merge mozilla-central to mozilla-inbound. r=merge a=merge

browser/config/mozconfigs/linux64/noopt-debug

@@ -1,3 +1,5 @@
+MOZ_AUTOMATION_BUILD_SYMBOLS=0
+
 # Developers often build with these options for a better debugging experience.
 . "$topsrcdir/browser/config/mozconfigs/linux64/debug"
 

browser/config/mozconfigs/macosx64/cross-noopt-debug

@@ -1,3 +1,5 @@
+MOZ_AUTOMATION_BUILD_SYMBOLS=0
+
 # Developers often build with these options for a better debugging experience.
 . "$topsrcdir/browser/config/mozconfigs/macosx64/debug"
 

browser/config/mozconfigs/win32/noopt-debug

@@ -1,3 +1,5 @@
+MOZ_AUTOMATION_BUILD_SYMBOLS=0
+
 # Developers often build with these options for a better debugging experience.
 . "$topsrcdir/browser/config/mozconfigs/win32/debug"
 

browser/config/mozconfigs/win64/noopt-debug

@@ -1,3 +1,5 @@
+MOZ_AUTOMATION_BUILD_SYMBOLS=0
+
 # Developers often build with these options for a better debugging experience.
 . "$topsrcdir/browser/config/mozconfigs/win64/debug"
 

browser/extensions/formautofill/FormAutofillContent.jsm

@@ -440,54 +440,42 @@ var FormAutofillContent = {
     return formDetails.map(record => record.fieldName);
   },
 
-  identifyAutofillFields(doc) {
-    this.log.debug("identifyAutofillFields:", "" + doc.location);
+  identifyAutofillFields(element) {
+    this.log.debug("identifyAutofillFields:", "" + element.ownerDocument.location);
 
     if (!this.savedFieldNames) {
       this.log.debug("identifyAutofillFields: savedFieldNames are not known yet");
       Services.cpmm.sendAsyncMessage("FormAutofill:InitStorage");
     }
 
-    let forms = [];
-
-    // Collects root forms from inputs.
-    for (let field of FormAutofillUtils.autofillFieldSelector(doc)) {
-      if (!FormAutofillUtils.isFieldEligibleForAutofill(field)) {
-        continue;
-      }
-
-      // For now skip consider fields in forms we've already seen before even
-      // if the specific field wasn't seen before. Ideally whether the field is
-      // already in the handler's form details would be considered.
-      if (this.getFormHandler(field)) {
-        continue;
-      }
-
-      let formLike = FormLikeFactory.createFromField(field);
-      if (!forms.some(form => form.rootElement === formLike.rootElement)) {
-        forms.push(formLike);
-      }
+    if (!FormAutofillUtils.isFieldEligibleForAutofill(element)) {
+      this.log.debug("Not an eligible field.");
+      return;
     }
 
-    this.log.debug("Found", forms.length, "forms");
+    let formHandler = this.getFormHandler(element);
+    if (!formHandler) {
+      let formLike = FormLikeFactory.createFromField(element);
+      formHandler = new FormAutofillHandler(formLike);
+    } else if (!formHandler.isFormChangedSinceLastCollection) {
+      this.log.debug("No control is removed or inserted since last collection.");
+      return;
+    }
 
-    // Collects the fields that can be autofilled from each form and marks them
-    // as autofill fields if the amount is above the threshold.
-    forms.forEach(form => {
-      let formHandler = new FormAutofillHandler(form);
-      formHandler.collectFormFields();
-      if (formHandler.fieldDetails.length < AUTOFILL_FIELDS_THRESHOLD) {
-        this.log.debug("Ignoring form since it has only", formHandler.fieldDetails.length,
-                       "field(s)");
-        return;
-      }
+    formHandler.collectFormFields();
 
-      this._formsDetails.set(form.rootElement, formHandler);
-      this.log.debug("Adding form handler to _formsDetails:", formHandler);
-      formHandler.fieldDetails.forEach(detail =>
-        this._markAsAutofillField(detail.elementWeakRef.get())
-      );
-    });
+    this._formsDetails.set(formHandler.form.rootElement, formHandler);
+    this.log.debug("Adding form handler to _formsDetails:", formHandler);
+
+    if (formHandler.fieldDetails.length < AUTOFILL_FIELDS_THRESHOLD) {
+      this.log.debug("Ignoring form since it has only", formHandler.fieldDetails.length,
+                     "field(s)");
+      return;
+    }
+
+    formHandler.fieldDetails.forEach(detail =>
+      this._markAsAutofillField(detail.elementWeakRef.get())
+    );
   },
 
   _markAsAutofillField(field) {

browser/extensions/formautofill/FormAutofillHandler.jsm

@@ -39,6 +39,8 @@ FormAutofillHandler.prototype = {
    */
   form: null,
 
+  _formFieldCount: 0,
+
   /**
    * Array of collected data about relevant form fields.  Each item is an object
    * storing the identifying details of the field and a reference to the
@@ -76,10 +78,19 @@ FormAutofillHandler.prototype = {
     PREVIEW: "-moz-autofill-preview",
   },
 
+  get isFormChangedSinceLastCollection() {
+    // When the number of form controls is the same with last collection, it
+    // can be recognized as there is no element changed. However, we should
+    // improve the function to detect the element changes. e.g. a tel field
+    // is changed from type="hidden" to type="tel".
+    return this._formFieldCount != this.form.elements.length;
+  },
+
   /**
    * Set fieldDetails from the form about fields that can be autofilled.
    */
   collectFormFields() {
+    this._formFieldCount = this.form.elements.length;
     let fieldDetails = FormAutofillHeuristics.getFormInfo(this.form);
     this.fieldDetails = fieldDetails ? fieldDetails : [];
     log.debug("Collected details on", this.fieldDetails.length, "fields");
@@ -174,10 +185,11 @@ FormAutofillHandler.prototype = {
         hasFilledFields |= (fieldDetail.state == "AUTO_FILLED");
       }
 
-      // Unregister listeners once no field is in AUTO_FILLED state.
+      // Unregister listeners and clear guid once no field is in AUTO_FILLED state.
       if (!hasFilledFields) {
         this.form.rootElement.removeEventListener("input", onChangeHandler);
         this.form.rootElement.removeEventListener("reset", onChangeHandler);
+        this.filledProfileGUID = null;
       }
     };
 

browser/extensions/formautofill/content/FormAutofillFrameScript.js

@@ -48,7 +48,7 @@ var FormAutofillFrameScript = {
         }
 
         let doIdentifyAutofillFields =
-          () => setTimeout(() => FormAutofillContent.identifyAutofillFields(doc));
+          () => setTimeout(() => FormAutofillContent.identifyAutofillFields(element));
 
         if (doc.readyState === "loading") {
           doc.addEventListener("DOMContentLoaded", doIdentifyAutofillFields, {once: true});

browser/extensions/formautofill/test/mochitest/test_basic_autocomplete_form.html

@@ -164,6 +164,18 @@ add_task(async function check_fallback_after_form_autofill() {
   checkMenuEntries(["1-234-567-890"]);
 });
 
+// Resume form autofill once all the autofilled fileds are changed.
+add_task(async function check_form_autofill_resume() {
+  document.querySelector("#tel").blur();
+  document.querySelector("#form1").reset();
+  await setInput("#tel", "");
+  doKey("down");
+  await expectPopup();
+  checkMenuEntries(MOCK_STORAGE.map(address =>
+    JSON.stringify({primary: address.tel, secondary: address["street-address"]})
+  ));
+});
+
 registerPopupShownListener(popupShownListener);
 
 </script>

browser/extensions/formautofill/test/unit/test_getFormInputDetails.js

@@ -84,10 +84,10 @@ TESTCASES.forEach(testcase => {
 
     let doc = MockDocument.createTestDocument(
               "http://localhost:8080/test/", testcase.document);
-    FormAutofillContent.identifyAutofillFields(doc);
 
     for (let i in testcase.targetInput) {
       let input = doc.getElementById(testcase.targetInput[i]);
+      FormAutofillContent.identifyAutofillFields(input);
 
       // Put the input element reference to `element` to make sure the result of
       // `getInputDetails` contains the same input element.

browser/extensions/formautofill/test/unit/test_markAsAutofillField.js

@@ -17,6 +17,7 @@ const TESTCASES = [
                  <input id="without-autocomplete-1">
                  <input id="without-autocomplete-2">
                </form>`,
+    targetElementId: "given-name",
     expectedResult: [
       "given-name",
       "additional-name",
@@ -36,6 +37,7 @@ const TESTCASES = [
                  <input id="without-autocomplete-1">
                  <input id="without-autocomplete-2">
                </form>`,
+    targetElementId: "street-addr",
     expectedResult: [],
   },
   {
@@ -47,6 +49,7 @@ const TESTCASES = [
                <input id="tel" autocomplete="tel">
                <input id="without-autocomplete-1">
                <input id="without-autocomplete-2">`,
+    targetElementId: "street-addr",
     expectedResult: [
       "street-addr",
       "city",
@@ -70,7 +73,8 @@ TESTCASES.forEach(testcase => {
 
     let doc = MockDocument.createTestDocument(
       "http://localhost:8080/test/", testcase.document);
-    FormAutofillContent.identifyAutofillFields(doc);
+    let element = doc.getElementById(testcase.targetElementId);
+    FormAutofillContent.identifyAutofillFields(element);
 
     Assert.deepEqual(markedFieldId, testcase.expectedResult,
       "Check the fields were marked correctly.");

browser/extensions/formautofill/test/unit/test_onFormSubmitted.js

@@ -11,6 +11,7 @@ const MOCK_DOC = MockDocument.createTestDocument("http://localhost:8080/test/",
                       <input id="tel" autocomplete="tel">
                       <input id="submit" type="submit">
                     </form>`);
+const TARGET_ELEMENT_ID = "street-addr";
 
 const TESTCASES = [
   {
@@ -110,7 +111,8 @@ TESTCASES.forEach(testcase => {
     }
     sinon.stub(FormAutofillContent, "_onFormSubmit");
 
-    FormAutofillContent.identifyAutofillFields(MOCK_DOC);
+    let element = MOCK_DOC.getElementById(TARGET_ELEMENT_ID);
+    FormAutofillContent.identifyAutofillFields(element);
     FormAutofillContent.notify(form);
 
     do_check_eq(FormAutofillContent._onFormSubmit.called,

browser/extensions/onboarding/content/onboarding-tour-agent.js

@@ -9,6 +9,12 @@
 document.getElementById("onboarding-overlay-dialog")
                         .addEventListener("click", evt => {
   switch (evt.target.id) {
+    case "onboarding-tour-addons-button":
+      Mozilla.UITour.showHighlight("addons");
+      break;
+    case "onboarding-tour-customize-button":
+      Mozilla.UITour.showHighlight("customize");
+      break;
     case "onboarding-tour-private-browsing-button":
       Mozilla.UITour.showHighlight("privateWindow");
       break;

browser/extensions/onboarding/content/onboarding.css

@@ -225,3 +225,30 @@
 #onboarding-tour-private-browsing:hover {
   background-image: url("img/icons_private-colored.svg");
 }
+
+#onboarding-tour-addons {
+  background-image: url("img/icons_addons.svg");
+}
+
+#onboarding-tour-addons.onboarding-active,
+#onboarding-tour-addons:hover {
+  background-image: url("img/icons_addons-colored.svg");
+}
+
+#onboarding-tour-customize {
+  background-image: url("img/icons_customize.svg");
+}
+
+#onboarding-tour-customize.onboarding-active,
+#onboarding-tour-customize:hover {
+  background-image: url("img/icons_customize-colored.svg");
+}
+
+#onboarding-tour-default-browser {
+  background-image: url("img/icons_default.svg");
+}
+
+#onboarding-tour-default-browser.onboarding-active,
+#onboarding-tour-default-browser:hover {
+  background-image: url("img/icons_default-colored.svg");
+}

browser/extensions/onboarding/content/onboarding.js

@@ -33,8 +33,6 @@ const BRAND_SHORT_NAME = Services.strings
  *   // Add no-button css class in the div if this tour does not need a button.
  *   // The overlay layout will responsively position and distribute space for these 3 sections based on viewport size
  *   getPage() {},
- *   isCompleted() {},
- *   setCompleted() {},
  * },
  **/
 var onboardingTours = [
@@ -57,13 +55,45 @@ var onboardingTours = [
       `;
       return div;
     },
-    isCompleted() {
-      // TODO: determine completion by looking up preferences.
-      return false;
+  },
+  {
+    id: "onboarding-tour-addons",
+    tourNameId: "onboarding.tour-addons",
+    getPage(win) {
+      let div = win.document.createElement("div");
+      div.innerHTML = `
+        <section class="onboarding-tour-description">
+          <h1 data-l10n-id="onboarding.tour-addons.title"></h1>
+          <p data-l10n-id="onboarding.tour-addons.description"></p>
+        </section>
+        <section class="onboarding-tour-content">
+          <img src="resource://onboarding/img/figure_addons.svg" />
+        </section>
+        <aside class="onboarding-tour-button">
+          <button id="onboarding-tour-addons-button" data-l10n-id="onboarding.tour-addons.button"></button>
+        </aside>
+      `;
+      return div;
     },
-    setCompleted() {
-      // TODO: set completion to preferences.
-      return true;
+  },
+  {
+    id: "onboarding-tour-customize",
+    tourNameId: "onboarding.tour-customize",
+    getPage(win) {
+      let div = win.document.createElement("div");
+      div.innerHTML = `
+        <section class="onboarding-tour-description">
+          <h1 data-l10n-id="onboarding.tour-customize.title"></h1>
+          <p data-l10n-id="onboarding.tour-customize.description"></p>
+        </section>
+        <section class="onboarding-tour-content">
+          <img src="resource://onboarding/img/figure_customize.svg" />
+        </section>
+        <aside class="onboarding-tour-button">
+          <button id="onboarding-tour-customize-button" data-l10n-id="onboarding.tour-customize.button"></button>
+        </aside>
+      `;
+      return div;
     },
   },
   {
@@ -85,13 +115,22 @@ var onboardingTours = [
       `;
       return div;
     },
-    isCompleted() {
-      // TODO: determine completion by looking up preferences.
-      return false;
-    },
-    setCompleted() {
-      // TODO: set completion to preferences.
-      return true;
+  },
+  {
+    id: "onboarding-tour-default-browser",
+    tourNameId: "onboarding.tour-default-browser",
+    getPage(win) {
+      let div = win.document.createElement("div");
+      div.innerHTML = `
+        <section class="onboarding-tour-description">
+          <h1 data-l10n-id="onboarding.tour-default-browser.title"></h1>
+          <p data-l10n-id="onboarding.tour-default-browser.description"></p>
+        </section>
+        <section class="onboarding-tour-content">
+          <img src="resource://onboarding/img/figure_default.svg" />
+        </section>
+      `;
+      return div;
     },
   },
 ];

browser/extensions/onboarding/locales/en-US/onboarding.properties

@@ -1,8 +1,7 @@
 # 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/.
-# LOCALIZATION NOTE(onboarding.overlay-title): This string will be used in the
-# overlay title. %S is brandShortName.
+# LOCALIZATION NOTE(onboarding.tour-title): This string will be used in the overlay title. %S is brandShortName
 onboarding.overlay-title=Getting started with %S
 onboarding.tour-search=One-Click Search
 onboarding.tour-search.title=Find the needle or the haystack.
@@ -17,8 +16,30 @@ onboarding.tour-search.button=Open One-Click Search
 onboarding.tour-private-browsing=Private Browsing
 onboarding.tour-private-browsing.title=A little privacy goes a long way.
 
