return UI.busyUntil((async function () {
-      let directory = await utils.getPackagedDirectory(parentWindow, location);
+    return UI.busyUntil(Task.spawn(function* () {
+      let directory = yield utils.getPackagedDirectory(parentWindow, location);
 
       if (!directory) {
         // User cancelled directory selection
         return;
       }
 
-      await UI.importAndSelectApp(directory);
-    })(), "importing packaged app");
+      yield UI.importAndSelectApp(directory);
+    }), "importing packaged app");
   },
 
   importHostedApp: function (location) {
     let parentWindow = this._parentWindow;
     let UI = this._UI;
-    return UI.busyUntil((async function () {
+    return UI.busyUntil(Task.spawn(function* () {
       let url = utils.getHostedURL(parentWindow, location);
 
       if (!url) {
         return;
       }
 
-      await UI.importAndSelectApp(url);
-    })(), "importing hosted app");
+      yield UI.importAndSelectApp(url);
+    }), "importing hosted app");
   },
 
   /**
diff --git a/devtools/client/webide/modules/runtime-list.js b/devtools/client/webide/modules/runtime-list.js
index f29a7ca9eeac..3370956c86f2 100644
--- a/devtools/client/webide/modules/runtime-list.js
+++ b/devtools/client/webide/modules/runtime-list.js
@@ -9,6 +9,7 @@ const {AppManager} = require("devtools/client/webide/modules/app-manager");
 const EventEmitter = require("devtools/shared/event-emitter");
 const {RuntimeScanners, WiFiScanner} = require("devtools/client/webide/modules/runtimes");
 const {Devices} = require("resource://devtools/shared/apps/Devices.jsm");
+const {Task} = require("devtools/shared/task");
 const utils = require("devtools/client/webide/modules/utils");
 
 const Strings = Services.strings.createBundle("chrome://devtools/locale/webide.properties");
diff --git a/devtools/client/webide/modules/tab-store.js b/devtools/client/webide/modules/tab-store.js
index 034ba37c20db..63f64c3b685b 100644
--- a/devtools/client/webide/modules/tab-store.js
+++ b/devtools/client/webide/modules/tab-store.js
@@ -7,6 +7,7 @@ const { Cu } = require("chrome");
 const { TargetFactory } = require("devtools/client/framework/target");
 const EventEmitter = require("devtools/shared/event-emitter");
 const { Connection } = require("devtools/shared/client/connection-manager");
+const { Task } = require("devtools/shared/task");
 
 const _knownTabStores = new WeakMap();
 
@@ -154,18 +155,18 @@ TabStore.prototype = {
       return this._selectedTabTargetPromise;
     }
     let store = this;
-    this._selectedTabTargetPromise = (async function () {
+    this._selectedTabTargetPromise = Task.spawn(function* () {
       // If you connect to a tab, then detach from it, the root actor may have
       // de-listed the actors that belong to the tab.  This breaks the toolbox
       // if you try to connect to the same tab again.  To work around this
       // issue, we force a "listTabs" request before connecting to a tab.
-      await store.listTabs();
+      yield store.listTabs();
       return TargetFactory.forRemoteTab({
         form: store._selectedTab,
         client: store._connection.client,
         chrome: false
       });
-    })();
+    });
     this._selectedTabTargetPromise.then(target => {
       target.once("close", () => {
         this._selectedTabTargetPromise = null;
diff --git a/devtools/client/webide/test/browser_tabs.js b/devtools/client/webide/test/browser_tabs.js
index 32b798c5be22..6ddfd29cff9e 100644
--- a/devtools/client/webide/test/browser_tabs.js
+++ b/devtools/client/webide/test/browser_tabs.js
@@ -8,27 +8,27 @@ function test() {
   waitForExplicitFinish();
   requestCompleteLog();
 
-  (async function () {
+  Task.spawn(function* () {
     // Since we test the connections set below, destroy the server in case it
     // was left open.
     DebuggerServer.destroy();
     DebuggerServer.init();
     DebuggerServer.registerAllActors();
 
-    let tab = await addTab(TEST_URI);
+    let tab = yield addTab(TEST_URI);
 
-    let win = await openWebIDE();
+    let win = yield openWebIDE();
     let docProject = getProjectDocument(win);
     let docRuntime = getRuntimeDocument(win);
 
-    await connectToLocal(win, docRuntime);
+    yield connectToLocal(win, docRuntime);
 
     is(Object.keys(DebuggerServer._connections).length, 1, "Locally connected");
 
-    await selectTabProject(win, docProject);
+    yield selectTabProject(win, docProject);
 
     ok(win.UI.toolboxPromise, "Toolbox promise exists");
-    await win.UI.toolboxPromise;
+    yield win.UI.toolboxPromise;
 
     let project = win.AppManager.selectedProject;
     is(project.location, TEST_URI, "Location is correct");
@@ -37,30 +37,30 @@ function test() {
     // Ensure tab list changes are noticed
     let tabsNode = docProject.querySelector("#project-panel-tabs");
     is(tabsNode.querySelectorAll(".panel-item").length, 2, "2 tabs available");
-    await removeTab(tab);
-    await waitForUpdate(win, "project");
-    await waitForUpdate(win, "runtime-targets");
+    yield removeTab(tab);
+    yield waitForUpdate(win, "project");
+    yield waitForUpdate(win, "runtime-targets");
     is(tabsNode.querySelectorAll(".panel-item").length, 1, "1 tab available");
 
-    tab = await addTab(TEST_URI);
+    tab = yield addTab(TEST_URI);
 
     is(tabsNode.querySelectorAll(".panel-item").length, 2, "2 tabs available");
 
-    await removeTab(tab);
+    yield removeTab(tab);
 
     is(tabsNode.querySelectorAll(".panel-item").length, 2, "2 tabs available");
 
     docProject.querySelector("#refresh-tabs").click();
 
-    await waitForUpdate(win, "runtime-targets");
+    yield waitForUpdate(win, "runtime-targets");
 
     is(tabsNode.querySelectorAll(".panel-item").length, 1, "1 tab available");
 
-    await win.Cmds.disconnectRuntime();
-    await closeWebIDE(win);
+    yield win.Cmds.disconnectRuntime();
+    yield closeWebIDE(win);
 
     DebuggerServer.destroy();
-  })().then(finish, handleError);
+  }).then(finish, handleError);
 }
 
 function connectToLocal(win, docRuntime) {
@@ -73,12 +73,12 @@ function connectToLocal(win, docRuntime) {
 }
 
 function selectTabProject(win, docProject) {
-  return (async function () {
-    await waitForUpdate(win, "runtime-targets");
+  return Task.spawn(function* () {
+    yield waitForUpdate(win, "runtime-targets");
     let tabsNode = docProject.querySelector("#project-panel-tabs");
     let tabNode = tabsNode.querySelectorAll(".panel-item")[1];
     let project = waitForUpdate(win, "project");
     tabNode.click();
-    await project;
-  })();
+    yield project;
+  });
 }
diff --git a/devtools/client/webide/test/device_front_shared.js b/devtools/client/webide/test/device_front_shared.js
index 66f34238e780..0ddb5df21563 100644
--- a/devtools/client/webide/test/device_front_shared.js
+++ b/devtools/client/webide/test/device_front_shared.js
@@ -109,7 +109,7 @@ function addNewFieldInteger() {
   is(customValue.value, "", "Custom integer value reset");
 }
 
-var editFieldInteger = async function () {
+var editFieldInteger = Task.async(function* () {
   // Edit existing custom integer preference
   newField.value = 3;
   newField.click();
@@ -120,7 +120,7 @@ var editFieldInteger = async function () {
   resetBtn.click();
 
   try {
-    await iframe.contentWindow.configView._defaultField;
+    yield iframe.contentWindow.configView._defaultField;
   } catch (err) {
     let fieldRow = doc.querySelector("#row-new-integer-field");
     if (!fieldRow) {
@@ -128,32 +128,32 @@ var editFieldInteger = async function () {
     }
     ok(!found, "Custom field removed");
   }
-};
+});
 