-# LOCALIZATION NOTE(onboarding.tour-private-browsing.description): %S is
-# brandShortName.
+# LOCALIZATION NOTE(onboarding.tour-private-browsing.description): %S is brandShortName.
 onboarding.tour-private-browsing.description=Browse the internet without saving your searches or the sites you visited. When your session ends, the cookies disappear from %S like they were never there.
 onboarding.tour-private-browsing.button=Show Private Browsing in Menu
 onboarding.hidden-checkbox-label=Hide the tour
+onboarding.tour-addons=Add-ons
+onboarding.tour-addons.title=Add more functionality.
+
+# LOCALIZATION NOTE(onboarding.tour-addons.description): This string will be used in the add-on tour description. %1$S is brandShortName
+onboarding.tour-addons.description=Add-ons expand %1$S’s built-in features, so %1$S works the way you do. Compare prices, check the weather or express your personality with a custom theme.
+onboarding.tour-addons.button=Show Add-ons in Menu
+onboarding.tour-customize=Customize
+onboarding.tour-customize.title=Do things your way.
+
+# LOCALIZATION NOTE(onboarding.tour-customize.description): This string will be used in the customize tour description. %S is brandShortName
+onboarding.tour-customize.description=Drag, drop, and reorder %S’s toolbar and menu to fit your needs. You can even select a compact theme to give websites more room.
+onboarding.tour-customize.button=Show Customize in Menu
+onboarding.tour-default-browser=Default Browser
+onboarding.tour-default-browser.title=We’re there for you.
+
+# LOCALIZATION NOTE(onboarding.tour-default-browser.description): This string will be used in the default browser tour description. %1$S is brandShortName
+onboarding.tour-default-browser.description=Love %1$S? Set it as your default browser. Then when you open a link from another application, %1$S has you covered.
+
+# LOCALIZATION NOTE(onboarding.tour-default-browser.button): Label for a button to open the OS default browser settings where it's not possible to set the default browser directly. (OSX, Linux, Windows 8 and higher)
+onboarding.tour-default-browser.button=Open Default Browser Settings
+
+# LOCALIZATION NOTE(onboarding.tour-default-browser.win7.button): Label for a button to directly set the default browser (Windows 7). %S is brandShortName
+onboarding.tour-default-browser.win7.button=Make %S Your Default Browser

build/moz.configure/toolchain.configure

@@ -873,6 +873,20 @@ host_cxx_compiler = compiler('C++', host, c_compiler=host_c_compiler,
 non_msvc_compiler = depends(c_compiler)(lambda info: info.type != 'msvc')
 building_with_gcc = depends(c_compiler)(lambda info: info.type == 'gcc')
 
+@depends(c_compiler)
+def msvs_version(info):
+    # clang-cl emulates the same version scheme as cl. And MSVS_VERSION needs to
+    # be set for GYP on Windows.
+    if info.type in ('clang-cl', 'msvc'):
+        if info.version >= '19.10':
+            return '2017'
+        elif info.version >= '19.00':
+            return '2015'
+
+    return ''
+
+set_config('MSVS_VERSION', msvs_version)
+
 include('compile-checks.configure')
 
 @depends(have_64_bit,

dom/animation/AnimValuesStyleRule.cpp

@@ -6,7 +6,7 @@
 
 #include "AnimValuesStyleRule.h"
 #include "nsRuleData.h"
-#include "nsStyleContext.h"
+#include "mozilla/GeckoStyleContext.h"
 
 namespace mozilla {
 
@@ -15,7 +15,7 @@ NS_IMPL_ISUPPORTS(AnimValuesStyleRule, nsIStyleRule)
 void
 AnimValuesStyleRule::MapRuleInfoInto(nsRuleData* aRuleData)
 {
-  nsStyleContext *contextParent = aRuleData->mStyleContext->GetParent();
+  GeckoStyleContext *contextParent = aRuleData->mStyleContext->GetParent();
   if (contextParent && contextParent->HasPseudoElementData()) {
     // Don't apply transitions or animations to things inside of
     // pseudo-elements.

dom/animation/EffectCompositor.cpp

@@ -15,6 +15,7 @@
 #include "mozilla/AnimationUtils.h"
 #include "mozilla/AutoRestore.h"
 #include "mozilla/EffectSet.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/LayerAnimationInfo.h"
 #include "mozilla/RestyleManager.h"
 #include "mozilla/RestyleManagerInlines.h"
@@ -33,6 +34,7 @@
 #include "nsLayoutUtils.h"
 #include "nsRuleNode.h" // For nsRuleNode::ComputePropertiesOverridingAnimation
 #include "nsRuleProcessorData.h" // For ElementRuleProcessorData etc.
+#include "nsStyleContextInlines.h"
 #include "nsTArray.h"
 #include <bitset>
 #include <initializer_list>
@@ -168,7 +170,7 @@ FindAnimationsForCompositor(const nsIFrame* aFrame,
     EffectCompositor::GetAnimationElementAndPseudoForFrame(aFrame);
   if (pseudoElement) {
     StyleBackendType backend =
-      aFrame->StyleContext()->StyleSource().IsServoComputedValues()
+      aFrame->StyleContext()->IsServo()
       ? StyleBackendType::Servo
       : StyleBackendType::Gecko;
     EffectCompositor::MaybeUpdateCascadeResults(backend,
@@ -801,7 +803,7 @@ EffectCompositor::GetOverriddenProperties(StyleBackendType aBackendType,
       break;
     case StyleBackendType::Gecko:
       nsRuleNode::ComputePropertiesOverridingAnimation(propertiesToTrack,
-                                                       aStyleContext,
+                                                       aStyleContext->AsGecko(),
                                                        result);
       break;
 

dom/animation/KeyframeEffectReadOnly.cpp

@@ -15,6 +15,7 @@
 #include "mozilla/AnimationUtils.h"
 #include "mozilla/AutoRestore.h"
 #include "mozilla/EffectSet.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/FloatingPoint.h" // For IsFinite
 #include "mozilla/LookAndFeel.h" // For LookAndFeel::GetInt
 #include "mozilla/KeyframeUtils.h"
@@ -28,6 +29,7 @@
 #include "nsCSSPseudoElements.h" // For CSSPseudoElementType
 #include "nsIPresShell.h"
 #include "nsIScriptError.h"
+#include "nsStyleContextInlines.h"
 
 namespace mozilla {
 
@@ -300,7 +302,7 @@ KeyframeEffectReadOnly::UpdateProperties(nsStyleContext* aStyleContext)
   }
 
   const ServoComputedValues* currentStyle =
-    aStyleContext->StyleSource().AsServoComputedValues();
+    aStyleContext->ComputedValues();
 
   DoUpdateProperties(currentStyle);
 }
@@ -1643,7 +1645,7 @@ CreateStyleContextForAnimationValue(nsCSSPropertyID aProperty,
 
   // We need to call StyleData to generate cached data for the style context.
   // Otherwise CalcStyleDifference returns no meaningful result.
-  styleContext->StyleData(nsCSSProps::kSIDTable[aProperty]);
+  styleContext->AsGecko()->StyleData(nsCSSProps::kSIDTable[aProperty]);
 
   return styleContext.forget();
 }

dom/base/nsDocument.cpp

@@ -6051,32 +6051,53 @@ nsDocument::IsWebComponentsEnabled(JSContext* aCx, JSObject* aObject)
 {
   JS::Rooted<JSObject*> obj(aCx, aObject);
 
-  if (nsContentUtils::IsWebComponentsEnabled()) {
-    return true;
-  }
-
-  // Check for the webcomponents permission. See Bug 1181555.
   JSAutoCompartment ac(aCx, obj);
   JS::Rooted<JSObject*> global(aCx, JS_GetGlobalForObject(aCx, obj));
   nsCOMPtr<nsPIDOMWindowInner> window =
     do_QueryInterface(nsJSUtils::GetStaticScriptGlobal(global));
 
-  return IsWebComponentsEnabled(window);
+  bool enabled =
+    nsContentUtils::IsWebComponentsEnabled() ||
+    // Check for the webcomponents permission. See Bug 1181555.
+    IsWebComponentsEnabled(window);
+
+  if (!enabled) {
+    return false;
+  }
+
+  nsIDocument* doc = window ? window->GetExtantDoc() : nullptr;
+  if (doc && doc->IsStyledByServo()) {
+    NS_WARNING("stylo: Web Components not supported yet");
+    return false;
+  }
+
+  return true;
 }
 
 bool
 nsDocument::IsWebComponentsEnabled(dom::NodeInfo* aNodeInfo)
 {
-  if (nsContentUtils::IsWebComponentsEnabled()) {
-    return true;
+  nsIDocument* doc = aNodeInfo->GetDocument();
+
+  bool enabled = nsContentUtils::IsWebComponentsEnabled();
+  if (!enabled) {
+    // Use GetScopeObject() here so that data documents work the same way as the
+    // main document they're associated with.
+    nsCOMPtr<nsPIDOMWindowInner> window =
+      do_QueryInterface(doc->GetScopeObject());
+    enabled = IsWebComponentsEnabled(window);
   }
 
-  nsIDocument* doc = aNodeInfo->GetDocument();
-  // Use GetScopeObject() here so that data documents work the same way as the
-  // main document they're associated with.
-  nsCOMPtr<nsPIDOMWindowInner> window =
-    do_QueryInterface(doc->GetScopeObject());
-  return IsWebComponentsEnabled(window);
+  if (!enabled) {
+    return false;
+  }
+
+  if (doc->IsStyledByServo()) {
+    NS_WARNING("stylo: Web Components not supported yet");
+    return false;
+  }
+
+  return true;
 }
 
 bool

dom/base/nsDocument.h

@@ -1395,6 +1395,9 @@ private:
   void UpdatePossiblyStaleDocumentState();
   static bool CustomElementConstructor(JSContext* aCx, unsigned aArgc, JS::Value* aVp);
 
+  // Check whether web components are enabled for the given window.
+  static bool IsWebComponentsEnabled(nsPIDOMWindowInner* aWindow);
+
 public:
   virtual already_AddRefed<mozilla::dom::CustomElementRegistry>
     GetCustomElementRegistry() override;
@@ -1404,8 +1407,6 @@ public:
   // Check whether web components are enabled for the global of the document
   // this nodeinfo comes from.
   static bool IsWebComponentsEnabled(mozilla::dom::NodeInfo* aNodeInfo);
-  // Check whether web components are enabled for the given window.
-  static bool IsWebComponentsEnabled(nsPIDOMWindowInner* aWindow);
 
   RefPtr<mozilla::EventListenerManager> mListenerManager;
   RefPtr<mozilla::dom::StyleSheetList> mDOMStyleSheets;

dom/media/FileBlockCache.cpp

@@ -33,7 +33,7 @@ CloseFD(PRFileDesc* aFD)
 void
 FileBlockCache::SetCacheFile(PRFileDesc* aFD)
 {
-  LOG("SetFD(aFD=%p) mIsOpen=%d", aFD, mIsOpen);
+  LOG("SetFD(aFD=%p) mThread=%p", aFD, mThread.get());
 
   if (!aFD) {
     // Failed to get a temporary file. Shutdown.
@@ -46,13 +46,17 @@ FileBlockCache::SetCacheFile(PRFileDesc* aFD)
   }
   {
     MutexAutoLock lock(mDataMutex);
-    if (mIsOpen) {
+    if (mThread) {
       // Still open, complete the initialization.
       mInitialized = true;
       if (mIsWriteScheduled) {
         // A write was scheduled while waiting for FD. We need to run/dispatch a
         // task to service the request.
-        mThread->Dispatch(this, NS_DISPATCH_NORMAL);
+        nsCOMPtr<nsIRunnable> event = mozilla::NewRunnableMethod(
+          "FileBlockCache::SetCacheFile -> PerformBlockIOs",
+          this,
+          &FileBlockCache::PerformBlockIOs);
+        mThread->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
       }
       return;
     }
@@ -69,9 +73,18 @@ FileBlockCache::SetCacheFile(PRFileDesc* aFD)
 nsresult
 FileBlockCache::Init()
 {
+  MutexAutoLock mon(mDataMutex);
+  if (mThread) {
+    LOG("Init() again");
+    // Just discard pending changes, assume MediaCache won't read from
+    // blocks it hasn't written to.
+    mChangeIndexList.clear();
+    mBlockChanges.Clear();
+    return NS_OK;
+  }
+
   LOG("Init()");
 
-  MutexAutoLock mon(mDataMutex);
   nsresult rv = NS_NewNamedThread("FileBlockCache",
                                   getter_AddRefs(mThread),
                                   nullptr,
@@ -79,7 +92,6 @@ FileBlockCache::Init()
   if (NS_FAILED(rv)) {
     return rv;
   }
-  mIsOpen = true;
 
   if (XRE_IsParentProcess()) {
     RefPtr<FileBlockCache> self = this;
@@ -107,32 +119,28 @@ FileBlockCache::Init()
 }
 
 FileBlockCache::FileBlockCache()
-  : mFileMutex("MediaCache.Writer.IO.Mutex"),
-    mFD(nullptr),
-    mFDCurrentPos(0),
-    mDataMutex("MediaCache.Writer.Data.Mutex"),
-    mIsWriteScheduled(false),
-    mIsReading(false),
-    mIsOpen(false)
+  : mFileMutex("MediaCache.Writer.IO.Mutex")
+  , mFD(nullptr)
+  , mFDCurrentPos(0)
+  , mDataMutex("MediaCache.Writer.Data.Mutex")
+  , mIsWriteScheduled(false)
+  , mIsReading(false)
 {
 }
 
 FileBlockCache::~FileBlockCache()
 {
-  NS_ASSERTION(!mIsOpen, "Should Close() FileBlockCache before destroying");
+  Close();
 }
 
-void FileBlockCache::Close()
+void
+FileBlockCache::Close()
 {
   LOG("Close()");
 
   nsCOMPtr<nsIThread> thread;
   {
     MutexAutoLock mon(mDataMutex);
-    if (!mIsOpen) {
-      return;
-    }
-    mIsOpen = false;
     if (!mThread) {
       return;
     }
@@ -179,8 +187,9 @@ FileBlockCache::WriteBlock(uint32_t aBlockIndex,
 {
   MutexAutoLock mon(mDataMutex);
 
-  if (!mIsOpen)
+  if (!mThread) {
     return NS_ERROR_FAILURE;
+  }
 
   // Check if we've already got a pending write scheduled for this block.
   mBlockChanges.EnsureLengthAtLeast(aBlockIndex + 1);
@@ -206,7 +215,7 @@ FileBlockCache::WriteBlock(uint32_t aBlockIndex,
 void FileBlockCache::EnsureWriteScheduled()
 {
   mDataMutex.AssertCurrentThreadOwns();
-  MOZ_ASSERT(mIsOpen);
+  MOZ_ASSERT(mThread);
 
   if (mIsWriteScheduled || mIsReading) {
     return;
@@ -217,7 +226,11 @@ void FileBlockCache::EnsureWriteScheduled()
     // the write will be scheduled.
     return;
   }
-  mThread->Dispatch(this, NS_DISPATCH_NORMAL);
+  nsCOMPtr<nsIRunnable> event = mozilla::NewRunnableMethod(
+    "FileBlockCache::EnsureWriteScheduled -> PerformBlockIOs",
+    this,
+    &FileBlockCache::PerformBlockIOs);
+  mThread->Dispatch(event.forget(), NS_DISPATCH_NORMAL);
 }
 
 nsresult FileBlockCache::Seek(int64_t aOffset)
@@ -295,26 +308,26 @@ nsresult FileBlockCache::MoveBlockInFile(int32_t aSourceBlockIndex,
   return WriteBlockToFile(aDestBlockIndex, buf);
 }
 
-nsresult FileBlockCache::Run()
+void
+FileBlockCache::PerformBlockIOs()
 {
   NS_ASSERTION(!NS_IsMainThread(), "Don't call on main thread");
   MutexAutoLock mon(mDataMutex);
-  NS_ASSERTION(!mChangeIndexList.empty(), "Only dispatch when there's work to do");
   NS_ASSERTION(mIsWriteScheduled, "Should report write running or scheduled.");
 
-  LOG("Run() mFD=%p mIsOpen=%d", mFD, mIsOpen);
+  LOG("Run() mFD=%p mThread=%p", mFD, mThread.get());
 
   while (!mChangeIndexList.empty()) {
-    if (!mIsOpen) {
+    if (!mThread) {
       // We've been closed, abort, discarding unwritten changes.
       mIsWriteScheduled = false;
-      return NS_ERROR_FAILURE;
+      return;
     }
 
     if (mIsReading) {
       // We're trying to read; postpone all writes. (Reader will resume writes.)
       mIsWriteScheduled = false;
-      return NS_OK;
+      return;
     }
 
     // Process each pending change. We pop the index out of the change
@@ -339,7 +352,7 @@ nsresult FileBlockCache::Run()
       if (!mFD) {
         // We may be here if mFD has been reset because we're closing, so we
         // don't care anymore about writes.
-        return NS_OK;
+        return;
       }
       if (change->IsWrite()) {
         WriteBlockToFile(blockIndex, change->mData.get());
@@ -357,8 +370,6 @@ nsresult FileBlockCache::Run()
   }
 
   mIsWriteScheduled = false;
-
-  return NS_OK;
 }
 
 nsresult FileBlockCache::Read(int64_t aOffset,
@@ -368,8 +379,9 @@ nsresult FileBlockCache::Read(int64_t aOffset,
 {
   MutexAutoLock mon(mDataMutex);
 
-  if (!mIsOpen || (aOffset / BLOCK_SIZE) > INT32_MAX)
+  if (!mThread || (aOffset / BLOCK_SIZE) > INT32_MAX) {
     return NS_ERROR_FAILURE;
+  }
 
   mIsReading = true;
   auto exitRead = MakeScopeExit([&] {
@@ -437,8 +449,9 @@ nsresult FileBlockCache::MoveBlock(int32_t aSourceBlockIndex, int32_t aDestBlock
 {
   MutexAutoLock mon(mDataMutex);
 
-  if (!mIsOpen)
+  if (!mThread) {
     return NS_ERROR_FAILURE;
+  }
 
   mBlockChanges.EnsureLengthAtLeast(std::max(aSourceBlockIndex, aDestBlockIndex) + 1);
 

dom/media/FileBlockCache.h

@@ -13,7 +13,7 @@
 #include "mozilla/UniquePtr.h"
 #include "mozilla/AbstractThread.h"
 #include "nsTArray.h"
-#include "MediaCache.h"
+#include "MediaBlockCacheBase.h"
 #include "nsDeque.h"
 #include "nsThreadUtils.h"
 #include <deque>
@@ -52,29 +52,23 @@ namespace mozilla {
 // changes listed in mBlockChanges to file. Read() checks mBlockChanges and
 // determines the current data to return, reading from file or from
 // mBlockChanges as necessary.
-class FileBlockCache : public Runnable {
+class FileBlockCache : public MediaBlockCacheBase
+{
 public:
-  enum {
-    BLOCK_SIZE = MediaCacheStream::BLOCK_SIZE
-  };
-
   FileBlockCache();
 
 protected:
-  ~FileBlockCache();
+  virtual ~FileBlockCache();
 
 public:
-  nsresult Init();
-
-  // Closes writer, shuts down thread.
-  void Close();
+  // Launch thread and open temporary file.
+  // If re-initializing, just discard pending writes if any.
+  nsresult Init() override;
 
   // Can be called on any thread. This defers to a non-main thread.
   nsresult WriteBlock(uint32_t aBlockIndex,
-    Span<const uint8_t> aData1, Span<const uint8_t> aData2);
-
-  // Performs block writes and block moves on its own thread.
-  NS_IMETHOD Run() override;
+                      Span<const uint8_t> aData1,
+                      Span<const uint8_t> aData2) override;
 
   // Synchronously reads data from file. May read from file or memory
   // depending on whether written blocks have been flushed to file yet.
@@ -82,11 +76,12 @@ public:
   nsresult Read(int64_t aOffset,
                 uint8_t* aData,
                 int32_t aLength,
-                int32_t* aBytes);
+                int32_t* aBytes) override;
 
   // Moves a block asynchronously. Can be called on any thread.
   // This defers file I/O to a non-main thread.
-  nsresult MoveBlock(int32_t aSourceBlockIndex, int32_t aDestBlockIndex);
+  nsresult MoveBlock(int32_t aSourceBlockIndex,
+                     int32_t aDestBlockIndex) override;
 
   // Represents a change yet to be made to a block in the file. The change
   // is either a write (and the data to be written is stored in this struct)
@@ -143,6 +138,12 @@ private:
 
   void SetCacheFile(PRFileDesc* aFD);
 
+  // Close file in thread and terminate thread.
+  void Close();
+
+  // Performs block writes and block moves on its own thread.
+  void PerformBlockIOs();
+
   // Mutex which controls access to mFD and mFDCurrentPos. Don't hold
   // mDataMutex while holding mFileMutex! mFileMutex must be owned
   // while accessing any of the following data fields or methods.
@@ -192,8 +193,6 @@ private:
   // True when a read is happening. Pending writes may be postponed, to give
   // higher priority to reads (which may be blocking the caller).
   bool mIsReading;
-  // True if the writer is ready to enqueue writes.
-  bool mIsOpen;
   // True if we've got a temporary file descriptor. Note: we don't use mFD
   // directly as that's synchronized via mFileMutex and we need to make
   // decisions about whether we can write while holding mDataMutex.

dom/media/MediaBlockCacheBase.h

@@ -0,0 +1,76 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#ifndef MEDIA_BLOCK_CACHE_BASE_H_
+#define MEDIA_BLOCK_CACHE_BASE_H_
+
+#include "MediaCache.h"
+#include "mozilla/Span.h"
+
+namespace mozilla {
+
+// Manages block management for the media cache. Data comes in over the network
+// via callbacks on the main thread, however we don't want to write the
+// incoming data to the media cache on the main thread, as this could block
+// causing UI jank.
+//
+// So MediaBlockCacheBase provides an abstraction for a temporary memory buffer or file accessible
+// as an array of blocks, which supports a block move operation, and
+// allows synchronous reading and writing from any thread, with writes being
+// buffered as needed so as not to block.
+//
+// Writes and cache block moves (which require reading) may be deferred to
+// their own non-main thread. This object also ensures that data which has
+// been scheduled to be written, but hasn't actually *been* written, is read
+// as if it had, i.e. pending writes are cached in readable memory until
+// they're flushed to file.
+//
+// To improve efficiency, writes can only be done at block granularity,
+// whereas reads can be done with byte granularity.
+//
+// Note it's also recommended not to read from the media cache from the main
+// thread to prevent jank.
+class MediaBlockCacheBase
+{
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(MediaBlockCacheBase)
+
+  static_assert(
+    MediaCacheStream::BLOCK_SIZE <
+      static_cast<decltype(MediaCacheStream::BLOCK_SIZE)>(INT32_MAX),
+    "MediaCacheStream::BLOCK_SIZE should fit in 31 bits");
+  static const int32_t BLOCK_SIZE = MediaCacheStream::BLOCK_SIZE;
+
+protected:
+  virtual ~MediaBlockCacheBase() {}
+
+public:
+  // Initialize this cache.
+  // If called again, re-initialize cache with minimal chance of failure.
+  virtual nsresult Init() = 0;
+
+  // Can be called on any thread. This defers to a non-main thread.
+  virtual nsresult WriteBlock(uint32_t aBlockIndex,
+                              Span<const uint8_t> aData1,
+                              Span<const uint8_t> aData2) = 0;
+
+  // Synchronously reads data from file. May read from file or memory
+  // depending on whether written blocks have been flushed to file yet.
+  // Not recommended to be called from the main thread, as can cause jank.
+  virtual nsresult Read(int64_t aOffset,
+                        uint8_t* aData,
+                        int32_t aLength,
+                        int32_t* aBytes) = 0;
+
+  // Moves a block asynchronously. Can be called on any thread.
+  // This defers file I/O to a non-main thread.
+  virtual nsresult MoveBlock(int32_t aSourceBlockIndex,
+                             int32_t aDestBlockIndex) = 0;
+};
+
+} // End namespace mozilla.
+
+#endif /* MEDIA_BLOCK_CACHE_BASE_H_ */

dom/media/MediaCache.h

@@ -198,15 +198,16 @@ public:
   MediaCacheStream(ChannelMediaResource* aClient, bool aIsPrivateBrowsing);
   ~MediaCacheStream();
 
-  // Set up this stream with the cache. Can fail on OOM. One
-  // of InitAsClone or Init must be called before any other method on
-  // this class. Does nothing if already initialized.
-  nsresult Init();
+  // Set up this stream with the cache. Can fail on OOM.
+  // aContentLength is the content length if known, otherwise -1.
+  // Exactly one of InitAsClone or Init must be called before any other method
+  // on this class. Does nothing if already initialized.
+  nsresult Init(int64_t aContentLength);
 
   // Set up this stream with the cache, assuming it's for the same data
-  // as the aOriginal stream. Can fail on OOM. Exactly one
-  // of InitAsClone or Init must be called before any other method on
-  // this class. Does nothing if already initialized.
+  // as the aOriginal stream. Can fail on OOM.
+  // Exactly one of InitAsClone or Init must be called before any other method
+  // on this class. Does nothing if already initialized.
   nsresult InitAsClone(MediaCacheStream* aOriginal);
 
   // These are called on the main thread.
@@ -438,11 +439,12 @@ private:
   // Update mPrincipal given that data has been received from aPrincipal
   bool UpdatePrincipal(nsIPrincipal* aPrincipal);
 
+  // Instance of MediaCache to use with this MediaCacheStream.
+  RefPtr<MediaCache> mMediaCache;
+
   // These fields are main-thread-only.
   ChannelMediaResource*  mClient;
   nsCOMPtr<nsIPrincipal> mPrincipal;
-  // Set to true when Init or InitAsClone has been called
-  bool                   mInitialized;
   // Set to true when MediaCache::Update() has finished while this stream
   // was present.
   bool                   mHasHadUpdate;

dom/media/MediaPrefs.h

@@ -87,6 +87,10 @@ private:
   // This is where DECL_MEDIA_PREF for each of the preferences should go.
 
   // Cache sizes.
+  DECL_MEDIA_PREF("media.memory_cache_max_size",              MediaMemoryCacheMaxSize, uint32_t, 8192);
+  DECL_MEDIA_PREF("media.memory_caches_combined_limit_kb",    MediaMemoryCachesCombinedLimitKb, uint32_t, 524288);
+  DECL_MEDIA_PREF("media.memory_caches_combined_limit_pc_sysmem",
+                                                              MediaMemoryCachesCombinedLimitPcSysmem, uint32_t, 5);
   DECL_MEDIA_PREF("media.cache.resource-index",               MediaResourceIndexCache, uint32_t, 8192);
 
   // AudioSink

dom/media/MediaResource.cpp

@@ -532,7 +532,17 @@ nsresult ChannelMediaResource::Open(nsIStreamListener **aStreamListener)
 {
   NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
 
-  nsresult rv = mCacheStream.Init();
+  int64_t cl = -1;
+  if (mChannel) {
+    nsCOMPtr<nsIHttpChannel> hc = do_QueryInterface(mChannel);
+    if (hc) {
+      if (NS_FAILED(hc->GetContentLength(&cl))) {
+        cl = -1;
+      }
+    }
+  }
+
+  nsresult rv = mCacheStream.Init(cl);
   if (NS_FAILED(rv))
     return rv;
   NS_ASSERTION(mOffset == 0, "Who set mOffset already?");