-var resetExistingField = async function (id) {
+var resetExistingField = Task.async(function* (id) {
   let existing = doc.getElementById(id);
   existing.click();
   is(existing.checked, true, "Existing boolean value is correct");
   resetBtn = doc.getElementById("btn-" + id);
   resetBtn.click();
 
-  await iframe.contentWindow.configView._defaultField;
+  yield iframe.contentWindow.configView._defaultField;
 
   ok(resetBtn.classList.contains("hide"), true, "Reset button hidden");
   is(existing.checked, true, "Existing field reset");
-};
+});
 
-var resetNewField = async function (id) {
+var resetNewField = Task.async(function* (id) {
   let custom = doc.getElementById(id);
   custom.click();
   is(custom.value, "test", "New string value is correct");
   resetBtn = doc.getElementById("btn-" + id);
   resetBtn.click();
 
-  await iframe.contentWindow.configView._defaultField;
+  yield iframe.contentWindow.configView._defaultField;
 
   ok(resetBtn.classList.contains("hide"), true, "Reset button hidden");
-};
+});
 
 function addNewFieldBoolean() {
   customValueType.value = "boolean";
diff --git a/devtools/client/webide/test/head.js b/devtools/client/webide/test/head.js
index 7c49b767506a..cc9998d65fd7 100644
--- a/devtools/client/webide/test/head.js
+++ b/devtools/client/webide/test/head.js
@@ -7,6 +7,7 @@ const { require } = ChromeUtils.import("resource://devtools/shared/Loader.jsm",
 const { FileUtils } = require("resource://gre/modules/FileUtils.jsm");
 const { gDevTools } = require("devtools/client/framework/devtools");
 const Services = require("Services");
+const { Task } = require("devtools/shared/task");
 const { AppProjects } = require("devtools/client/webide/modules/app-projects");
 const DevToolsUtils = require("devtools/shared/DevToolsUtils");
 const { DebuggerServer } = require("devtools/server/main");
@@ -39,7 +40,7 @@ registerCleanupFunction(() => {
   Services.prefs.clearUserPref("devtools.webide.lastConnectedRuntime");
 });
 
-var openWebIDE = async function (autoInstallAddons) {
+var openWebIDE = Task.async(function* (autoInstallAddons) {
   info("opening WebIDE");
 
   Services.prefs.setBoolPref("devtools.webide.autoinstallADBHelper", !!autoInstallAddons);
@@ -47,7 +48,7 @@ var openWebIDE = async function (autoInstallAddons) {
   let ww = Cc["@mozilla.org/embedcomp/window-watcher;1"].getService(Ci.nsIWindowWatcher);
   let win = ww.openWindow(null, "chrome://webide/content/", "webide", "chrome,centerscreen,resizable", null);
 
-  await new Promise(resolve => {
+  yield new Promise(resolve => {
     win.addEventListener("load", function () {
       SimpleTest.requestCompleteLog();
       SimpleTest.executeSoon(resolve);
@@ -57,7 +58,7 @@ var openWebIDE = async function (autoInstallAddons) {
   info("WebIDE open");
 
   return win;
-};
+});
 
 function closeWebIDE(win) {
   info("Closing WebIDE");
@@ -73,15 +74,15 @@ function closeWebIDE(win) {
 }
 
 function removeAllProjects() {
-  return (async function () {
-    await AppProjects.load();
+  return Task.spawn(function* () {
+    yield AppProjects.load();
     // use a new array so we're not iterating over the same
     // underlying array that's being modified by AppProjects
     let projects = AppProjects.projects.map(p => p.location);
     for (let i = 0; i < projects.length; i++) {
-      await AppProjects.remove(projects[i]);
+      yield AppProjects.remove(projects[i]);
     }
-  })();
+  });
 }
 
 function nextTick() {
diff --git a/devtools/client/webide/test/test_addons.html b/devtools/client/webide/test/test_addons.html
index 632ad945d44e..1628d4ae66b2 100644
--- a/devtools/client/webide/test/test_addons.html
+++ b/devtools/client/webide/test/test_addons.html
@@ -40,22 +40,22 @@
           });
         }
 
-        (async function () {
+        Task.spawn(function*() {
 
           ok(!Devices.helperAddonInstalled, "Helper not installed");
 
-          let win = await openWebIDE(true);
+          let win = yield openWebIDE(true);
           let docRuntime = getRuntimeDocument(win);
 
           ok(Devices.helperAddonInstalled, "Helper has been auto-installed");
 
-          await nextTick();
+          yield nextTick();
 
           let w = addonDoc.querySelector(".warning");
           let display = addonDoc.defaultView.getComputedStyle(w).display
           is(display, "none", "Warning about missing ADB hidden");
 
-          await uninstallADBFromUI(addonDoc, "adb");
+          yield uninstallADBFromUI(addonDoc, "adb");
 
           items = panelNode.querySelectorAll(".runtime-panel-item-usb");
           is(items.length, 0, "No usb runtime listed");
@@ -63,11 +63,11 @@
           display = addonDoc.defaultView.getComputedStyle(w).display
           is(display, "block", "Warning about missing ADB present");
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
           SimpleTest.finish();
 
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_autoconnect_runtime.html b/devtools/client/webide/test/test_autoconnect_runtime.html
index 98e522e544f8..9965228b6206 100644
--- a/devtools/client/webide/test/test_autoconnect_runtime.html
+++ b/devtools/client/webide/test/test_autoconnect_runtime.html
@@ -18,11 +18,11 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
+        Task.spawn(function*() {
           DebuggerServer.init();
           DebuggerServer.registerAllActors();
 
-          let win = await openWebIDE();
+          let win = yield openWebIDE();
           let docRuntime = getRuntimeDocument(win);
 
           let fakeRuntime = {
@@ -53,39 +53,39 @@
           items[0].click();
 
           ok(win.document.querySelector("window").className, "busy", "UI is busy");
-          await win.UI._busyPromise;
+          yield win.UI._busyPromise;
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 2, "Connected");
 
           connectionsChanged = waitForConnectionChange("closed", 2);
 
-          await nextTick();
-          await closeWebIDE(win);
+          yield nextTick();
+          yield closeWebIDE(win);
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 0, "Disconnected");
 
           connectionsChanged = waitForConnectionChange("opened", 2);
 
-          win = await openWebIDE();
+          win = yield openWebIDE();
 
           win.AppManager.runtimeList.usb.push(fakeRuntime);
           win.AppManager.update("runtime-list");
 
-          await waitForUpdate(win, "runtime-targets");
+          yield waitForUpdate(win, "runtime-targets");
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 2, "Automatically reconnected");
 
-          await win.Cmds.disconnectRuntime();
+          yield win.Cmds.disconnectRuntime();
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
           DebuggerServer.destroy();
 
           SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_autoselect_project.html b/devtools/client/webide/test/test_autoselect_project.html
index 44a846e3ec83..da8b828642c8 100644
--- a/devtools/client/webide/test/test_autoselect_project.html
+++ b/devtools/client/webide/test/test_autoselect_project.html
@@ -18,11 +18,11 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
+        Task.spawn(function* () {
           DebuggerServer.init();
           DebuggerServer.registerAllActors();
 
-          let win = await openWebIDE();
+          let win = yield openWebIDE();
           let docRuntime = getRuntimeDocument(win);
           let docProject = getProjectDocument(win);
 
@@ -34,37 +34,37 @@
           let connectionsChanged = waitForConnectionChange("opened", 2);
           items[1].click();
 
-          await waitForUpdate(win, "runtime-targets");
+          yield waitForUpdate(win, "runtime-targets");
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 2, "Locally connected");
 
           ok(win.AppManager.isMainProcessDebuggable(), "Main process available");
 
           // Select main process
-          await win.Cmds.showProjectPanel();
-          await waitForUpdate(win, "runtime-targets");
+          yield win.Cmds.showProjectPanel();
+          yield waitForUpdate(win, "runtime-targets");
           SimpleTest.executeSoon(() => {
             docProject.querySelectorAll("#project-panel-runtimeapps .panel-item")[0].click();
           });
 
-          await waitForUpdate(win, "project");
+          yield waitForUpdate(win, "project");
 
           let lastProject = Services.prefs.getCharPref("devtools.webide.lastSelectedProject");
           is(lastProject, "mainProcess:", "Last project is main process");
 
           connectionsChanged = waitForConnectionChange("closed", 2);
 
-          await nextTick();
-          await closeWebIDE(win);
+          yield nextTick();
+          yield closeWebIDE(win);
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 0, "Disconnected");
 
           connectionsChanged = waitForConnectionChange("opened", 2);
 
           // Re-open, should reselect main process after connection
-          win = await openWebIDE();
+          win = yield openWebIDE();
 
           docRuntime = getRuntimeDocument(win);
 
@@ -75,15 +75,15 @@
           // Connect to local runtime
           items[1].click();
 
-          await waitForUpdate(win, "runtime-targets");
+          yield waitForUpdate(win, "runtime-targets");
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 2, "Locally connected");
           ok(win.AppManager.isMainProcessDebuggable(), "Main process available");
           is(win.AppManager.selectedProject.type, "mainProcess", "Main process reselected");
 
           // Wait for the toolbox to be fully loaded
-          await win.UI.toolboxPromise;
+          yield win.UI.toolboxPromise;
 
           // If we happen to pass a project object targeting the same context,
           // here, the main process, the `selectedProject` attribute shouldn't be updated
@@ -94,14 +94,14 @@
           };
           is(win.AppManager.selectedProject, oldProject, "AppManager.selectedProject shouldn't be updated if we selected the same project");
 
-          await win.Cmds.disconnectRuntime();
+          yield win.Cmds.disconnectRuntime();
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
           DebuggerServer.destroy();
 
           SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_basic.html b/devtools/client/webide/test/test_basic.html
index f0e40dafde01..30229c16be3e 100644
--- a/devtools/client/webide/test/test_basic.html
+++ b/devtools/client/webide/test/test_basic.html
@@ -18,11 +18,11 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
-            let win = await openWebIDE();
+        Task.spawn(function* () {
+            let win = yield openWebIDE();
 
             const {gDevToolsBrowser} = require("devtools/client/framework/devtools-browser");
-            await gDevToolsBrowser.isWebIDEInitialized.promise;
+            yield gDevToolsBrowser.isWebIDEInitialized.promise;
             ok(true, "WebIDE was initialized");
 
             ok(win, "Found a window");
@@ -41,15 +41,15 @@
               });
             });
             try {
-              await win.UI.busyUntil(deferred, "xx");
+              yield win.UI.busyUntil(deferred, "xx");
             } catch(e) {/* This *will* fail */}
             notification =  nbox.getNotificationWithValue("webide:errornotification");
             ok(notification, "Error has been reported");
 
-            await closeWebIDE(win);
+            yield closeWebIDE(win);
 
             SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_device_preferences.html b/devtools/client/webide/test/test_device_preferences.html
index 14a9799a7d3f..973c96d18045 100644
--- a/devtools/client/webide/test/test_device_preferences.html
+++ b/devtools/client/webide/test/test_device_preferences.html
@@ -18,18 +18,18 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
+        Task.spawn(function* () {
           DebuggerServer.init();
           DebuggerServer.registerAllActors();
 
-          let win = await openWebIDE();
+          let win = yield openWebIDE();
 
           let prefIframe = win.document.querySelector("#deck-panel-devicepreferences");
           let docRuntime = getRuntimeDocument(win);
 
           win.AppManager.update("runtime-list");
 
-          await connectToLocalRuntime(win);
+          yield connectToLocalRuntime(win);
 
           let prefs = docRuntime.querySelector("#runtime-preferences");
 
@@ -40,11 +40,11 @@
           win.Cmds.showDevicePrefs();
           is(deck.selectedPanel, prefIframe, "device preferences iframe selected");
 
-          await nextTick();
+          yield nextTick();
 
-          await lazyIframeIsLoaded(prefIframe);
+          yield lazyIframeIsLoaded(prefIframe);
 
-          await prefIframe.contentWindow.getAllPrefs;
+          yield prefIframe.contentWindow.getAllPrefs;
 
           setDocument(prefIframe);
 
@@ -62,9 +62,9 @@
 
           addNewFieldInteger();
 
-          await editFieldInteger();
+          yield editFieldInteger();
 
-          await resetExistingField("accessibility.accesskeycausesactivation");
+          yield resetExistingField("accessibility.accesskeycausesactivation");
 
           addNewFieldBoolean();
 
@@ -72,10 +72,10 @@
 
           DebuggerServer.destroy();
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
           SimpleTest.finish();
-        })().catch(e => {
+        }).catch(e => {
           ok(false, "Exception: " + e);
           SimpleTest.finish();
         });
diff --git a/devtools/client/webide/test/test_device_runtime.html b/devtools/client/webide/test/test_device_runtime.html
index 85934d73339d..3c010b0217dd 100644
--- a/devtools/client/webide/test/test_device_runtime.html
+++ b/devtools/client/webide/test/test_device_runtime.html
@@ -18,15 +18,15 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
+        Task.spawn(function* () {
           DebuggerServer.init();
           DebuggerServer.registerAllActors();
 
-          let win = await openWebIDE();
+          let win = yield openWebIDE();
 
           let detailsIframe = win.document.querySelector("#deck-panel-runtimedetails");
 
-          await connectToLocalRuntime(win);
+          yield connectToLocalRuntime(win);
 
           let details = win.document.querySelector("#cmd_showRuntimeDetails");
 
@@ -37,11 +37,11 @@
           win.Cmds.showRuntimeDetails();
           is(deck.selectedPanel, detailsIframe, "info iframe selected");
 
-          await nextTick();
+          yield nextTick();
 
-          await lazyIframeIsLoaded(detailsIframe);
+          yield lazyIframeIsLoaded(detailsIframe);
 
-          await detailsIframe.contentWindow.getDescriptionPromise;
+          yield detailsIframe.contentWindow.getDescriptionPromise;
 
           // device info and permissions content is checked in other tests
           // We just test one value to make sure we get something
@@ -66,10 +66,10 @@
 
           DebuggerServer.destroy();
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
           SimpleTest.finish();
-        })().catch(e => {
+        }).catch(e => {
           ok(false, "Exception: " + e);
           SimpleTest.finish();
         });
diff --git a/devtools/client/webide/test/test_duplicate_import.html b/devtools/client/webide/test/test_duplicate_import.html
index 34a1f4a8a693..cb9f4b172d87 100644
--- a/devtools/client/webide/test/test_duplicate_import.html
+++ b/devtools/client/webide/test/test_duplicate_import.html
@@ -17,42 +17,42 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
-          let win = await openWebIDE();
+        Task.spawn(function*() {
+          let win = yield openWebIDE();
           let docProject = getProjectDocument(win);
           let winProject = getProjectWindow(win);
           let packagedAppLocation = getTestFilePath("app");
           let hostedAppManifest = TEST_BASE + "hosted_app.manifest";
 