dom/media/MemoryBlockCache.cpp

@@ -0,0 +1,262 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#include "MemoryBlockCache.h"
+
+#include "MediaPrefs.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Logging.h"
+#include "prsystem.h"
+
+namespace mozilla {
+
+#undef LOG
+LazyLogModule gMemoryBlockCacheLog("MemoryBlockCache");
+#define LOG(x, ...)                                                            \
+  MOZ_LOG(gMemoryBlockCacheLog, LogLevel::Debug, ("%p " x, this, ##__VA_ARGS__))
+
+// Combined sizes of all MemoryBlockCache buffers.
+// Initialized to 0 by non-local static initialization.
+// Increases when a buffer grows (during initialization or unexpected OOB
+// writes), decreases when a MemoryBlockCache (with its buffer) is destroyed.
+static Atomic<size_t> mCombinedSizes;
+
+enum MemoryBlockCacheTelemetryErrors
+{
+  // Don't change order/numbers! Add new values at the end and update
+  // MEMORYBLOCKCACHE_ERRORS description in Histograms.json.
+  InitUnderuse = 0,
+  InitAllocation = 1,
+  ReadOverrun = 2,
+  WriteBlockOverflow = 3,
+  WriteBlockCannotGrow = 4,
+  MoveBlockSourceOverrun = 5,
+  MoveBlockDestOverflow = 6,
+  MoveBlockCannotGrow = 7,
+};
+
+MemoryBlockCache::MemoryBlockCache(int64_t aContentLength)
+  // Buffer whole blocks.
+  : mInitialContentLength((aContentLength >= 0) ? size_t(aContentLength) : 0)
+  , mMutex("MemoryBlockCache")
+  , mHasGrown(false)
+{
+  if (aContentLength <= 0) {
+    LOG("@%p MemoryBlockCache() "
+        "MEMORYBLOCKCACHE_ERRORS='InitUnderuse'",
+        this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          InitUnderuse);
+  }
+}
+
+MemoryBlockCache::~MemoryBlockCache()
+{
+  size_t sizes = static_cast<size_t>(mCombinedSizes -= mBuffer.Length());
+  LOG("~MemoryBlockCache() - destroying buffer of size %zu; combined sizes now "
+      "%zu",
+      mBuffer.Length(),
+      sizes);
+}
+
+bool
+MemoryBlockCache::EnsureBufferCanContain(size_t aContentLength)
+{
+  mMutex.AssertCurrentThreadOwns();
+  if (aContentLength == 0) {
+    return true;
+  }
+  const size_t initialLength = mBuffer.Length();
+  const size_t desiredLength =
+    ((aContentLength - 1) / BLOCK_SIZE + 1) * BLOCK_SIZE;
+  if (initialLength >= desiredLength) {
+    // Already large enough.
+    return true;
+  }
+  // Need larger buffer. If we are allowed more memory, attempt to re-allocate.
+  const size_t extra = desiredLength - initialLength;
+  // Note: There is a small race between testing `atomic + extra > limit` and
+  // committing to it with `atomic += extra` below; but this is acceptable, as
+  // in the worst case it may allow a small number of buffers to go past the
+  // limit.
+  // The alternative would have been to reserve the space first with
+  // `atomic += extra` and then undo it with `atomic -= extra` in case of
+  // failure; but this would have meant potentially preventing other (small but
+  // successful) allocations.
+  static const size_t sysmem =
+    std::max<size_t>(PR_GetPhysicalMemorySize(), 32 * 1024 * 1024);
+  const size_t limit = std::min(
+    size_t(MediaPrefs::MediaMemoryCachesCombinedLimitKb()) * 1024,
+    sysmem * MediaPrefs::MediaMemoryCachesCombinedLimitPcSysmem() / 100);
+  const size_t currentSizes = static_cast<size_t>(mCombinedSizes);
+  if (currentSizes + extra > limit) {
+    LOG("EnsureBufferCanContain(%zu) - buffer size %zu, wanted + %zu = %zu;"
+        " combined sizes %zu + %zu > limit %zu",
+        aContentLength,
+        initialLength,
+        extra,
+        desiredLength,
+        currentSizes,
+        extra,
+        limit);
+    return false;
+  }
+  if (!mBuffer.SetLength(desiredLength, mozilla::fallible)) {
+    LOG("EnsureBufferCanContain(%zu) - buffer size %zu, wanted + %zu = %zu, "
+        "allocation failed",
+        aContentLength,
+        initialLength,
+        extra,
+        desiredLength);
+    return false;
+  }
+  MOZ_ASSERT(mBuffer.Length() == desiredLength);
+  const size_t capacity = mBuffer.Capacity();
+  const size_t extraCapacity = capacity - desiredLength;
+  if (extraCapacity != 0) {
+    // Our buffer was given a larger capacity than the requested length, we may
+    // as well claim that extra capacity, both for our accounting, and to
+    // possibly bypass some future growths that would fit in this new capacity.
+    mBuffer.SetLength(capacity);
+  }
+  size_t newSizes =
+    static_cast<size_t>(mCombinedSizes += (extra + extraCapacity));
+  LOG("EnsureBufferCanContain(%zu) - buffer size %zu + requested %zu + bonus "
+      "%zu = %zu; combined "
+      "sizes %zu",
+      aContentLength,
+      initialLength,
+      extra,
+      extraCapacity,
+      capacity,
+      newSizes);
+  mHasGrown = true;
+  return true;
+}
+
+nsresult
+MemoryBlockCache::Init()
+{
+  MutexAutoLock lock(mMutex);
+  if (mBuffer.IsEmpty()) {
+    LOG("@%p Init()", this);
+    // Attempt to pre-allocate buffer for expected content length.
+    if (!EnsureBufferCanContain(mInitialContentLength)) {
+      LOG("@%p Init() MEMORYBLOCKCACHE_ERRORS='InitAllocation'", this);
+      Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                            InitAllocation);
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    LOG("@%p Init() again", this);
+    // Re-initialization - Just erase data.
+    MOZ_ASSERT(mBuffer.Length() >= mInitialContentLength);
+    memset(mBuffer.Elements(), 0, mBuffer.Length());
+  }
+  // Ignore initial growth.
+  mHasGrown = false;
+  return NS_OK;
+}
+
+nsresult
+MemoryBlockCache::WriteBlock(uint32_t aBlockIndex,
+                             Span<const uint8_t> aData1,
+                             Span<const uint8_t> aData2)
+{
+  MutexAutoLock lock(mMutex);
+
+  size_t offset = BlockIndexToOffset(aBlockIndex);
+  if (offset + aData1.Length() + aData2.Length() > mBuffer.Length() &&
+      !mHasGrown) {
+    LOG("@%p WriteBlock() "
+        "MEMORYBLOCKCACHE_ERRORS='WriteBlockOverflow'",
+        this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          WriteBlockOverflow);
+  }
+  if (!EnsureBufferCanContain(offset + aData1.Length() + aData2.Length())) {
+    LOG("%p WriteBlock() "
+        "MEMORYBLOCKCACHE_ERRORS='WriteBlockCannotGrow'",
+        this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          WriteBlockCannotGrow);
+    return NS_ERROR_FAILURE;
+  }
+
+  memcpy(mBuffer.Elements() + offset, aData1.Elements(), aData1.Length());
+  if (aData2.Length() > 0) {
+    memcpy(mBuffer.Elements() + offset + aData1.Length(),
+           aData2.Elements(),
+           aData2.Length());
+  }
+
+  return NS_OK;
+}
+
+nsresult
+MemoryBlockCache::Read(int64_t aOffset,
+                       uint8_t* aData,
+                       int32_t aLength,
+                       int32_t* aBytes)
+{
+  MutexAutoLock lock(mMutex);
+
+  MOZ_ASSERT(aOffset >= 0);
+  if (aOffset + aLength > int64_t(mBuffer.Length())) {
+    LOG("@%p Read() MEMORYBLOCKCACHE_ERRORS='ReadOverrun'", this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          ReadOverrun);
+    return NS_ERROR_FAILURE;
+  }
+
+  memcpy(aData, mBuffer.Elements() + aOffset, aLength);
+  *aBytes = aLength;
+
+  return NS_OK;
+}
+
+nsresult
+MemoryBlockCache::MoveBlock(int32_t aSourceBlockIndex, int32_t aDestBlockIndex)
+{
+  MutexAutoLock lock(mMutex);
+
+  size_t sourceOffset = BlockIndexToOffset(aSourceBlockIndex);
+  size_t destOffset = BlockIndexToOffset(aDestBlockIndex);
+  if (sourceOffset + BLOCK_SIZE > mBuffer.Length()) {
+    LOG("@%p MoveBlock() "
+        "MEMORYBLOCKCACHE_ERRORS='MoveBlockSourceOverrun'",
+        this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          MoveBlockSourceOverrun);
+    return NS_ERROR_FAILURE;
+  }
+  if (destOffset + BLOCK_SIZE > mBuffer.Length() && !mHasGrown) {
+    LOG("@%p MoveBlock() "
+        "MEMORYBLOCKCACHE_ERRORS='MoveBlockDestOverflow'",
+        this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          MoveBlockDestOverflow);
+  }
+  if (!EnsureBufferCanContain(destOffset + BLOCK_SIZE)) {
+    LOG("@%p MoveBlock() "
+        "MEMORYBLOCKCACHE_ERRORS='MoveBlockCannotGrow'",
+        this);
+    Telemetry::Accumulate(Telemetry::HistogramID::MEMORYBLOCKCACHE_ERRORS,
+                          MoveBlockCannotGrow);
+    return NS_ERROR_FAILURE;
+  }
+
+  memcpy(mBuffer.Elements() + destOffset,
+         mBuffer.Elements() + sourceOffset,
+         BLOCK_SIZE);
+
+  return NS_OK;
+}
+
+} // End namespace mozilla.
+
+// avoid redefined macro in unified build
+#undef LOG

dom/media/MemoryBlockCache.h

@@ -0,0 +1,83 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* 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/. */
+
+#ifndef MEMORY_BLOCK_CACHE_H_
+#define MEMORY_BLOCK_CACHE_H_
+
+#include "MediaBlockCacheBase.h"
+#include "mozilla/Mutex.h"
+
+namespace mozilla {
+
+// Manages block management for the media cache. Data comes in over the network
+// via callbacks on the main thread, however we don't want to write the
+// incoming data to the media cache on the main thread, as this could block
+// causing UI jank.
+//
+// So MediaBlockCacheBase provides an abstraction for a temporary memory buffer
+// as an array of blocks, which supports a block move operation, and
+// allows synchronous reading and writing from any thread.
+//
+// Writes and cache block moves (which require reading) may be deferred to
+// their own non-main thread. This object also ensures that data which has
+// been scheduled to be written, but hasn't actually *been* written, is read
+// as if it had, i.e. pending writes are cached in readable memory until
+// they're flushed to file.
+//
+// To improve efficiency, writes can only be done at block granularity,
+// whereas reads can be done with byte granularity.
+class MemoryBlockCache : public MediaBlockCacheBase
+{
+public:
+  explicit MemoryBlockCache(int64_t aContentLength);
+
+protected:
+  virtual ~MemoryBlockCache();
+
+public:
+  // Allocate initial buffer.
+  // If re-initializing, clear buffer.
+  virtual nsresult Init() override;
+
+  // Can be called on any thread.
+  virtual nsresult WriteBlock(uint32_t aBlockIndex,
+                              Span<const uint8_t> aData1,
+                              Span<const uint8_t> aData2) override;
+
+  // Synchronously reads data from buffer.
+  virtual nsresult Read(int64_t aOffset,
+                        uint8_t* aData,
+                        int32_t aLength,
+                        int32_t* aBytes) override;
+
+  // Moves a block. Can be called on any thread.
+  virtual nsresult MoveBlock(int32_t aSourceBlockIndex,
+                             int32_t aDestBlockIndex) override;
+
+private:
+  static size_t BlockIndexToOffset(uint32_t aBlockIndex)
+  {
+    return static_cast<size_t>(aBlockIndex) * BLOCK_SIZE;
+  }
+
+  // Ensure the buffer has at least a multiple of BLOCK_SIZE that can contain
+  // aContentLength bytes. Buffer size can only grow.
+  // Returns false if allocation failed.
+  bool EnsureBufferCanContain(size_t aContentLength);
+
+  // Initial content length.
+  const size_t mInitialContentLength;
+
+  // Mutex which controls access to all members below.
+  Mutex mMutex;
+
+  nsTArray<uint8_t> mBuffer;
+  bool mHasGrown;
+};
+
+} // End namespace mozilla.
+
+#endif /* MEMORY_BLOCK_CACHE_H_ */

dom/media/moz.build

@@ -135,6 +135,7 @@ EXPORTS += [
     'MediaTimer.h',
     'MediaTrack.h',
     'MediaTrackList.h',
+    'MemoryBlockCache.h',
     'MP3Decoder.h',
     'MP3Demuxer.h',
     'MP3FrameParser.h',
@@ -242,6 +243,7 @@ UNIFIED_SOURCES += [
     'MediaTimer.cpp',
     'MediaTrack.cpp',
     'MediaTrackList.cpp',
+    'MemoryBlockCache.cpp',
     'MP3Decoder.cpp',
     'MP3Demuxer.cpp',
     'MP3FrameParser.cpp',

dom/smil/nsSMILCSSProperty.cpp

@@ -69,7 +69,7 @@ nsSMILCSSProperty::GetBaseValue() const
   AnimationValue computedValue;
   if (mElement->IsStyledByServo()) {
     const ServoComputedValues* currentStyle =
-      mBaseStyleContext->StyleSource().AsServoComputedValues();
+      mBaseStyleContext->ComputedValues();
     computedValue.mServo =
       Servo_ComputedValues_ExtractAnimationValue(currentStyle, mPropID)
       .Consume();

dom/smil/nsSMILCSSValueType.cpp

@@ -701,7 +701,7 @@ ValueFromStringHelper(nsCSSPropertyID aPropID,
 
   // Get a suitable style context for Servo
   const ServoComputedValues* currentStyle =
-    aStyleContext->StyleSource().AsServoComputedValues();
+    aStyleContext->ComputedValues();
 
   // Compute value
   aPresContext->StyleSet()->AsServo()->GetAnimationValues(servoDeclarationBlock,

gfx/layers/wr/ScrollingLayersHelper.cpp

@@ -31,7 +31,25 @@ ScrollingLayersHelper::ScrollingLayersHelper(WebRenderLayer* aLayer,
 
   Layer* layer = mLayer->GetLayer();
   for (uint32_t i = layer->GetScrollMetadataCount(); i > 0; i--) {
+    const ScrollMetadata& metadata = layer->GetScrollMetadata(i - 1);
+    // The scroll clip on a given metadata is affected by all async transforms
+    // from metadatas "above" it, but not the async transform on the metadata
+    // itself. Therefore we need to push this clip before we push the
+    // corresponding scroll layer, so that when we set an async scroll position
+    // on the scroll layer, the clip isn't affected by it.
+    if (const Maybe<LayerClip>& clip = metadata.GetScrollClip()) {
+      PushLayerClip(clip.ref(), aStackingContext);
+    }
+
     const FrameMetrics& fm = layer->GetFrameMetrics(i - 1);
+    if (layer->GetIsFixedPosition() &&
+        layer->GetFixedPositionScrollContainerId() == fm.GetScrollId()) {
+      // If the layer contents are fixed for this metadata onwards, we need
+      // to insert the layer's local clip at this point in the clip tree,
+      // as a child of whatever's on the stack.
+      PushLayerLocalClip(aStackingContext);
+    }
+
     if (!fm.IsScrollable()) {
       continue;
     }
@@ -59,19 +77,8 @@ ScrollingLayersHelper::ScrollingLayersHelper(WebRenderLayer* aLayer,
   // on that layer. That is, the clip scrolls along with the content in
   // child layers. So we need to apply this after pushing all the scroll layers,
   // which we do above.
-  if (Maybe<LayerClip> scrolledClip = layer->GetScrolledClip()) {
-    LayerRect clipRect = IntRectToRect(ViewAs<LayerPixel>(
-        scrolledClip->GetClipRect(),
-        PixelCastJustification::MovingDownToChildren));
-    Maybe<WrImageMask> mask;
-    if (Maybe<size_t> maskLayerIndex = scrolledClip->GetMaskLayerIndex()) {
-      Layer* maskLayer = layer->GetAncestorMaskLayerAt(maskLayerIndex.value());
-      WebRenderLayer* maskWrLayer = WebRenderLayer::ToWebRenderLayer(maskLayer);
-      // TODO: check this transform is correct in all cases
-      mask = maskWrLayer->RenderMaskLayer(aStackingContext, maskLayer->GetTransform());
-    }
-    mBuilder->PushClip(aStackingContext.ToRelativeWrRect(clipRect),
-        mask.ptrOr(nullptr));
+  if (const Maybe<LayerClip>& scrolledClip = layer->GetScrolledClip()) {
+    PushLayerClip(scrolledClip.ref(), aStackingContext);
   }
 
   // If the layer is marked as fixed-position, it is fixed relative to something
@@ -79,18 +86,23 @@ ScrollingLayersHelper::ScrollingLayersHelper(WebRenderLayer* aLayer,
   // referred to as the "scroll container"). What this really means is that we
   // don't want this content to scroll with any scroll layer on the stack up to
   // and including the scroll container, but we do want it to scroll with any
-  // ancestor scroll layers. So we do a PushClipAndScrollInfo that maintains
+  // ancestor scroll layers.
+  // Also, the local clip on the layer (defined by layer->GetClipRect() and
+  // layer->GetMaskLayer()) also need to be fixed relative to the scroll
+  // container. This is why we inserted it into the clip tree during the
+  // loop above when we encountered the scroll container.
+  // At this point we do a PushClipAndScrollInfo that maintains
   // the current non-scrolling clip stack, but resets the scrolling clip stack
   // to the ancestor of the scroll container.
   if (layer->GetIsFixedPosition()) {
     FrameMetrics::ViewID fixedFor = layer->GetFixedPositionScrollContainerId();
     Maybe<FrameMetrics::ViewID> scrollsWith = mBuilder->ParentScrollIdFor(fixedFor);
-    Maybe<uint64_t> clipId = mBuilder->TopmostClipId();
+    Maybe<wr::WrClipId> clipId = mBuilder->TopmostClipId();
     // Default to 0 if there is no ancestor, because 0 refers to the root scrollframe.
     mBuilder->PushClipAndScrollInfo(scrollsWith.valueOr(0), clipId.ptrOr(nullptr));
+  } else {
+    PushLayerLocalClip(aStackingContext);
   }
-
-  PushLayerLocalClip(aStackingContext);
 }
 
 void
@@ -114,27 +126,54 @@ ScrollingLayersHelper::PushLayerLocalClip(const StackingContextHelper& aStacking
   }
 }
 