-          await win.AppProjects.load();
+          yield win.AppProjects.load();
           is(win.AppProjects.projects.length, 0, "IDB is empty");
 
           let onValidated = waitForUpdate(win, "project-validated");
           let onDetails = waitForUpdate(win, "details");
-          await winProject.projectList.importPackagedApp(packagedAppLocation);
-          await onValidated;
-          await onDetails;
+          yield winProject.projectList.importPackagedApp(packagedAppLocation);
+          yield onValidated;
+          yield onDetails;
 
-          await winProject.projectList.importHostedApp(hostedAppManifest);
-          await waitForUpdate(win, "project-validated");
-          await nextTick();
+          yield winProject.projectList.importHostedApp(hostedAppManifest);
+          yield waitForUpdate(win, "project-validated");
+          yield nextTick();
 
           onValidated = waitForUpdate(win, "project-validated");
           onDetails = waitForUpdate(win, "details");
-          await winProject.projectList.importPackagedApp(packagedAppLocation);
-          await onValidated;
-          await onDetails;
+          yield winProject.projectList.importPackagedApp(packagedAppLocation);
+          yield onValidated;
+          yield onDetails;
 
           let project = win.AppManager.selectedProject;
           is(project.location, packagedAppLocation, "Correctly reselected existing packaged app.");
-          await nextTick();
+          yield nextTick();
 
           info("to call importHostedApp(" + hostedAppManifest + ") again");
-          await winProject.projectList.importHostedApp(hostedAppManifest);
-          await waitForUpdate(win, "project-validated");
+          yield winProject.projectList.importHostedApp(hostedAppManifest);
+          yield waitForUpdate(win, "project-validated");
           project = win.AppManager.selectedProject;
           is(project.location, hostedAppManifest, "Correctly reselected existing hosted app.");
-          await nextTick();
+          yield nextTick();
 
           let panelNode = docProject.querySelector("#project-panel");
           let items = panelNode.querySelectorAll(".panel-item");
@@ -61,12 +61,12 @@
           is(items[3].querySelector("span").textContent, "A name (in app directory)", "Panel text is correct");
           is(items[4].querySelector("span").textContent, "hosted manifest name property", "Panel text is correct");
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
-          await removeAllProjects();
+          yield removeAllProjects();
 
           SimpleTest.finish();
-        })().catch(e => {
+        }).catch(e => {
           ok(false, "Exception: " + e);
           SimpleTest.finish();
         });
diff --git a/devtools/client/webide/test/test_fullscreenToolbox.html b/devtools/client/webide/test/test_fullscreenToolbox.html
index ce1cdcde1154..1ecdbc8c63e8 100644
--- a/devtools/client/webide/test/test_fullscreenToolbox.html
+++ b/devtools/client/webide/test/test_fullscreenToolbox.html
@@ -27,8 +27,8 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
-          let win = await openWebIDE();
+        Task.spawn(function* () {
+          let win = yield openWebIDE();
           let docProject = getProjectDocument(win);
           let docRuntime = getRuntimeDocument(win);
           win.AppManager.update("runtime-list");
@@ -36,15 +36,15 @@
           connectToLocal(win, docRuntime);
 
           // Select main process
-          await waitForUpdate(win, "runtime-targets");
+          yield waitForUpdate(win, "runtime-targets");
           SimpleTest.executeSoon(() => {
             docProject.querySelectorAll("#project-panel-runtimeapps .panel-item")[0].click();
           });
 
-          await waitForUpdate(win, "project");
+          yield waitForUpdate(win, "project");
 
           ok(win.UI.toolboxPromise, "Toolbox promise exists");
-          await win.UI.toolboxPromise;
+          yield win.UI.toolboxPromise;
 
           let nbox = win.document.querySelector("#notificationbox");
           ok(!nbox.hasAttribute("toolboxfullscreen"), "Toolbox is not fullscreen");
@@ -53,14 +53,14 @@
 
           ok(!nbox.hasAttribute("toolboxfullscreen"), "Toolbox is not fullscreen");
 
-          await win.Cmds.disconnectRuntime();
+          yield win.Cmds.disconnectRuntime();
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
           DebuggerServer.destroy();
 
           SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_import.html b/devtools/client/webide/test/test_import.html
index 4fc9381a50cf..60e8a8b7aa49 100644
--- a/devtools/client/webide/test/test_import.html
+++ b/devtools/client/webide/test/test_import.html
@@ -17,13 +17,13 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
-          let win = await openWebIDE();
+        Task.spawn(function*() {
+          let win = yield openWebIDE();
           let docProject = getProjectDocument(win);
           let winProject = getProjectWindow(win);
           let packagedAppLocation = getTestFilePath("app");
 
-          await win.AppProjects.load();
+          yield win.AppProjects.load();
           is(win.AppProjects.projects.length, 0, "IDB is empty");
 
           info("to call importPackagedApp(" + packagedAppLocation + ")");
@@ -31,9 +31,9 @@
 
           let onValidated = waitForUpdate(win, "project-validated");
           let onDetails = waitForUpdate(win, "details");
-          await winProject.projectList.importPackagedApp(packagedAppLocation);
-          await onValidated;
-          await onDetails;
+          yield winProject.projectList.importPackagedApp(packagedAppLocation);
+          yield onValidated;
+          yield onDetails;
 
           let project = win.AppManager.selectedProject;
           is(project.location, packagedAppLocation, "Location is valid");
@@ -41,21 +41,21 @@
           is(project.manifest.launch_path, "/index.html", "manifest found. launch_path valid.");
           is(project.manifest.description, "desc", "manifest found. description valid");
 
-          await nextTick();
+          yield nextTick();
 
           let hostedAppManifest = TEST_BASE + "hosted_app.manifest";
-          await winProject.projectList.importHostedApp(hostedAppManifest);
-          await waitForUpdate(win, "project-validated");
+          yield winProject.projectList.importHostedApp(hostedAppManifest);
+          yield waitForUpdate(win, "project-validated");
 
           project = win.AppManager.selectedProject;
           is(project.location, hostedAppManifest, "Location is valid");
           is(project.name, "hosted manifest name property", "name field has been updated");
 
-          await nextTick();
+          yield nextTick();
 
           hostedAppManifest = TEST_BASE + "/app";
-          await winProject.projectList.importHostedApp(hostedAppManifest);
-          await waitForUpdate(win, "project-validated");
+          yield winProject.projectList.importHostedApp(hostedAppManifest);
+          yield waitForUpdate(win, "project-validated");
 
           project = win.AppManager.selectedProject;
           ok(project.location.endsWith('manifest.webapp'), "The manifest was found and the project was updated");
@@ -67,12 +67,12 @@
           is(items[3].querySelector("span").textContent, "A name (in app directory)", "Panel text is correct");
           is(items[4].querySelector("span").textContent, "hosted manifest name property", "Panel text is correct");
 
-          await closeWebIDE(win);
+          yield closeWebIDE(win);
 
-          await removeAllProjects();
+          yield removeAllProjects();
 
           SimpleTest.finish();
-        })().catch(e => {
+        }).catch(e => {
           ok(false, "Exception: " + e);
           SimpleTest.finish();
         });
diff --git a/devtools/client/webide/test/test_manifestUpdate.html b/devtools/client/webide/test/test_manifestUpdate.html
index f4e7d630d8c9..0cc5247fd06e 100644
--- a/devtools/client/webide/test/test_manifestUpdate.html
+++ b/devtools/client/webide/test/test_manifestUpdate.html
@@ -20,8 +20,8 @@
 
         let {OS} = ChromeUtils.import("resource://gre/modules/osfile.jsm", {});
 
-        (async function () {
-            let win = await openWebIDE();
+        Task.spawn(function* () {
+            let win = yield openWebIDE();
             let winProject = getProjectWindow(win);
             let AppManager = win.AppManager;
 
@@ -34,9 +34,9 @@
 
             let onValidated = waitForUpdate(win, "project-validated");
             let onDetails = waitForUpdate(win, "details");
-            await winProject.projectList.importPackagedApp(packagedAppLocation);
-            await onValidated;
-            await onDetails;
+            yield winProject.projectList.importPackagedApp(packagedAppLocation);
+            yield onValidated;
+            yield onDetails;
 
             let project = win.AppManager.selectedProject;
 
@@ -50,12 +50,12 @@
             project.manifest.name = "xxx";
 
             // Write to disk
-            await AppManager.writeManifest(project);
+            yield AppManager.writeManifest(project);
 
             // Read file
             let manifestPath = OS.Path.join(packagedAppLocation, "manifest.webapp");
             let Decoder = new TextDecoder();
-            let data = await OS.File.read(manifestPath);
+            let data = yield OS.File.read(manifestPath);
             data = new TextDecoder().decode(data);
             let json = JSON.parse(data);
             is(json.name, "xxx", "manifest written on disc");
@@ -64,11 +64,11 @@
             delete json.name;
             let Encoder = new TextEncoder();
             data = Encoder.encode(JSON.stringify(json));
-            await OS.File.writeAtomic(manifestPath, data , {tmpPath: manifestPath + ".tmp"});
+            yield OS.File.writeAtomic(manifestPath, data , {tmpPath: manifestPath + ".tmp"});
 
             // Trigger validation
-            await AppManager.validateAndUpdateProject(AppManager.selectedProject);
-            await nextTick();
+            yield AppManager.validateAndUpdateProject(AppManager.selectedProject);
+            yield nextTick();
 
             ok(!("name" in project.manifest), "manifest has been updated");
             is(project.name, "--", "Placeholder is used for display name");
@@ -76,22 +76,22 @@
 
             // Make the manifest valid on disk
             project.manifest.name = originalName;
-            await AppManager.writeManifest(project);
+            yield AppManager.writeManifest(project);
 
             // Trigger validation
-            await AppManager.validateAndUpdateProject(AppManager.selectedProject);
-            await nextTick();
+            yield AppManager.validateAndUpdateProject(AppManager.selectedProject);
+            yield nextTick();
 
             ok("name" in project.manifest, "manifest includes name");
             is(project.name, originalName, "Display name uses original manifest name");
             ok(isProjectMarkedAsValid(), "project is marked as valid");
 
-            await closeWebIDE(win);
+            yield closeWebIDE(win);
 
-            await removeAllProjects();
+            yield removeAllProjects();
 
             SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_newapp.html b/devtools/client/webide/test/test_newapp.html
index fc0c19e54dba..d8eb8845a738 100644
--- a/devtools/client/webide/test/test_newapp.html
+++ b/devtools/client/webide/test/test_newapp.html
@@ -18,11 +18,11 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
-          let win = await openWebIDE();
+        Task.spawn(function* () {
+          let win = yield openWebIDE();
           let winProject = getProjectWindow(win);
           let tmpDir = FileUtils.getDir("TmpD", []);
-          await winProject.projectList.newApp({
+          yield winProject.projectList.newApp({
             index: 0,
             name: "webideTmpApp",
             folder: tmpDir
@@ -36,10 +36,10 @@
 
           // Clean up
           tmpDir.remove(true);
-          await closeWebIDE(win);
-          await removeAllProjects();
+          yield closeWebIDE(win);
+          yield removeAllProjects();
           SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_runtime.html b/devtools/client/webide/test/test_runtime.html
index fb4c464fb675..79aa8125b28a 100644
--- a/devtools/client/webide/test/test_runtime.html
+++ b/devtools/client/webide/test/test_runtime.html
@@ -21,16 +21,16 @@
         let win;
 
         SimpleTest.registerCleanupFunction(() => {
-          (async function () {
+          Task.spawn(function*() {
             if (win) {
-              await closeWebIDE(win);
+              yield closeWebIDE(win);
             }
             DebuggerServer.destroy();
-            await removeAllProjects();
-          })();
+            yield removeAllProjects();
+          });
         });
 
-        (async function () {
+        Task.spawn(function*() {
           function isPlayActive() {
             return !win.document.querySelector("#cmd_play").hasAttribute("disabled");
           }
@@ -42,7 +42,7 @@
           DebuggerServer.init();
           DebuggerServer.registerAllActors();
 
-          win = await openWebIDE();
+          win = yield openWebIDE();
           let docRuntime = getRuntimeDocument(win);
           let docProject = getProjectDocument(win);
           let winProject = getProjectWindow(win);
@@ -51,9 +51,9 @@
 
           let onValidated = waitForUpdate(win, "project-validated");
           let onDetails = waitForUpdate(win, "details");
-          await winProject.projectList.importPackagedApp(packagedAppLocation);
-          await onValidated;
-          await onDetails;
+          yield winProject.projectList.importPackagedApp(packagedAppLocation);
+          yield onValidated;
+          yield onDetails;
 
           win.AppManager.runtimeList.usb.push({
             connect: function(connection) {
@@ -100,12 +100,12 @@
           items[0].click();
 
           ok(win.document.querySelector("window").className, "busy", "UI is busy");
-          await win.UI._busyPromise;
+          yield win.UI._busyPromise;
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 2, "Connected");
 
-          await waitForUpdate(win, "runtime-global-actors");
+          yield waitForUpdate(win, "runtime-global-actors");
 
           // Play button always disabled now, webapps actor removed
           ok(!isPlayActive(), "play button is disabled");
@@ -113,22 +113,22 @@
           let oldProject = win.AppManager.selectedProject;
           win.AppManager.selectedProject = null;
 
-          await nextTick();
+          yield nextTick();
 
           ok(!isPlayActive(), "play button is disabled");
           ok(!isStopActive(), "stop button is disabled");
           win.AppManager._selectedProject = oldProject;
           win.UI.updateCommands();
 
-          await nextTick();
+          yield nextTick();
 
           ok(!isPlayActive(), "play button is enabled");
           ok(!isStopActive(), "stop button is disabled");
 
           connectionsChanged = waitForConnectionChange("closed", 2);
-          await win.Cmds.disconnectRuntime();
+          yield win.Cmds.disconnectRuntime();
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 0, "Disconnected");
 
           ok(win.AppManager.selectedProject, "A project is still selected");
@@ -138,9 +138,9 @@
           connectionsChanged = waitForConnectionChange("opened", 2);
           docRuntime.querySelectorAll(".runtime-panel-item-other")[1].click();
 
-          await waitForUpdate(win, "runtime-targets");
+          yield waitForUpdate(win, "runtime-targets");
 
-          await connectionsChanged;
+          yield connectionsChanged;
           is(Object.keys(DebuggerServer._connections).length, 2, "Locally connected");
 
           ok(win.AppManager.isMainProcessDebuggable(), "Main process available");
@@ -150,13 +150,13 @@
             docProject.querySelectorAll("#project-panel-runtimeapps .panel-item")[0].click();
           });
 
-          await waitForUpdate(win, "project");
+          yield waitForUpdate(win, "project");
 
           // Toolbox opens automatically for main process / runtime apps
           ok(win.UI.toolboxPromise, "Toolbox promise exists");
-          await win.UI.toolboxPromise;
+          yield win.UI.toolboxPromise;
 
-          await win.Cmds.disconnectRuntime();
+          yield win.Cmds.disconnectRuntime();
 
           Services.prefs.setIntPref("devtools.webide.busyTimeout", 100);
 
@@ -191,7 +191,7 @@
           });
 
           SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_toolbox.html b/devtools/client/webide/test/test_toolbox.html
index e778fea0d56e..9e0611612150 100644
--- a/devtools/client/webide/test/test_toolbox.html
+++ b/devtools/client/webide/test/test_toolbox.html
@@ -21,20 +21,20 @@
         let win;
 
         SimpleTest.registerCleanupFunction(() => {
-          (async function () {
+          Task.spawn(function*() {
             if (win) {
-              await closeWebIDE(win);
+              yield closeWebIDE(win);
             }
             DebuggerServer.destroy();
-            await removeAllProjects();
-          })();
+            yield removeAllProjects();
+          });
         });
 
-        (async function () {
+        Task.spawn(function*() {
           DebuggerServer.init();
           DebuggerServer.registerAllActors();
 
-          win = await openWebIDE();
+          win = yield openWebIDE();
           let docRuntime = getRuntimeDocument(win);
           let docProject = getProjectDocument(win);
 
@@ -49,11 +49,11 @@
           docRuntime.querySelectorAll(".runtime-panel-item-other")[1].click();
 
           ok(win.document.querySelector("window").className, "busy", "UI is busy");
-          await win.UI._busyPromise;
+          yield win.UI._busyPromise;
 
           is(Object.keys(DebuggerServer._connections).length, 1, "Connected");
 
-          await waitForUpdate(win, "runtime-global-actors");
+          yield waitForUpdate(win, "runtime-global-actors");
 
           ok(win.AppManager.isMainProcessDebuggable(), "Main process available");
 
@@ -62,30 +62,30 @@
             docProject.querySelectorAll("#project-panel-runtimeapps .panel-item")[0].click();
           });
 
-          await waitForUpdate(win, "project");
+          yield waitForUpdate(win, "project");
 
           // Toolbox opens automatically for main process / runtime apps
           ok(win.UI.toolboxPromise, "Toolbox promise exists");
-          let toolbox = await win.UI.toolboxPromise;
+          let toolbox = yield win.UI.toolboxPromise;
 
-          await toolbox.destroy();
+          yield toolbox.destroy();
 
           ok(!win.UI.toolboxPromise, "Toolbox promise should be unset once toolbox.destroy()'s promise resolves");
 
           // Reopen the toolbox right after to check races and also
           // opening a toolbox more than just once against the same target
-          await win.Cmds.toggleToolbox();
+          yield win.Cmds.toggleToolbox();
 
           ok(win.UI.toolboxPromise, "Toolbox promise exists");
 
-          await win.UI.destroyToolbox();
+          yield win.UI.destroyToolbox();
 
           ok(!win.UI.toolboxPromise, "Toolbox promise is also nullified the second times");
 
-          await win.Cmds.disconnectRuntime();
+          yield win.Cmds.disconnectRuntime();
 
           SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>
diff --git a/devtools/client/webide/test/test_zoom.html b/devtools/client/webide/test/test_zoom.html
index 06861b0b4e55..a35ca652a992 100644
--- a/devtools/client/webide/test/test_zoom.html
+++ b/devtools/client/webide/test/test_zoom.html
@@ -18,8 +18,8 @@
       window.onload = function() {
         SimpleTest.waitForExplicitFinish();
 
-        (async function () {
-            let win = await openWebIDE();
+        Task.spawn(function* () {
+            let win = yield openWebIDE();
             let viewer = win.QueryInterface(Ci.nsIInterfaceRequestor)
                             .getInterface(Ci.nsIWebNavigation)
                             .QueryInterface(Ci.nsIDocShell)
@@ -52,9 +52,9 @@
             roundZoom = Math.round(10 * viewer.fullZoom) / 10;
             is(roundZoom, 1.4, "Reach max zoom");
 
-            await closeWebIDE(win);
+            yield closeWebIDE(win);
 
-            win = await openWebIDE();
+            win = yield openWebIDE();
             viewer = win.QueryInterface(Ci.nsIInterfaceRequestor)
                         .getInterface(Ci.nsIWebNavigation)
                         .QueryInterface(Ci.nsIDocShell)
@@ -67,10 +67,10 @@
 
             is(viewer.fullZoom, 1, "Zoom reset");
 
-            await closeWebIDE(win);
+            yield closeWebIDE(win);
 
             SimpleTest.finish();
-        })();
+        });
       }
     </script>
   </body>

From 2f1fb39eee160b70963981f0d7065b852af5881f Mon Sep 17 00:00:00 2001
From: Noemi Erli <nerli@mozilla.com>
Date: Tue, 13 Mar 2018 01:56:34 +0200
Subject: [PATCH 50/50] Backed out 2 changesets (bug 1444414, bug 1444357) for
 merge conflicts a=backout

Backed out changeset 6f0c06b06b6e (bug 1444414)
Backed out changeset ef01364e8730 (bug 1444357)
---
 devtools/client/shared/widgets/TreeWidget.js  | 19 -------
 .../browser_storage_cookies_delete_all.js     |  2 +-
 .../storage/test/browser_storage_delete.js    |  2 +-
 .../test/browser_storage_delete_tree.js       |  2 +-
 .../browser_storage_delete_usercontextid.js   |  2 +-
 ...browser_storage_dynamic_updates_cookies.js | 49 +++++++------------
 ...er_storage_dynamic_updates_localStorage.js | 30 +++---------
 ..._storage_dynamic_updates_sessionStorage.js | 31 +++---------
 .../test/browser_storage_indexeddb_delete.js  |  3 +-
 ...rowser_storage_indexeddb_delete_blocked.js |  4 +-
 devtools/client/storage/test/head.js          | 19 ++++---
 devtools/client/storage/ui.js                 | 22 ++++-----
 12 files changed, 63 insertions(+), 122 deletions(-)

diff --git a/devtools/client/shared/widgets/TreeWidget.js b/devtools/client/shared/widgets/TreeWidget.js
index 8678f6176989..cc927b9c2c20 100644
--- a/devtools/client/shared/widgets/TreeWidget.js
+++ b/devtools/client/shared/widgets/TreeWidget.js
@@ -272,25 +272,6 @@ TreeWidget.prototype = {
     this.setPlaceholderText("");
   },
 
-  /**
-   * Check if an item exists.
-   *
-   * @param {array} item
-   *        The array of ids leading up to the item.
-   */
-  exists: function (item) {
-    let bookmark = this.root;
-
-    for (let id of item) {
-      if (bookmark.items.has(id)) {
-        bookmark = bookmark.items.get(id);
-      } else {
-        return false;
-      }
-    }
-    return true;
-  },
-
   /**
    * Removes the specified item and all of its child items from the tree.
    *
diff --git a/devtools/client/storage/test/browser_storage_cookies_delete_all.js b/devtools/client/storage/test/browser_storage_cookies_delete_all.js
index 6fc8bc2a9b2a..b8c0418f895d 100644
--- a/devtools/client/storage/test/browser_storage_cookies_delete_all.js
+++ b/devtools/client/storage/test/browser_storage_cookies_delete_all.js
@@ -22,7 +22,7 @@ function* performDelete(store, rowName, action) {
 
   yield selectTreeItem(store);
 
-  let eventWait = gUI.once("store-objects-edit");
+  let eventWait = gUI.once("store-objects-updated");
   let cells = getRowCells(rowName, true);
 
   yield waitForContextMenu(contextMenu, cells.name, () => {
diff --git a/devtools/client/storage/test/browser_storage_delete.js b/devtools/client/storage/test/browser_storage_delete.js
index 4d02d8ac0d66..f154c6a6827c 100644
--- a/devtools/client/storage/test/browser_storage_delete.js
+++ b/devtools/client/storage/test/browser_storage_delete.js
@@ -38,7 +38,7 @@ add_task(function* () {
     let row = getRowCells(rowName);
     ok(gUI.table.items.has(rowName), `There is a row '${rowName}' in ${treeItemName}`);
 