+void
+ScrollingLayersHelper::PushLayerClip(const LayerClip& aClip,
+                                     const StackingContextHelper& aSc)
+{
+  LayerRect clipRect = IntRectToRect(ViewAs<LayerPixel>(aClip.GetClipRect(),
+        PixelCastJustification::MovingDownToChildren));
+  Maybe<WrImageMask> mask;
+  if (Maybe<size_t> maskLayerIndex = aClip.GetMaskLayerIndex()) {
+    Layer* maskLayer = mLayer->GetLayer()->GetAncestorMaskLayerAt(maskLayerIndex.value());
+    WebRenderLayer* maskWrLayer = WebRenderLayer::ToWebRenderLayer(maskLayer);
+    // TODO: check this transform is correct in all cases
+    mask = maskWrLayer->RenderMaskLayer(aSc, maskLayer->GetTransform());
+  }
+  mBuilder->PushClip(aSc.ToRelativeWrRect(clipRect), mask.ptrOr(nullptr));
+}
+
 ScrollingLayersHelper::~ScrollingLayersHelper()
 {
   Layer* layer = mLayer->GetLayer();
-  if (mPushedLayerLocalClip) {
-    mBuilder->PopClip();
-  }
   if (!mLayer->WrManager()->AsyncPanZoomEnabled()) {
+    if (mPushedLayerLocalClip) {
+      mBuilder->PopClip();
+    }
     return;
   }
+
   if (layer->GetIsFixedPosition()) {
     mBuilder->PopClipAndScrollInfo();
+  } else if (mPushedLayerLocalClip) {
+    mBuilder->PopClip();
   }
   if (layer->GetScrolledClip()) {
     mBuilder->PopClip();
   }
-  for (int32_t i = layer->GetScrollMetadataCount(); i > 0; i--) {
-    const FrameMetrics& fm = layer->GetFrameMetrics(i - 1);
-    if (!fm.IsScrollable()) {
-      continue;
+  for (uint32_t i = 0; i < layer->GetScrollMetadataCount(); i++) {
+    const FrameMetrics& fm = layer->GetFrameMetrics(i);
+    if (fm.IsScrollable()) {
+      mBuilder->PopScrollLayer();
+    }
+    if (layer->GetIsFixedPosition() &&
+        layer->GetFixedPositionScrollContainerId() == fm.GetScrollId() &&
+        mPushedLayerLocalClip) {
+      mBuilder->PopClip();
+    }
+    const ScrollMetadata& metadata = layer->GetScrollMetadata(i);
+    if (metadata.GetScrollClip()) {
+      mBuilder->PopClip();
     }
-    mBuilder->PopScrollLayer();
   }
 }
 

gfx/layers/wr/ScrollingLayersHelper.h

@@ -16,6 +16,7 @@ class DisplayListBuilder;
 
 namespace layers {
 
+struct LayerClip;
 class StackingContextHelper;
 class WebRenderLayer;
 
@@ -29,6 +30,8 @@ public:
 
 private:
   void PushLayerLocalClip(const StackingContextHelper& aStackingContext);
+  void PushLayerClip(const LayerClip& aClip,
+                     const StackingContextHelper& aSc);
 
   WebRenderLayer* mLayer;
   wr::DisplayListBuilder* mBuilder;

gfx/webrender_bindings/WebRenderAPI.cpp

@@ -587,13 +587,13 @@ DisplayListBuilder::PushClip(const WrRect& aClipRect,
   WRDL_LOG("PushClip id=%" PRIu64 " r=%s m=%p b=%s\n", clip_id,
       Stringify(aClipRect).c_str(), aMask,
       aMask ? Stringify(aMask->rect).c_str() : "none");
-  mClipIdStack.push_back(clip_id);
+  mClipIdStack.push_back(WrClipId { clip_id });
 }
 
 void
 DisplayListBuilder::PopClip()
 {
-  WRDL_LOG("PopClip id=%" PRIu64 "\n", mClipIdStack.back());
+  WRDL_LOG("PopClip id=%" PRIu64 "\n", mClipIdStack.back().id);
   mClipIdStack.pop_back();
   wr_dp_pop_clip(mWrState);
 }
@@ -627,11 +627,12 @@ DisplayListBuilder::PopScrollLayer()
 
 void
 DisplayListBuilder::PushClipAndScrollInfo(const layers::FrameMetrics::ViewID& aScrollId,
-                                          const uint64_t* aClipId)
+                                          const WrClipId* aClipId)
 {
   WRDL_LOG("PushClipAndScroll s=%" PRIu64 " c=%s\n", aScrollId,
-      aClipId ? Stringify(*aClipId).c_str() : "none");
-  wr_dp_push_clip_and_scroll_info(mWrState, aScrollId, aClipId);
+      aClipId ? Stringify(aClipId->id).c_str() : "none");
+  wr_dp_push_clip_and_scroll_info(mWrState, aScrollId,
+      aClipId ? &(aClipId->id) : nullptr);
 }
 
 void
@@ -891,7 +892,7 @@ DisplayListBuilder::PushClipRegion(const WrRect& aMain,
                                 aMask);
 }
 
-Maybe<uint64_t>
+Maybe<WrClipId>
 DisplayListBuilder::TopmostClipId()
 {
   if (mClipIdStack.empty()) {

gfx/webrender_bindings/WebRenderAPI.h

@@ -168,7 +168,7 @@ public:
   void PopScrollLayer();
 
   void PushClipAndScrollInfo(const layers::FrameMetrics::ViewID& aScrollId,
-                             const uint64_t* aClipId);
+                             const WrClipId* aClipId);
   void PopClipAndScrollInfo();
 
   void PushRect(const WrRect& aBounds,
@@ -292,7 +292,7 @@ public:
   // Returns the clip id that was most recently pushed with PushClip and that
   // has not yet been popped with PopClip. Return Nothing() if the clip stack
   // is empty.
-  Maybe<uint64_t> TopmostClipId();
+  Maybe<WrClipId> TopmostClipId();
   // Returns the scroll id that was pushed just before the given scroll id.
   // If the given scroll id is not in the stack of active scrolled layers, or if
   // it is the rootmost scroll id (and therefore has no ancestor), this function
@@ -308,7 +308,7 @@ protected:
   // (by PushClip and PushScrollLayer, respectively) and are still active.
   // This is helpful for knowing e.g. what the ancestor scroll id of a particular
   // scroll id is, and doing other "queries" of current state.
-  std::vector<uint64_t> mClipIdStack;
+  std::vector<WrClipId> mClipIdStack;
   std::vector<layers::FrameMetrics::ViewID> mScrollIdStack;
 
   friend class WebRenderAPI;

gfx/webrender_bindings/WebRenderTypes.h

@@ -604,6 +604,14 @@ static inline WrFilterOp ToWrFilterOp(const layers::CSSFilter& filter) {
   };
 }
 
+// Corresponds to an "internal" webrender clip id. That is, a
+// ClipId::Clip(x,pipeline_id) maps to a WrClipId{x}. We use a struct wrapper
+// instead of a typedef so that this is a distinct type from FrameMetrics::ViewID
+// and the compiler will catch accidental conversions between the two.
+struct WrClipId {
+  uint64_t id;
+};
+
 } // namespace wr
 } // namespace mozilla
 

js/src/old-configure.in

@@ -181,7 +181,6 @@ case "$target" in
         case "$CC_VERSION" in
         19*)
             _CC_SUITE=14
-            MSVS_VERSION=2015
             MSVC_C_RUNTIME_DLL=vcruntime140.dll
             MSVC_CXX_RUNTIME_DLL=msvcp140.dll
 
@@ -195,7 +194,6 @@ case "$target" in
             CXXFLAGS="$CXXFLAGS -Zc:sizedDealloc-"
             ;;
         esac
-        AC_SUBST(MSVS_VERSION)
         AC_SUBST(MSVC_C_RUNTIME_DLL)
         AC_SUBST(MSVC_CXX_RUNTIME_DLL)
 

js/xpconnect/src/XPCComponents.cpp

@@ -2503,10 +2503,12 @@ nsXPCComponents_Utils::Import(const nsACString& registryLocation,
     if (!moduleloader)
         return NS_ERROR_FAILURE;
 
+#ifdef MOZ_GECKO_PROFILER
     const nsCString& flatLocation = PromiseFlatCString(registryLocation);
     PROFILER_LABEL_DYNAMIC("Components.utils", "import",
                            js::ProfileEntry::Category::OTHER,
                            flatLocation.get());
+#endif
 
     return moduleloader->Import(registryLocation, targetObj, cx, optionalArgc, retval);
 }

layout/base/GeckoRestyleManager.cpp

@@ -13,6 +13,7 @@
 #include <algorithm> // For std::max
 #include "gfxContext.h"
 #include "mozilla/EffectSet.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/EventStates.h"
 #include "mozilla/ViewportFrame.h"
 #include "mozilla/css/StyleRule.h" // For nsCSSSelector
@@ -23,6 +24,7 @@
 #include "nsAutoPtr.h"
 #include "nsStyleChangeList.h"
 #include "nsRuleProcessorData.h"
+#include "nsStyleContextInlines.h"
 #include "nsStyleSet.h"
 #include "nsStyleUtil.h"
 #include "nsCSSFrameConstructor.h"
@@ -1767,7 +1769,7 @@ ElementRestyler::Restyle(nsRestyleHint aRestyleHint)
                                   eRestyle_Subtree |
                                   eRestyle_ForceDescendants));
 
-  RefPtr<nsStyleContext> oldContext = mFrame->StyleContext();
+  RefPtr<GeckoStyleContext> oldContext = mFrame->StyleContext()->AsGecko();
 
   nsTArray<SwapInstruction> swaps;
 
@@ -1916,7 +1918,7 @@ ElementRestyler::Restyle(nsRestyleHint aRestyleHint)
     for (SwapInstruction& swap : swaps) {
       LOG_RESTYLE("swapping style structs between %p and %p",
                   swap.mOldContext.get(), swap.mNewContext.get());
-      swap.mOldContext->SwapStyleData(swap.mNewContext, swap.mStructsToSwap);
+      swap.mOldContext->AsGecko()->SwapStyleData(swap.mNewContext->AsGecko(), swap.mStructsToSwap);
       swappedStructs |= swap.mStructsToSwap;
     }
     swaps.Clear();
@@ -2751,7 +2753,7 @@ ElementRestyler::RestyleSelf(nsIFrame* aSelf,
           } else {
             LOG_RESTYLE("swapping style structs between %p and %p",
                         oldContext.get(), newContext.get());
-            oldContext->SwapStyleData(newContext, equalStructs);
+            oldContext->AsGecko()->SwapStyleData(newContext->AsGecko(), equalStructs);
             *aSwappedStructs |= equalStructs;
           }
 #ifdef RESTYLE_LOGGING
@@ -2759,9 +2761,9 @@ ElementRestyler::RestyleSelf(nsIFrame* aSelf,
           if (structs) {
             LOG_RESTYLE_INDENT();
             LOG_RESTYLE("old style context now has: %s",
-                        oldContext->GetCachedStyleDataAsString(structs).get());
+                        oldContext->AsGecko()->GetCachedStyleDataAsString(structs).get());
             LOG_RESTYLE("new style context now has: %s",
-                        newContext->GetCachedStyleDataAsString(structs).get());
+                        newContext->AsGecko()->GetCachedStyleDataAsString(structs).get());
           }
 #endif
         }
@@ -3443,7 +3445,7 @@ ClearCachedInheritedStyleDataOnDescendants(
   for (size_t i = 0; i < aContextsToClear.Length(); i++) {
     auto& entry = aContextsToClear[i];
     if (!entry.mStyleContext->HasSingleReference()) {
-      entry.mStyleContext->ClearCachedInheritedStyleDataOnDescendants(
+      entry.mStyleContext->AsGecko()->ClearCachedInheritedStyleDataOnDescendants(
           entry.mStructs);
     }
     entry.mStyleContext = nullptr;

layout/base/RestyleTracker.cpp

@@ -88,7 +88,7 @@ RestyleTracker::ProcessOneRestyle(Element* aElement,
         GeckoRestyleManager::StructsToLog() != 0) {
       LOG_RESTYLE("style context tree before restyle:");
       LOG_RESTYLE_INDENT();
-      primaryFrame->StyleContext()->LogStyleContextTree(
+      primaryFrame->StyleContext()->AsGecko()->LogStyleContextTree(
           LoggingDepth(), GeckoRestyleManager::StructsToLog());
     }
 #endif

layout/base/ServoRestyleManager.cpp

@@ -382,7 +382,7 @@ ServoRestyleManager::ProcessPostTraversal(Element* aElement,
   // elements, though that is buggy right now even in non-stylo mode, see
   // bug 1251799.
   const bool recreateContext = oldStyleContext &&
-    oldStyleContext->StyleSource().AsServoComputedValues() != computedValues;
+    oldStyleContext->ComputedValues() != computedValues;
 
   RefPtr<nsStyleContext> newContext = nullptr;
   if (recreateContext) {

layout/base/nsCSSFrameConstructor.cpp

@@ -86,6 +86,7 @@
 #include "nsAutoLayoutPhase.h"
 #include "nsStyleStructInlines.h"
 #include "nsPageContentFrame.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/RestyleManager.h"
 #include "mozilla/RestyleManagerInlines.h"
 #include "StickyScrollContainer.h"

layout/base/nsPresArena.cpp

@@ -13,7 +13,7 @@
 #include "nsDebug.h"
 #include "nsArenaMemoryStats.h"
 #include "nsPrintfCString.h"
-#include "nsStyleContext.h"
+#include "GeckoStyleContext.h"
 #include "FrameLayerBuilder.h"
 #include "mozilla/ArrayUtils.h"
 
@@ -208,7 +208,7 @@ nsPresArena::AddSizeOfExcludingThis(mozilla::MallocSizeOf aMallocSizeOf,
       case eArenaObjectID_nsRuleNode:
         p = &aArenaStats->mRuleNodes;
         break;
-      case eArenaObjectID_nsStyleContext:
+      case eArenaObjectID_GeckoStyleContext:
         p = &aArenaStats->mStyleContexts;
         break;
 #define STYLE_STRUCT(name_, checkdata_cb_)      \

layout/base/nsPresArenaObjectList.h

@@ -47,7 +47,7 @@
 
 PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(nsLineBox)
 PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(nsRuleNode)
-PRES_ARENA_OBJECT_WITH_ARENAREFPTR_SUPPORT(nsStyleContext)
+PRES_ARENA_OBJECT_WITH_ARENAREFPTR_SUPPORT(GeckoStyleContext)
 PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(DisplayItemData)
 PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(nsInheritedStyleData)
 PRES_ARENA_OBJECT_WITHOUT_ARENAREFPTR_SUPPORT(nsResetStyleData)

layout/generic/WritingModes.h

@@ -8,6 +8,7 @@
 
 #include "nsRect.h"
 #include "nsStyleContext.h"
+#include "nsStyleContextInlines.h"
 #include "nsBidiUtils.h"
 
 // It is the caller's responsibility to operate on logical-coordinate objects

layout/generic/nsFrame.cpp

@@ -42,6 +42,7 @@
 #include "nsFrameManager.h"
 #include "nsLayoutUtils.h"
 #include "LayoutLogging.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/GeckoRestyleManager.h"
 #include "mozilla/RestyleManager.h"
 #include "mozilla/RestyleManagerInlines.h"
@@ -7197,7 +7198,7 @@ nsIFrame::ListGeneric(nsACString& aTo, const char* aPrefix, uint32_t aFlags) con
       pseudoTag->ToString(atomString);
       aTo += nsPrintfCString("%s", NS_LossyConvertUTF16toASCII(atomString).get());
     }
-    if (mStyleContext->StyleSource().IsGeckoRuleNodeOrNull()) {
+    if (mStyleContext->IsGecko()) {
       if (!mStyleContext->GetParent() ||
           (GetParent() && GetParent()->StyleContext() != mStyleContext->GetParent())) {
         aTo += nsPrintfCString("^%p", mStyleContext->GetParent());

layout/generic/nsIFrame.h

@@ -41,6 +41,7 @@
 #include "nsStyleStruct.h"
 #include "Visibility.h"
 #include "nsChangeHint.h"
+#include "nsStyleContextInlines.h"
 
 #ifdef ACCESSIBILITY
 #include "mozilla/a11y/AccTypes.h"

layout/inspector/inDOMUtils.cpp

@@ -243,14 +243,13 @@ inDOMUtils::GetCSSStyleRules(nsIDOMElement *aElement,
     return NS_OK;
   }
 