-    let eventWait = gUI.once("store-objects-edit");
+    let eventWait = gUI.once("store-objects-updated");
 
     yield waitForContextMenu(contextMenu, row[cellToClick], () => {
       info(`Opened context menu in ${treeItemName}, row '${rowName}'`);
diff --git a/devtools/client/storage/test/browser_storage_delete_tree.js b/devtools/client/storage/test/browser_storage_delete_tree.js
index fbd56166c2b5..32fd410a0d84 100644
--- a/devtools/client/storage/test/browser_storage_delete_tree.js
+++ b/devtools/client/storage/test/browser_storage_delete_tree.js
@@ -50,7 +50,7 @@ add_task(function* () {
     yield selectTreeItem(store);
 
     let eventName = "store-objects-" +
-      (store[0] == "cookies" ? "edit" : "cleared");
+      (store[0] == "cookies" ? "updated" : "cleared");
     let eventWait = gUI.once(eventName);
 
     let selector = `[data-id='${JSON.stringify(store)}'] > .tree-widget-item`;
diff --git a/devtools/client/storage/test/browser_storage_delete_usercontextid.js b/devtools/client/storage/test/browser_storage_delete_usercontextid.js
index f690bbee6b43..c9b84771b51d 100644
--- a/devtools/client/storage/test/browser_storage_delete_usercontextid.js
+++ b/devtools/client/storage/test/browser_storage_delete_usercontextid.js
@@ -154,7 +154,7 @@ add_task(function* () {
     let row = getRowCells(rowName);
     ok(gUI.table.items.has(rowName), `There is a row '${rowName}' in ${treeItemName}`);
 
-    let eventWait = gUI.once("store-objects-edit");
+    let eventWait = gUI.once("store-objects-updated");
 
     yield waitForContextMenu(contextMenu, row[cellToClick], () => {
       info(`Opened context menu in ${treeItemName}, row '${rowName}'`);
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
index de0e51b56c63..b4ab388e8820 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_cookies.js
@@ -52,8 +52,9 @@ add_task(function* () {
   ]);
   checkCell(c1id, "value", "1.2.3.4.5.6.7");
 
-  yield addCookie("c1", '{"foo": 4,"bar":6}', "/browser");
-  yield gUI.once("store-objects-edit");
+  gWindow.addCookie("c1", '{"foo": 4,"bar":6}', "/browser");
+  yield gUI.once("sidebar-updated");
+  yield gUI.once("store-objects-updated");
 
   yield findVariableViewProperties(finalValue[0], false);
   yield findVariableViewProperties(finalValue[1], true);
@@ -70,9 +71,9 @@ add_task(function* () {
   checkCell(c1id, "value", '{"foo": 4,"bar":6}');
 
   // Add a new entry
-  yield addCookie("c3", "booyeah");
+  gWindow.addCookie("c3", "booyeah");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -90,9 +91,11 @@ add_task(function* () {
   checkCell(c3id, "value", "booyeah");
 
   // Add another
-  yield addCookie("c4", "booyeah");
+  gWindow.addCookie("c4", "booyeah");
 
-  yield gUI.once("store-objects-edit");
+  // Wait once for update and another time for value fetching
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -112,9 +115,10 @@ add_task(function* () {
   checkCell(c4id, "value", "booyeah");
 
   // Removing cookies
-  yield removeCookie("c1", "/browser");
+  gWindow.removeCookie("c1", "/browser");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("sidebar-updated");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -135,9 +139,9 @@ add_task(function* () {
   yield findVariableViewProperties([{name: "c2", value: "foobar"}]);
 
   // Keep deleting till no rows
-  yield removeCookie("c3");
+  gWindow.removeCookie("c3");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -153,9 +157,10 @@ add_task(function* () {
   // Check if next element's value is visible in sidebar
   yield findVariableViewProperties([{name: "c2", value: "foobar"}]);
 
-  yield removeCookie("c2", "/browser");
+  gWindow.removeCookie("c2", "/browser");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("sidebar-updated");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -170,9 +175,9 @@ add_task(function* () {
   // Check if next element's value is visible in sidebar
   yield findVariableViewProperties([{name: "c4", value: "booyeah"}]);
 
-  yield removeCookie("c4");
+  gWindow.removeCookie("c4");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [["cookies", "http://test1.example.org"], [ ]],
@@ -182,19 +187,3 @@ add_task(function* () {
 
   yield finishTests();
 });
-
-function* addCookie(name, value, path) {
-  yield ContentTask.spawn(gBrowser.selectedBrowser, [name, value, path],
-    ([nam, valu, pat]) => {
-      content.wrappedJSObject.addCookie(nam, valu, pat);
-    }
-  );
-}
-
-function* removeCookie(name, path) {
-  yield ContentTask.spawn(gBrowser.selectedBrowser, [name, path],
-    ([nam, pat]) => {
-      content.wrappedJSObject.removeCookie(nam, pat);
-    }
-  );
-}
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
index 074047e2c037..6980e3e55444 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_localStorage.js
@@ -20,9 +20,9 @@ add_task(function* () {
     ],
   ]);
 
-  yield removeLocalStorageItem("ls4");
+  gWindow.localStorage.removeItem("ls4");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -31,9 +31,10 @@ add_task(function* () {
     ],
   ]);
 
-  yield setLocalStorageItem("ls4", "again");
+  gWindow.localStorage.setItem("ls4", "again");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -42,9 +43,10 @@ add_task(function* () {
     ],
   ]);
   // Updating a row
-  yield setLocalStorageItem("ls2", "ls2-changed");
+  gWindow.localStorage.setItem("ls2", "ls2-changed");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
   checkCell("ls2", "value", "ls2-changed");
 
@@ -64,19 +66,3 @@ add_task(function* () {
 
   yield finishTests();
 });
-
-function* setLocalStorageItem(key, value) {
-  yield ContentTask.spawn(gBrowser.selectedBrowser, [key, value],
-    ([innerKey, innerValue]) => {
-      content.wrappedJSObject.localStorage.setItem(innerKey, innerValue);
-    }
-  );
-}
-
-function* removeLocalStorageItem(key) {
-  yield ContentTask.spawn(gBrowser.selectedBrowser, key,
-    innerKey => {
-      content.wrappedJSObject.localStorage.removeItem(innerKey);
-    }
-  );
-}
diff --git a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
index 75b0056c5ec3..bc2a2204cef9 100644
--- a/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
+++ b/devtools/client/storage/test/browser_storage_dynamic_updates_sessionStorage.js
@@ -20,9 +20,10 @@ add_task(function* () {
     ],
   ]);
 
-  yield setSessionStorageItem("ss4", "new-item");
+  gWindow.sessionStorage.setItem("ss4", "new-item");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -33,13 +34,13 @@ add_task(function* () {
 
   // deleting item
 
-  yield removeSessionStorageItem("ss3");
+  gWindow.sessionStorage.removeItem("ss3");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
 
-  yield removeSessionStorageItem("ss1");
+  gWindow.sessionStorage.removeItem("ss1");
 
-  yield gUI.once("store-objects-edit");
+  yield gUI.once("store-objects-updated");
 
   yield checkState([
     [
@@ -55,7 +56,7 @@ add_task(function* () {
   // Checking for correct value in sidebar before update
   yield findVariableViewProperties([{name: "ss2", value: "foobar"}]);
 
-  yield setSessionStorageItem("ss2", "changed=ss2");
+  gWindow.sessionStorage.setItem("ss2", "changed=ss2");
 
   yield gUI.once("sidebar-updated");
 