-  NonOwningStyleContextSource source = styleContext->StyleSource();
-  if (source.IsNull()) {
-    return NS_OK;
-  }
 
   nsCOMPtr<nsIMutableArray> rules = nsArray::Create();
-  if (source.IsGeckoRuleNodeOrNull()) {
-    nsRuleNode* ruleNode = source.AsGeckoRuleNode();
+  if (auto gecko = styleContext->GetAsGecko()) {
+    nsRuleNode* ruleNode = gecko->RuleNode();
+    if (!ruleNode) {
+      return NS_OK;
+    }
 
     AutoTArray<nsRuleNode*, 16> ruleNodes;
     while (!ruleNode->IsRoot()) {

layout/reftests/bugs/1066554-1.html

@@ -7,15 +7,17 @@
   <script>
     function insertShadowSVG() {
       var x = document.getElementById("x");
-      x.createShadowRoot();
-      x.shadowRoot.innerHTML =
-        '<svg width="50px" height="10px"> \
-           <switch> \
-             <foreignObject width="50px" height="50px"> \
-               <div style="width: 100px; height: 10px; background: red;"></div> \
-             </foreignObject> \
-           </switch> \
-         </svg>';
+      if (x.createShadowRoot) {
+        x.createShadowRoot();
+        x.shadowRoot.innerHTML =
+          '<svg width="50px" height="10px"> \
+             <switch> \
+               <foreignObject width="50px" height="50px"> \
+                 <div style="width: 100px; height: 10px; background: red;"></div> \
+               </foreignObject> \
+             </switch> \
+           </svg>';
+      }
       document.documentElement.removeAttribute("class");
     }
     window.addEventListener("MozReftestInvalidate", insertShadowSVG);

layout/reftests/bugs/reftest.list

@@ -1856,7 +1856,7 @@ test-pref(layout.css.grid.enabled,true) == 1053035-1-grid.html 1053035-1-ref.htm
 == 1062108-1.html 1062108-1-ref.html
 == 1062792-1.html 1062792-1-ref.html
 == 1062963-floatmanager-reflow.html 1062963-floatmanager-reflow-ref.html
-test-pref(dom.webcomponents.enabled,true) == 1066554-1.html 1066554-1-ref.html
+test-pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == 1066554-1.html 1066554-1-ref.html
 == 1069716-1.html 1069716-1-ref.html
 fails-if(webrender) == 1078262-1.html about:blank
 test-pref(layout.testing.overlay-scrollbars.always-visible,false) == 1081072-1.html 1081072-1-ref.html

layout/reftests/css-display/display-contents-shadow-dom-1.html

@@ -76,38 +76,40 @@ div.after::after {content: " Y";}
         return e;
       }
 
-      document.body.offsetHeight;
+      function run() {
+        document.body.offsetHeight;
 
-      shadow("host1").innerHTML = '<content></content> c';
-      shadow("host2").innerHTML = 'a <content style="display:contents"></content> c';
-      shadow("host3").innerHTML = 'a <content style="display:contents"></content>';
-      shadow("host4").innerHTML = '<content style="display:contents"></content>';
-      shadow("host5").innerHTML = 'a <content style="display:contents"></content>';
-      shadow("host6").innerHTML = '<z style="color:blue; display:contents"><content></content></z> c';
-      shadow("host7").innerHTML = 'a <content style="display:contents"></content> c';
-      shadow("host8").innerHTML = 'a <z style="color:blue; display:contents"><content style="display:contents"></z></content>';
-      shadow("host9").innerHTML = '<content style="display:contents"></content>';
-      shadow("hostA").innerHTML = 'a <content style="display:contents"></content>';
-      shadow("hostB").innerHTML = 'a <content select=".c"></content> <content select=".b"></content> B';
-      shadow("hostC").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B';
-      shadow("hostD").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B <content select=".b"></content>';
-      shadow("hostE").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B';
-      shadow("hostF").innerHTML = '<content select=".c"></content> <content select=".b"></content> B';
-      shadow("hostG").innerHTML = '<content select=".b"></content>';
-      shadow("hostH").innerHTML = '<content select=".b"></content>';
-      shadow("hostI").innerHTML = 'A<content select=".b"></content>';
-      shadow("hostJ").innerHTML = 'A<content select=".b"></content>';
-      shadow("hostK").innerHTML = '<content select=".b"></content>';
-      shadow("hostL").innerHTML = '<content select=".b"></content>';
-      shadow("hostM").innerHTML = '<content select="b"></content><content select="i"></content>';
-      shadow("hostN").innerHTML = '<content select="b"></content><content select="i"></content>';
-      shadow("hostO").innerHTML = '<content select="b"></content><content select="i"></content>';
-      shadow("hostP").innerHTML = '<content select="b"></content><content select="i"></content>';
-      shadow("hostQ").innerHTML = '<content select="b"></content><content select="i"></content>';
-      shadow("hostR").innerHTML = '<content select="span"></content>';
-      shadow("hostW").innerHTML = '<z style="color:red"><content select="b"></content></z>';
-      shadow("hostX").innerHTML = '<z style="color:red"><content select="b"></content></z>';
-      // TODO(bug 1021572?) shadow("hostY").innerHTML = '<content select="b"><style scoped>:scope{color:green}</style></content>';
+        shadow("host1").innerHTML = '<content></content> c';
+        shadow("host2").innerHTML = 'a <content style="display:contents"></content> c';
+        shadow("host3").innerHTML = 'a <content style="display:contents"></content>';
+        shadow("host4").innerHTML = '<content style="display:contents"></content>';
+        shadow("host5").innerHTML = 'a <content style="display:contents"></content>';
+        shadow("host6").innerHTML = '<z style="color:blue; display:contents"><content></content></z> c';
+        shadow("host7").innerHTML = 'a <content style="display:contents"></content> c';
+        shadow("host8").innerHTML = 'a <z style="color:blue; display:contents"><content style="display:contents"></z></content>';
+        shadow("host9").innerHTML = '<content style="display:contents"></content>';
+        shadow("hostA").innerHTML = 'a <content style="display:contents"></content>';
+        shadow("hostB").innerHTML = 'a <content select=".c"></content> <content select=".b"></content> B';
+        shadow("hostC").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B';
+        shadow("hostD").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B <content select=".b"></content>';
+        shadow("hostE").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B';
+        shadow("hostF").innerHTML = '<content select=".c"></content> <content select=".b"></content> B';
+        shadow("hostG").innerHTML = '<content select=".b"></content>';
+        shadow("hostH").innerHTML = '<content select=".b"></content>';
+        shadow("hostI").innerHTML = 'A<content select=".b"></content>';
+        shadow("hostJ").innerHTML = 'A<content select=".b"></content>';
+        shadow("hostK").innerHTML = '<content select=".b"></content>';
+        shadow("hostL").innerHTML = '<content select=".b"></content>';
+        shadow("hostM").innerHTML = '<content select="b"></content><content select="i"></content>';
+        shadow("hostN").innerHTML = '<content select="b"></content><content select="i"></content>';
+        shadow("hostO").innerHTML = '<content select="b"></content><content select="i"></content>';
+        shadow("hostP").innerHTML = '<content select="b"></content><content select="i"></content>';
+        shadow("hostQ").innerHTML = '<content select="b"></content><content select="i"></content>';
+        shadow("hostR").innerHTML = '<content select="span"></content>';
+        shadow("hostW").innerHTML = '<z style="color:red"><content select="b"></content></z>';
+        shadow("hostX").innerHTML = '<z style="color:red"><content select="b"></content></z>';
+        // TODO(bug 1021572?) shadow("hostY").innerHTML = '<content select="b"><style scoped>:scope{color:green}</style></content>';
+      }
 
       function tweak() {
         document.body.offsetHeight;
@@ -230,7 +232,12 @@ div.after::after {content: " Y";}
           },0);
       }
 
-      window.addEventListener("MozReftestInvalidate", tweak);
+      if (document.body.createShadowRoot) {
+        run();
+        window.addEventListener("MozReftestInvalidate", tweak);
+      } else {
+        document.documentElement.removeAttribute("class");
+      }
     </script>
   </body>
 </html>

layout/reftests/css-display/reftest.list

@@ -5,8 +5,8 @@ fuzzy-if(Android,8,604) == display-contents-acid.html display-contents-acid-ref.
 fuzzy-if(Android,8,604) == display-contents-acid-dyn-1.html display-contents-acid-ref.html
 fuzzy-if(Android,8,604) == display-contents-acid-dyn-2.html display-contents-acid-ref.html
 fuzzy-if(Android,8,604) == display-contents-acid-dyn-3.html display-contents-acid-ref.html
-skip-if(styloVsGecko||stylo) == display-contents-generated-content.html display-contents-generated-content-ref.html
-skip-if(styloVsGecko||stylo) == display-contents-generated-content-2.html display-contents-generated-content-ref.html
+== display-contents-generated-content.html display-contents-generated-content-ref.html
+== display-contents-generated-content-2.html display-contents-generated-content-ref.html
 fails-if(styloVsGecko||stylo) == display-contents-style-inheritance-1.html display-contents-style-inheritance-1-ref.html
 fails-if(styloVsGecko||stylo) == display-contents-style-inheritance-1-stylechange.html display-contents-style-inheritance-1-ref.html
 fuzzy-if(winWidget,12,100) skip-if(styloVsGecko||stylo) == display-contents-style-inheritance-1-dom-mutations.html display-contents-style-inheritance-1-ref.html
@@ -17,7 +17,7 @@ fuzzy-if(winWidget,12,100) skip-if(styloVsGecko||stylo) == display-contents-styl
 == display-contents-visibility-hidden-2.html display-contents-visibility-hidden-ref.html
 == display-contents-495385-2d.html display-contents-495385-2d-ref.html
 fuzzy-if(Android,7,3935) == display-contents-xbl.xhtml display-contents-xbl-ref.html
-fuzzy-if(Android,7,1186) pref(dom.webcomponents.enabled,true) skip-if(styloVsGecko||stylo) == display-contents-shadow-dom-1.html display-contents-shadow-dom-1-ref.html
+fuzzy-if(Android,7,1186) pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == display-contents-shadow-dom-1.html display-contents-shadow-dom-1-ref.html
 == display-contents-xbl-2.xul display-contents-xbl-2-ref.xul
 asserts(1) asserts-if(styloVsGecko,2) == display-contents-xbl-3.xul display-contents-xbl-3-ref.xul # bug 1089223
 skip == display-contents-xbl-4.xul display-contents-xbl-4-ref.xul # fails (not just asserts) due to bug 1089223

layout/reftests/forms/legend/reftest.list

@@ -1,4 +1,4 @@
 == legend.html legend-ref.html
-fuzzy-if(skiaContent,1,7) pref(dom.webcomponents.enabled,true) fails-if(styloVsGecko||stylo) == shadow-dom.html shadow-dom-ref.html
+fuzzy-if(skiaContent,1,7) pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == shadow-dom.html shadow-dom-ref.html
 == 1273433.html 1273433-ref.html
 fails-if(styloVsGecko||stylo) == 1339287.html 1339287-ref.html

layout/reftests/forms/legend/shadow-dom.html

@@ -48,17 +48,19 @@ div.after::after {content: " Y";}
         return e;
       }
 
-      document.body.offsetHeight;
+      function run() {
+        document.body.offsetHeight;
 
-      shadow("host1").innerHTML = '<content></content> c';
-      shadow("host2").innerHTML = 'a <content></content> c';
-      shadow("host3").innerHTML = 'a <content></content>';
-      shadow("host4").innerHTML = '<content></content>';
-      shadow("host5").innerHTML = 'a <content></content>';
-      shadow("host6").innerHTML = '<z style="color:blue; display:contents"><content></content></z> c';
-      shadow("host7").innerHTML = 'a <content select=".c"></content> <content select=".b"></content> B';
-      shadow("host8").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B';
-      shadow("host9").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B <content select=".b"></content>';
+        shadow("host1").innerHTML = '<content></content> c';
+        shadow("host2").innerHTML = 'a <content></content> c';
+        shadow("host3").innerHTML = 'a <content></content>';
+        shadow("host4").innerHTML = '<content></content>';
+        shadow("host5").innerHTML = 'a <content></content>';
+        shadow("host6").innerHTML = '<z style="color:blue; display:contents"><content></content></z> c';
+        shadow("host7").innerHTML = 'a <content select=".c"></content> <content select=".b"></content> B';
+        shadow("host8").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B';
+        shadow("host9").innerHTML = 'A <content select=".c"></content> <content select=".b"></content> B <content select=".b"></content>';
+      }
 
       function tweak() {
         document.body.offsetHeight;
@@ -105,7 +107,12 @@ div.after::after {content: " Y";}
           },0);
       }
 
-      window.addEventListener("MozReftestInvalidate", tweak);
+      if (document.body.createShadowRoot) {
+        run();
+        window.addEventListener("MozReftestInvalidate", tweak);
+      } else {
+        document.documentElement.removeAttribute("class");
+      }
     </script>
   </body>
 </html>

layout/reftests/mathml/reftest.list

@@ -367,7 +367,7 @@ fuzzy-if(OSX,1,100) fuzzy-if(skiaContent,1,14) == mfrac-D-1.html mfrac-D-1-ref.h
 == mfrac-D-3.html mfrac-D-3-ref.html
 == mfrac-D-4.html mfrac-D-4-ref.html
 == mfrac-E-1.html mfrac-E-1-ref.html
-test-pref(dom.webcomponents.enabled,true) == shadow-dom-1.html shadow-dom-1-ref.html
+test-pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == shadow-dom-1.html shadow-dom-1-ref.html
 pref(font.size.inflation.emPerLine,25) == font-inflation-1.html font-inflation-1-ref.html
 test-pref(font.minimum-size.x-math,40) == default-font.html default-font-ref.html
 != radicalbar-1.html about:blank

layout/reftests/mathml/shadow-dom-1.html

@@ -7,9 +7,11 @@
   <script>
     function insertShadowMathML() {
       var x = document.getElementById("x");
-      x.createShadowRoot();
-      x.shadowRoot.innerHTML =
-        '<math><msup><mi>X</mi><mi>X</mi></msup></math>';
+      if (x.createShadowRoot) {
+        x.createShadowRoot();
+        x.shadowRoot.innerHTML =
+          '<math><msup><mi>X</mi><mi>X</mi></msup></math>';
+      }
       document.documentElement.removeAttribute("class");
     }
     window.addEventListener("MozReftestInvalidate", insertShadowMathML);

layout/reftests/webcomponents/cross-tree-selection-1.html

@@ -3,6 +3,11 @@
 <head>
   <script>
     function tweak() {
+      if (!document.body.createShadowRoot) {
+        document.documentElement.className = "";
+        return;
+      }
+
       var host = document.getElementById("host");
       var shadow = host.createShadowRoot();
 

layout/reftests/webcomponents/dynamic-insertion-point-distribution-1.html

@@ -5,9 +5,13 @@
   <body>
     <div id="host"></div>
     <script>
-      var host = document.getElementById("host");
-      var root = host.createShadowRoot();
-      root.innerHTML = 'a <content></content> c';
+      var host, root;
+
+      function run() {
+        host = document.getElementById("host");
+        root = host.createShadowRoot();
+        root.innerHTML = 'a <content></content> c';
+      }
 
       function tweak() {
         var span = document.createElement("span");
@@ -19,7 +23,12 @@
         document.documentElement.removeAttribute("class");
       }
 
-      window.addEventListener("MozReftestInvalidate", tweak);
+      if (document.body.createShadowRoot) {
+        run();
+        window.addEventListener("MozReftestInvalidate", tweak);
+      } else {
+        document.documentElement.className = "";
+      }
     </script>
   </body>
 </html>

layout/reftests/webcomponents/dynamic-insertion-point-distribution-2.html

@@ -5,9 +5,13 @@
   <body>
     <div id="host"></div>
     <script>
-      var host = document.getElementById("host");
-      var root = host.createShadowRoot();
-      root.innerHTML = "<span>a</span>";
+      var host, root;
+
+      function run() {
+        host = document.getElementById("host");
+        root = host.createShadowRoot();
+        root.innerHTML = "<span>a</span>";
+      }
 
       function tweak() {
         var span = document.createElement("span");
@@ -20,7 +24,12 @@
         document.documentElement.removeAttribute("class");
       }
 