@@ -79,19 +80,3 @@ add_task(function* () {
 
   yield finishTests();
 });
-
-function* setSessionStorageItem(key, value) {
-  yield ContentTask.spawn(gBrowser.selectedBrowser, [key, value],
-    ([innerKey, innerValue]) => {
-      content.wrappedJSObject.sessionStorage.setItem(innerKey, innerValue);
-    }
-  );
-}
-
-function* removeSessionStorageItem(key) {
-  yield ContentTask.spawn(gBrowser.selectedBrowser, key,
-    innerKey => {
-      content.wrappedJSObject.sessionStorage.removeItem(innerKey);
-    }
-  );
-}
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_delete.js b/devtools/client/storage/test/browser_storage_indexeddb_delete.js
index 16757a474c21..b4f5db7ed63e 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_delete.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_delete.js
@@ -25,7 +25,8 @@ add_task(function* () {
   yield selectTreeItem(deletedDb);
 
   // Wait once for update and another time for value fetching
-  let eventWait = gUI.once("store-objects-updated");
+  let eventWait = gUI.once("store-objects-updated").then(
+    () => gUI.once("store-objects-updated"));
 
   let selector = `[data-id='${JSON.stringify(deletedDb)}'] > .tree-widget-item`;
   let target = gPanelWindow.document.querySelector(selector);
diff --git a/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js b/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
index 9136bc44aa6a..b4c42bf288d0 100644
--- a/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
+++ b/devtools/client/storage/test/browser_storage_indexeddb_delete_blocked.js
@@ -28,7 +28,7 @@ add_task(function* () {
     [["indexedDB", "http://test1.example.org"], ["idb (default)"]]
   ]);
 
-  let eventWait = gUI.once("store-objects-edit");
+  let eventWait = gUI.once("store-objects-updated");
 
   info("telling content to close the db");
   yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
@@ -36,7 +36,7 @@ add_task(function* () {
     yield win.closeDb();
   });
 
-  info("waiting for store edit events");
+  info("waiting for store update events");
   yield eventWait;
 
   info("test state after real delete");
diff --git a/devtools/client/storage/test/head.js b/devtools/client/storage/test/head.js
index 0e7a44969c1a..f19472cab074 100644
--- a/devtools/client/storage/test/head.js
+++ b/devtools/client/storage/test/head.js
@@ -30,7 +30,7 @@ const ALT_DOMAIN_SECURED = "https://sectest1.example.org:443/" + PATH;
 // devtools/client/storage/ui.js and devtools/server/tests/browser/head.js
 const SEPARATOR_GUID = "{9d414cc5-8319-0a04-0586-c0a6ae01670a}";
 
-var gToolbox, gPanelWindow, gUI;
+var gToolbox, gPanelWindow, gWindow, gUI;
 
 // Services.prefs.setBoolPref(DUMPEMIT_PREF, true);
 // Services.prefs.setBoolPref(DEBUGGERLOG_PREF, true);
@@ -38,7 +38,7 @@ var gToolbox, gPanelWindow, gUI;
 Services.prefs.setBoolPref(STORAGE_PREF, true);
 Services.prefs.setBoolPref(CACHES_ON_HTTP_PREF, true);
 registerCleanupFunction(() => {
-  gToolbox = gPanelWindow = gUI = null;
+  gToolbox = gPanelWindow = gWindow = gUI = null;
   Services.prefs.clearUserPref(CACHES_ON_HTTP_PREF);
   Services.prefs.clearUserPref(DEBUGGERLOG_PREF);
   Services.prefs.clearUserPref(DOM_CACHE);
@@ -57,6 +57,9 @@ registerCleanupFunction(() => {
  */
 function* openTab(url, options = {}) {
   let tab = yield addTab(url, options);
+  let content = tab.linkedBrowser.contentWindowAsCPOW;
+
+  gWindow = content.wrappedJSObject;
 
   // Setup the async storages in main window and for all its iframes
   yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
@@ -216,6 +219,8 @@ function forceCollections() {
  * Cleans up and finishes the test
  */
 function* finishTests() {
+  // Bug 1233497 makes it so that we can no longer yield CPOWs from Tasks.
+  // We work around this by calling clear() via a ContentTask instead.
   while (gBrowser.tabs.length > 1) {
     yield ContentTask.spawn(gBrowser.selectedBrowser, null, function* () {
       /**
@@ -507,17 +512,11 @@ function matchVariablesViewProperty(prop, rule) {
  *        The array id of the item in the tree
  */
 function* selectTreeItem(ids) {
+  /* If this item is already selected, return */
   if (gUI.tree.isSelected(ids)) {
-    info(`"${ids}" is already selected, returning.`);
-    return;
-  }
-  if (!gUI.tree.exists(ids)) {
-    info(`"${ids}" does not exist, returning.`);
     return;
   }
 
-  // The item exists but is not selected... select it.
-  info(`Selecting "${ids}".`);
   let updated = gUI.once("store-objects-updated");
   gUI.tree.selectedItem = ids;
   yield updated;
@@ -991,7 +990,7 @@ function* performAdd(store) {
   }
 
   let eventEdit = gUI.table.once("row-edit");
-  let eventWait = gUI.once("store-objects-edit");
+  let eventWait = gUI.once("store-objects-updated");
 
   menuAdd.click();
 
diff --git a/devtools/client/storage/ui.js b/devtools/client/storage/ui.js
index 109a14e17b47..51911630948e 100644
--- a/devtools/client/storage/ui.js
+++ b/devtools/client/storage/ui.js
@@ -141,8 +141,8 @@ class StorageUI {
       console.error(e);
     });
 
-    this.onEdit = this.onEdit.bind(this);
-    this.front.on("stores-update", this.onEdit);
+    this.onUpdate = this.onUpdate.bind(this);
+    this.front.on("stores-update", this.onUpdate);
     this.onCleared = this.onCleared.bind(this);
     this.front.on("stores-cleared", this.onCleared);
 
@@ -216,7 +216,7 @@ class StorageUI {
     this.table.off(TableWidget.EVENTS.CELL_EDIT, this.editItem);
     this.table.destroy();
 
-    this.front.off("stores-update", this.onEdit);
+    this.front.off("stores-update", this.onUpdate);
     this.front.off("stores-cleared", this.onCleared);
     this._panelDoc.removeEventListener("keypress", this.handleKeypress);
     this.searchBox.removeEventListener("input", this.filterItems);
@@ -401,7 +401,7 @@ class StorageUI {
    *        of the changed store objects. This array is empty for deleted object
    *        if the host was completely removed.
    */
-  async onEdit({ changed, added, deleted }) {
+  async onUpdate({ changed, added, deleted }) {
     if (added) {
       await this.handleAddedItems(added);
     }
@@ -421,14 +421,14 @@ class StorageUI {
     }
 
     if (added || deleted || changed) {
-      this.emit("store-objects-edit");
+      this.emit("store-objects-updated");
     }
   }
 
   /**
-   * Handle added items received by onEdit
+   * Handle added items received by onUpdate
    *
-   * @param {object} See onEdit docs
+   * @param {object} See onUpdate docs
    */
   async handleAddedItems(added) {
     for (let type in added) {
@@ -460,9 +460,9 @@ class StorageUI {
   }
 
   /**
-   * Handle deleted items received by onEdit
+   * Handle deleted items received by onUpdate
    *
-   * @param {object} See onEdit docs
+   * @param {object} See onUpdate docs
    */
   async handleDeletedItems(deleted) {
     for (let type in deleted) {
@@ -512,9 +512,9 @@ class StorageUI {
   }
 
   /**
-   * Handle changed items received by onEdit
+   * Handle changed items received by onUpdate
    *
-   * @param {object} See onEdit docs
+   * @param {object} See onUpdate docs
    */
   async handleChangedItems(changed) {
     let [type, host, db, objectStore] = this.tree.selectedItem;