-      window.addEventListener("MozReftestInvalidate", tweak);
+      if (document.body.createShadowRoot) {
+        run();
+        window.addEventListener("MozReftestInvalidate", tweak);
+      } else {
+        document.documentElement.className = "";
+      }
     </script>
   </body>
 </html>

layout/reftests/webcomponents/input-transition-1.html

@@ -5,9 +5,13 @@
   <body>
     <div id="host"></div>
     <script>
-      var host = document.getElementById("host");
-      var root = host.createShadowRoot();
-      root.innerHTML = '<style>input ~ div { background: red; transition: background 100ms; } input:checked ~ div { background: green; }</style><input id="one" type="checkbox"><div style="height: 50px; width: 50px;"></div>';
+      var host, root;
+
+      function run() {
+        host = document.getElementById("host");
+        root = host.createShadowRoot();
+        root.innerHTML = '<style>input ~ div { background: red; transition: background 100ms; } input:checked ~ div { background: green; }</style><input id="one" type="checkbox"><div style="height: 50px; width: 50px;"></div>';
+      }
 
       function tweak() {
           var el = root.getElementById("one");
@@ -17,7 +21,12 @@
           });
       }
 
-      window.addEventListener("MozReftestInvalidate", tweak);
+      if (document.body.createShadowRoot) {
+        run();
+        window.addEventListener("MozReftestInvalidate", tweak);
+      } else {
+        document.documentElement.className = "";
+      }
     </script>
   </body>
 </html>

layout/reftests/webcomponents/reftest.list

@@ -1,19 +1,19 @@
-pref(dom.webcomponents.enabled,true) == cross-tree-selection-1.html cross-tree-selection-1-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-1.html basic-shadow-1-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-2.html basic-shadow-2-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-3.html basic-shadow-3-ref.html
-pref(dom.webcomponents.enabled,true) == basic-shadow-4.html basic-shadow-4-ref.html
-pref(dom.webcomponents.enabled,true) == basic-insertion-point-1.html basic-insertion-point-1-ref.html
-pref(dom.webcomponents.enabled,true) skip-if(styloVsGecko||stylo) == basic-insertion-point-2.html basic-insertion-point-2-ref.html
-pref(dom.webcomponents.enabled,true) == adjacent-insertion-points-1.html adjacent-insertion-points-1-ref.html
-pref(dom.webcomponents.enabled,true) == adjacent-insertion-points-2.html adjacent-insertion-points-2-ref.html
-pref(dom.webcomponents.enabled,true) == fallback-content-1.html fallback-content-1-ref.html
-pref(dom.webcomponents.enabled,true) == remove-insertion-point-1.html remove-insertion-point-1-ref.html
-pref(dom.webcomponents.enabled,true) == nested-insertion-point-1.html nested-insertion-point-1-ref.html
-pref(dom.webcomponents.enabled,true) skip-if(styloVsGecko||stylo) == basic-shadow-element-1.html basic-shadow-element-1-ref.html
-pref(dom.webcomponents.enabled,true) skip-if(styloVsGecko||stylo) == nested-shadow-element-1.html nested-shadow-element-1-ref.html
-pref(dom.webcomponents.enabled,true) skip-if(styloVsGecko||stylo) == update-dist-node-descendants-1.html update-dist-node-descendants-1-ref.html
-pref(dom.webcomponents.enabled,true) skip-if(styloVsGecko||stylo) == input-transition-1.html input-transition-1-ref.html
-pref(dom.webcomponents.enabled,true) == dynamic-insertion-point-distribution-1.html dynamic-insertion-point-distribution-1-ref.html
-pref(dom.webcomponents.enabled,true) == dynamic-insertion-point-distribution-2.html dynamic-insertion-point-distribution-2-ref.html
-pref(dom.webcomponents.enabled,true) == remove-append-shadow-host-1.html remove-append-shadow-host-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == cross-tree-selection-1.html cross-tree-selection-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-shadow-1.html basic-shadow-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-shadow-2.html basic-shadow-2-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-shadow-3.html basic-shadow-3-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-shadow-4.html basic-shadow-4-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-insertion-point-1.html basic-insertion-point-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-insertion-point-2.html basic-insertion-point-2-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == adjacent-insertion-points-1.html adjacent-insertion-points-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == adjacent-insertion-points-2.html adjacent-insertion-points-2-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == fallback-content-1.html fallback-content-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == remove-insertion-point-1.html remove-insertion-point-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == nested-insertion-point-1.html nested-insertion-point-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == basic-shadow-element-1.html basic-shadow-element-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == nested-shadow-element-1.html nested-shadow-element-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == update-dist-node-descendants-1.html update-dist-node-descendants-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == input-transition-1.html input-transition-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == dynamic-insertion-point-distribution-1.html dynamic-insertion-point-distribution-1-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == dynamic-insertion-point-distribution-2.html dynamic-insertion-point-distribution-2-ref.html
+pref(dom.webcomponents.enabled,true) fails-if(stylo||styloVsGecko) == remove-append-shadow-host-1.html remove-append-shadow-host-1-ref.html

layout/reftests/webcomponents/update-dist-node-descendants-1.html

@@ -5,8 +5,10 @@
 <body>
 <div id="outer"><span id="distnode">text</span></div>
 <script>
-var shadowRoot = document.getElementById('outer').createShadowRoot();
-shadowRoot.innerHTML = '<div><content></content></div>';
+function run() {
+  var shadowRoot = document.getElementById('outer').createShadowRoot();
+  shadowRoot.innerHTML = '<div><content></content></div>';
+}
 
 function tweak() {
   var distNode = document.getElementById("distnode");
@@ -15,7 +17,12 @@ function tweak() {
   document.documentElement.removeAttribute("class");
 }
 
-window.addEventListener("MozReftestInvalidate", tweak);
+if (document.body.createShadowRoot) {
+  run();
+  window.addEventListener("MozReftestInvalidate", tweak);
+} else {
+  document.documentElement.className = "";
+}
 </script>
 </body>
 </html>

layout/style/GeckoStyleContext.h

@@ -0,0 +1,192 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_GeckoStyleContext_h
+#define mozilla_GeckoStyleContext_h
+
+#include "nsStyleContext.h"
+
+namespace mozilla {
+
+class GeckoStyleContext final : public nsStyleContext {
+public:
+  GeckoStyleContext(nsStyleContext* aParent,
+                    nsIAtom* aPseudoTag,
+                    CSSPseudoElementType aPseudoType,
+                    already_AddRefed<nsRuleNode> aRuleNode,
+                    bool aSkipParentDisplayBasedStyleFixup);
+
+  void* operator new(size_t sz, nsPresContext* aPresContext);
+
+  nsPresContext* PresContext() const {
+    return RuleNode()->PresContext();
+  }
+
+  void AddChild(GeckoStyleContext* aChild);
+  void RemoveChild(GeckoStyleContext* aChild);
+
+  void* GetUniqueStyleData(const nsStyleStructID& aSID);
+  void* CreateEmptyStyleData(const nsStyleStructID& aSID);
+
+
+  /**
+   * Sets the NS_STYLE_INELIGIBLE_FOR_SHARING bit on this style context
+   * and its descendants.  If it finds a descendant that has the bit
+   * already set, assumes that it can skip that subtree.
+   */
+  void SetIneligibleForSharing();
+  /**
+   * On each descendant of this style context, clears out any cached inherited
+   * structs indicated in aStructs.
+   */
+  void ClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
+  // Find, if it already exists *and is easily findable* (i.e., near the
+  // start of the child list), a style context whose:
+  //  * GetPseudo() matches aPseudoTag
+  //  * mRuleNode matches aSource
+  //  * !!GetStyleIfVisited() == !!aSourceIfVisited, and, if they're
+  //    non-null, GetStyleIfVisited()->mRuleNode == aSourceIfVisited
+  //  * RelevantLinkVisited() == aRelevantLinkVisited
+  already_AddRefed<GeckoStyleContext>
+  FindChildWithRules(const nsIAtom* aPseudoTag,
+                     nsRuleNode* aSource,
+                     nsRuleNode* aSourceIfVisited,
+                     bool aRelevantLinkVisited);
+
+  // Tell this style context to cache aStruct as the struct for aSID
+  void SetStyle(nsStyleStructID aSID, void* aStruct);
+
+
+  /*
+   * Get the style data for a style struct.  This is the most important
+   * member function of nsStyleContext.  It fills in a const pointer
+   * to a style data struct that is appropriate for the style context's
+   * frame.  This struct may be shared with other contexts (either in
+   * the rule tree or the style context tree), so it should not be
+   * modified.
+   *
+   * This function will NOT return null (even when out of memory) when
+   * given a valid style struct ID, so the result does not need to be
+   * null-checked.
+   *
+   * The typesafe functions below are preferred to the use of this
+   * function, both because they're easier to read and because they're
+   * faster.
+   */
+  const void* NS_FASTCALL StyleData(nsStyleStructID aSID) MOZ_NONNULL_RETURN;
+
+#ifdef DEBUG
+  void ListDescendants(FILE* out, int32_t aIndent);
+
+#endif
+
+#ifdef RESTYLE_LOGGING
+
+  // This only gets called under call trees where we've already checked
+  // that PresContext()->RestyleManager()->ShouldLogRestyle() returned true.
+  // It exists here just to satisfy LOG_RESTYLE's expectations.
+  bool ShouldLogRestyle() { return true; }
+  void LogStyleContextTree(int32_t aLoggingDepth, uint32_t aStructs);
+  void LogStyleContextTree(bool aFirst, uint32_t aStructs);
+  int32_t& LoggingDepth();
+  nsCString GetCachedStyleDataAsString(uint32_t aStructs);
+#endif
+
+  // Only called for Gecko-backed nsStyleContexts.
+  void ApplyStyleFixups(bool aSkipParentDisplayBasedStyleFixup);
+
+  bool HasNoChildren() const;
+
+  nsRuleNode* RuleNode() const {
+    MOZ_ASSERT(mRuleNode);
+    return mRuleNode;
+  }
+
+  ~GeckoStyleContext() {
+    Destructor();
+  }
+
+  /**
+   * Swaps owned style struct pointers between this and aNewContext, on
+   * the assumption that aNewContext is the new style context for a frame
+   * and this is the old one.  aStructs indicates which structs to consider
+   * swapping; only those which are owned in both this and aNewContext
+   * will be swapped.
+   *
+   * Additionally, if there are identical struct pointers for one of the
+   * structs indicated by aStructs, and it is not an owned struct on this,
+   * then the cached struct slot on this will be set to null.  If the struct
+   * has been swapped on an ancestor, this style context (being the old one)
+   * will be left caching the struct pointer on the new ancestor, despite
+   * inheriting from the old ancestor.  This is not normally a problem, as
+   * this style context will usually be destroyed by being released at the
+   * end of ElementRestyler::Restyle; but for style contexts held on to outside
+   * of the frame, we need to clear out the cached pointer so that if we need
+   * it again we'll re-fetch it from the new ancestor.
+   */
+  void SwapStyleData(GeckoStyleContext* aNewContext, uint32_t aStructs);
+
+  void DestroyCachedStructs(nsPresContext* aPresContext);
+
+  /**
+   * Return style data that is currently cached on the style context.
+   * Only returns the structs we cache ourselves; never consults the
+   * rule tree.
+   *
+   * For "internal" use only in nsStyleContext and nsRuleNode.
+   */
+  const void* GetCachedStyleData(nsStyleStructID aSID)
+  {
+    const void* cachedData;
+    if (nsCachedStyleData::IsReset(aSID)) {
+      if (mCachedResetData) {
+        cachedData = mCachedResetData->mStyleStructs[aSID];
+      } else {
+        cachedData = nullptr;
+      }
+    } else {
+      cachedData = mCachedInheritedData.mStyleStructs[aSID];
+    }
+    return cachedData;
+  }
+
+  // mCachedInheritedData and mCachedResetData point to both structs that
+  // are owned by this style context and structs that are owned by one of
+  // this style context's ancestors (which are indirectly owned since this
+  // style context owns a reference to its parent).  If the bit in |mBits|
+  // is set for a struct, that means that the pointer for that struct is
+  // owned by an ancestor or by the rule node rather than by this style context.
+  // Since style contexts typically have some inherited data but only sometimes
+  // have reset data, we always allocate the mCachedInheritedData, but only
+  // sometimes allocate the mCachedResetData.
+  nsResetStyleData*       mCachedResetData; // Cached reset style data.
+  nsInheritedStyleData    mCachedInheritedData; // Cached inherited style data
+
+#ifdef DEBUG
+  void AssertStructsNotUsedElsewhere(GeckoStyleContext* aDestroyingContext,
+                                     int32_t aLevels) const;
+#endif
+
+private:
+  // Helper for ClearCachedInheritedStyleDataOnDescendants.
+  void DoClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
+
+  // Children are kept in two circularly-linked lists.  The list anchor
+  // is not part of the list (null for empty), and we point to the first
+  // child.
+  // mEmptyChild for children whose rule node is the root rule node, and
+  // mChild for other children.  The order of children is not
+  // meaningful.
+  GeckoStyleContext* mChild;
+  GeckoStyleContext* mEmptyChild;
+  GeckoStyleContext* mPrevSibling;
+  GeckoStyleContext* mNextSibling;
+  RefPtr<nsRuleNode> mRuleNode;
+
+};
+}
+
+#endif // mozilla_GeckoStyleContext_h

layout/style/ServoBindings.cpp

@@ -50,6 +50,7 @@
 #include "mozilla/EffectCompositor.h"
 #include "mozilla/EffectSet.h"
 #include "mozilla/EventStates.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/Keyframe.h"
 #include "mozilla/Mutex.h"
 #include "mozilla/ServoElementSnapshot.h"

layout/style/ServoStyleContext.cpp

@@ -0,0 +1,30 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+#include "mozilla/ServoStyleContext.h"
+
+#include "nsStyleConsts.h"
+#include "nsStyleStruct.h"
+#include "nsPresContext.h"
+
+#include "mozilla/ServoBindings.h"
+
+using namespace mozilla;
+
+ServoStyleContext::ServoStyleContext(nsStyleContext* aParent,
+                               nsPresContext* aPresContext,
+                               nsIAtom* aPseudoTag,
+                               CSSPseudoElementType aPseudoType,
+                               already_AddRefed<ServoComputedValues> aComputedValues)
+  : nsStyleContext(aParent, aPseudoTag, aPseudoType),
+  mSource(Move(aComputedValues))
+{
+  mPresContext = aPresContext;
+
+  FinishConstruction();
+
+  // No need to call ApplyStyleFixups here, since fixups are handled by Servo when
+  // producing the ServoComputedValues.
+}

layout/style/ServoStyleContext.h

@@ -0,0 +1,39 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+#ifndef mozilla_ServoStyleContext_h
+#define mozilla_ServoStyleContext_h
+
+#include "nsStyleContext.h"
+
+namespace mozilla {
+
+class ServoStyleContext final : public nsStyleContext {
+public:
+  ServoStyleContext(nsStyleContext* aParent,
+                    nsPresContext* aPresContext,
+                    nsIAtom* aPseudoTag,
+                    CSSPseudoElementType aPseudoType,
+                    already_AddRefed<ServoComputedValues> aComputedValues);
+
+  nsPresContext* PresContext() const {
+    return mPresContext;
+  }
+
+  ServoComputedValues* ComputedValues() const {
+    return mSource;
+  }
+  ~ServoStyleContext() {
+    Destructor();
+  }
+private:
+  nsPresContext* mPresContext;
+  RefPtr<ServoComputedValues> mSource;
+};
+
+}
+
+#endif // mozilla_ServoStyleContext_h

layout/style/ServoStyleRule.h

@@ -13,6 +13,7 @@
 #include "mozilla/ServoBindingTypes.h"
 
 #include "nsIDOMCSSStyleRule.h"
+#include "nsICSSStyleRuleDOMWrapper.h"
 #include "nsDOMCSSDeclaration.h"
 
 namespace mozilla {

layout/style/ServoStyleSet.cpp

@@ -441,7 +441,7 @@ ServoStyleSet::ResolveStyleForText(nsIContent* aTextNode,
   // enough to do on the main thread, which means that the parallel style system
   // can avoid worrying about text nodes.
   const ServoComputedValues* parentComputedValues =
-    aParentContext->StyleSource().AsServoComputedValues();
+    aParentContext->ComputedValues();
   RefPtr<ServoComputedValues> computedValues =
     Servo_ComputedValues_Inherit(mRawSet.get(),
                                  parentComputedValues,
@@ -457,7 +457,7 @@ already_AddRefed<nsStyleContext>
 ServoStyleSet::ResolveStyleForFirstLetterContinuation(nsStyleContext* aParentContext)
 {
   const ServoComputedValues* parent =
-    aParentContext->StyleSource().AsServoComputedValues();
+    aParentContext->ComputedValues();
   RefPtr<ServoComputedValues> computedValues =
     Servo_ComputedValues_Inherit(mRawSet.get(),
                                  parent,
@@ -571,7 +571,7 @@ ServoStyleSet::ResolveInheritingAnonymousBoxStyle(nsIAtom* aPseudoTag,
     nsCSSAnonBoxes::AnonBoxSkipsParentDisplayBasedStyleFixup(aPseudoTag);
 
   const ServoComputedValues* parentStyle =
-    aParentContext ? aParentContext->StyleSource().AsServoComputedValues()
+    aParentContext ? aParentContext->ComputedValues()
                    : nullptr;
   RefPtr<ServoComputedValues> computedValues =
     Servo_ComputedValues_GetForAnonymousBox(parentStyle, aPseudoTag, skipFixup,

layout/style/ServoUtils.h

@@ -28,12 +28,7 @@ void AssertIsMainThreadOrServoFontMetricsLocked();
   bool IsServo() const { return false; }
 #endif
 
-/**
- * Macro used in a base class of |geckotype_| and |servotype_|.
- * The class should define |StyleBackendType mType;| itself.
- */
-#define MOZ_DECL_STYLO_METHODS(geckotype_, servotype_)  \
-  MOZ_DECL_STYLO_CHECK_METHODS                          \
+#define MOZ_DECL_STYLO_CONVERT_METHODS(geckotype_, servotype_)  \
   inline geckotype_* AsGecko();                         \
   inline servotype_* AsServo();                         \
   inline const geckotype_* AsGecko() const;             \
@@ -43,6 +38,14 @@ void AssertIsMainThreadOrServoFontMetricsLocked();
   inline const geckotype_* GetAsGecko() const;          \
   inline const servotype_* GetAsServo() const;
 
+/**
+ * Macro used in a base class of |geckotype_| and |servotype_|.
+ * The class should define |StyleBackendType mType;| itself.
+ */
+#define MOZ_DECL_STYLO_METHODS(geckotype_, servotype_)  \
+  MOZ_DECL_STYLO_CHECK_METHODS                          \
+  MOZ_DECL_STYLO_CONVERT_METHODS(geckotype_, servotype_)
+
 /**
  * Macro used in inline header of class |type_| with its Gecko and Servo
  * subclasses named |geckotype_| and |servotype_| correspondingly for

layout/style/StyleAnimationValue.cpp

@@ -38,6 +38,7 @@
 #include "nsIDocument.h"
 #include "nsIFrame.h"
 #include "gfx2DGlue.h"
+#include "nsStyleContextInlines.h"
 
 using namespace mozilla;
 using namespace mozilla::css;
@@ -3519,7 +3520,7 @@ ComputeValuesFromStyleRule(nsCSSPropertyID aProperty,
 
     // Force walk of rule tree
     nsStyleStructID sid = nsCSSProps::kSIDTable[aProperty];
-    tmpStyleContext->StyleData(sid);
+    tmpStyleContext->AsGecko()->StyleData(sid);
 
     // The rule node will have unconditional cached style data if the value is
     // not context-sensitive.  So if there's nothing cached, it's not context
@@ -3970,7 +3971,7 @@ SubstitutePixelValues(nsStyleContext* aStyleContext,
   if (aInput.IsCalcUnit()) {
     RuleNodeCacheConditions conditions;
     nsRuleNode::ComputedCalc c =
-      nsRuleNode::SpecifiedCalcToComputedCalc(aInput, aStyleContext,
+      nsRuleNode::SpecifiedCalcToComputedCalc(aInput, aStyleContext->AsGecko(),
                                               aStyleContext->PresContext(),
                                               conditions);
     nsStyleCoord::CalcValue c2;
@@ -3990,7 +3991,7 @@ SubstitutePixelValues(nsStyleContext* aStyleContext,
   } else if (aInput.IsLengthUnit() &&
              aInput.GetUnit() != eCSSUnit_Pixel) {
     RuleNodeCacheConditions conditions;
-    nscoord len = nsRuleNode::CalcLength(aInput, aStyleContext,
+    nscoord len = nsRuleNode::CalcLength(aInput, aStyleContext->AsGecko(),
                                          aStyleContext->PresContext(),
                                          conditions);
     aOutput.SetFloatValue(nsPresContext::AppUnitsToFloatCSSPixels(len),
@@ -4220,7 +4221,7 @@ StyleAnimationValue::ExtractComputedValue(nsCSSPropertyID aProperty,
   MOZ_ASSERT(0 <= aProperty && aProperty < eCSSProperty_COUNT_no_shorthands,
              "bad property");
   const void* styleStruct =
-    aStyleContext->StyleData(nsCSSProps::kSIDTable[aProperty]);
+    aStyleContext->AsGecko()->StyleData(nsCSSProps::kSIDTable[aProperty]);
   ptrdiff_t ssOffset = nsCSSProps::kStyleStructOffsetTable[aProperty];
   nsStyleAnimType animType = nsCSSProps::kAnimTypeTable[aProperty];
   MOZ_ASSERT(0 <= ssOffset ||
@@ -4788,7 +4789,7 @@ StyleAnimationValue::ExtractComputedValue(nsCSSPropertyID aProperty,
           eUnit_Visibility);
         return true;
       }
-      if (aStyleContext->StyleSource().IsServoComputedValues()) {
+      if (aStyleContext->IsServo()) {
         NS_ERROR("stylo: extracting discretely animated values not supported");
         return false;
       }
@@ -5359,7 +5360,7 @@ AnimationValue::FromString(nsCSSPropertyID aProperty,
   RefPtr<nsStyleContext> styleContext =
     nsComputedDOMStyle::GetStyleContext(aElement, nullptr, shell);
 
-  if (styleContext->StyleSource().IsServoComputedValues()) {
+  if (auto servoContext = styleContext->GetAsServo()) {
     nsPresContext* presContext = shell->GetPresContext();
     if (!presContext) {
       return result;
@@ -5373,7 +5374,7 @@ AnimationValue::FromString(nsCSSPropertyID aProperty,
     }
 
     const ServoComputedValues* computedValues =
-      styleContext->StyleSource().AsServoComputedValues();
+      servoContext->ComputedValues();
     result.mServo = presContext->StyleSet()
                                ->AsServo()
                                ->ComputeAnimationValue(aElement,

layout/style/StyleContextSource.h

@@ -1,161 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* 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/. */
-
-#ifndef mozilla_StyleContextSource_h
-#define mozilla_StyleContextSource_h
-
-#include "mozilla/ServoBindingTypes.h"
-#include "nsRuleNode.h"
-
-namespace mozilla {
-
-// Tagged union between Gecko Rule Nodes and Servo Computed Values.
-//
-// The rule node is the node in the lexicographic tree of rule nodes
-// (the "rule tree") that indicates which style rules are used to
-// compute the style data, and in what cascading order.  The least
-// specific rule matched is the one whose rule node is a child of the
-// root of the rule tree, and the most specific rule matched is the
-// |mRule| member of the rule node.
-//
-// In the Servo case, we hold an atomically-refcounted handle to a
-// Servo ComputedValues struct, which is more or less the Servo equivalent
-// of an nsStyleContext.
-
-// Underlying pointer without any strong ownership semantics.
-struct NonOwningStyleContextSource
-{
-  MOZ_IMPLICIT NonOwningStyleContextSource(nsRuleNode* aRuleNode)
-    : mBits(reinterpret_cast<uintptr_t>(aRuleNode)) {}
-  explicit NonOwningStyleContextSource(const ServoComputedValues* aComputedValues)
-    : mBits(reinterpret_cast<uintptr_t>(aComputedValues) | 1) {}
-
-  bool operator==(const NonOwningStyleContextSource& aOther) const {
-    MOZ_ASSERT(IsServoComputedValues() == aOther.IsServoComputedValues(),
-               "Comparing Servo to Gecko - probably a bug");
-    return mBits == aOther.mBits;
-  }
-  bool operator!=(const NonOwningStyleContextSource& aOther) const {
-    return !(*this == aOther);
-  }
-
-  // We intentionally avoid exposing IsGeckoRuleNode() here, because that would
-  // encourage callers to do:
-  //
-  // if (source.IsGeckoRuleNode()) {
-  //   // Code that we would run unconditionally if it weren't for Servo.
-  // }
-  //
-  // We want these branches to compile away when MOZ_STYLO is disabled, but that
-  // won't happen if there's an implicit null-check.
-  bool IsNull() const { return !mBits; }
-  bool IsGeckoRuleNodeOrNull() const { return !IsServoComputedValues(); }
-  bool IsServoComputedValues() const {
-#ifdef MOZ_STYLO
-    return mBits & 1;
-#else
-    return false;
-#endif
-  }
-
-  nsRuleNode* AsGeckoRuleNode() const {
-    MOZ_ASSERT(IsGeckoRuleNodeOrNull() && !IsNull());
-    return reinterpret_cast<nsRuleNode*>(mBits);
-  }
-
-  const ServoComputedValues* AsServoComputedValues() const {
-    MOZ_ASSERT(IsServoComputedValues());
-    return reinterpret_cast<ServoComputedValues*>(mBits & ~1);
-  }
-
-  bool MatchesNoRules() const {
-    if (IsGeckoRuleNodeOrNull()) {
-      return AsGeckoRuleNode()->IsRoot();
-    }
-
-    // Just assume a Servo-backed StyleContextSource always matches some rules.
-    //
-    // MatchesNoRules is used to ensure style contexts that match no rules
-    // go into a separate mEmptyChild list on their parent.  This is only used
-    // as an optimization so that calling FindChildWithRules for style context
-    // sharing is faster for text nodes (which match no rules, and are common).
-    // Since Servo will handle sharing for us, there's no need to split children
-    // into two lists.
-    return false;
-  }
-
-private:
-  uintptr_t mBits;
-};
-
-// Higher-level struct that owns a strong reference to the source. The source
-// is never null.
-struct OwningStyleContextSource
-{
-  explicit OwningStyleContextSource(already_AddRefed<nsRuleNode> aRuleNode)
-    : mRaw(aRuleNode.take())
-  {
-    MOZ_COUNT_CTOR(OwningStyleContextSource);
-    MOZ_ASSERT(!mRaw.IsNull());
-  };
-
-  explicit OwningStyleContextSource(already_AddRefed<ServoComputedValues> aComputedValues)
-    : mRaw(aComputedValues.take())
-  {
-    MOZ_COUNT_CTOR(OwningStyleContextSource);
-    MOZ_ASSERT(!mRaw.IsNull());
-  }
-
-  OwningStyleContextSource(OwningStyleContextSource&& aOther)
-    : mRaw(aOther.mRaw)
-  {
-    MOZ_COUNT_CTOR(OwningStyleContextSource);
-    aOther.mRaw = nullptr;
-  }
-
-  OwningStyleContextSource& operator=(OwningStyleContextSource&) = delete;
-  OwningStyleContextSource(OwningStyleContextSource&) = delete;
-
-  ~OwningStyleContextSource() {
-    MOZ_COUNT_DTOR(OwningStyleContextSource);
-    if (mRaw.IsNull()) {
-      // We must have invoked the move constructor.
-    } else if (IsGeckoRuleNode()) {
-      RefPtr<nsRuleNode> releaseme = dont_AddRef(AsGeckoRuleNode());
-    } else {
-      MOZ_ASSERT(IsServoComputedValues());
-      RefPtr<ServoComputedValues> releaseme =
-        dont_AddRef(AsServoComputedValues());
-    }
-  }
-
-  bool operator==(const OwningStyleContextSource& aOther) const {
-    return mRaw == aOther.mRaw;
-  }
-  bool operator!=(const OwningStyleContextSource& aOther) const {
-    return !(*this == aOther);
-  }
-  bool IsNull() const { return mRaw.IsNull(); }
-  bool IsGeckoRuleNode() const {
-    MOZ_ASSERT(!mRaw.IsNull());
-    return mRaw.IsGeckoRuleNodeOrNull();
-  }
-  bool IsServoComputedValues() const { return mRaw.IsServoComputedValues(); }
-
-  NonOwningStyleContextSource AsRaw() const { return mRaw; }
-  nsRuleNode* AsGeckoRuleNode() const { return mRaw.AsGeckoRuleNode(); }
-  ServoComputedValues* AsServoComputedValues() const {
-    return const_cast<ServoComputedValues*>(mRaw.AsServoComputedValues());
-  }
-
-  bool MatchesNoRules() const { return mRaw.MatchesNoRules(); }
-
-private:
-  NonOwningStyleContextSource mRaw;
-};
-
-} // namespace mozilla
-
-#endif // mozilla_StyleContextSource_h

layout/style/moz.build

@@ -69,6 +69,7 @@ EXPORTS += [
     'nsStyleAutoArray.h',
     'nsStyleConsts.h',
     'nsStyleContext.h',
+    'nsStyleContextInlines.h',
     'nsStyleCoord.h',
     'nsStyleSet.h',
     'nsStyleStruct.h',
@@ -89,6 +90,7 @@ EXPORTS.mozilla += [
     'DeclarationBlock.h',
     'DeclarationBlockInlines.h',
     'DocumentStyleRootIterator.h',
+    'GeckoStyleContext.h',
     'GenericSpecifiedValues.h',
     'GenericSpecifiedValuesInlines.h',
     'HandleRefPtr.h',
@@ -116,6 +118,7 @@ EXPORTS.mozilla += [
     'ServoPageRule.h',
     'ServoPropPrefList.h',
     'ServoSpecifiedValues.h',
+    'ServoStyleContext.h',
     'ServoStyleRule.h',
     'ServoStyleSet.h',
     'ServoStyleSheet.h',
@@ -126,7 +129,6 @@ EXPORTS.mozilla += [
     'StyleAnimationValue.h',
     'StyleBackendType.h',
     'StyleComplexColor.h',
-    'StyleContextSource.h',
     'StyleSetHandle.h',
     'StyleSetHandleInlines.h',
     'StyleSheet.h',
@@ -193,6 +195,7 @@ UNIFIED_SOURCES += [
     'FontFace.cpp',
     'FontFaceSet.cpp',
     'FontFaceSetIterator.cpp',
+    'GeckoStyleContext.cpp',
     'GroupRule.cpp',
     'ImageLoader.cpp',
     'IncrementalClearCOMRuleArray.cpp',
@@ -252,6 +255,7 @@ UNIFIED_SOURCES += [
     'ServoNamespaceRule.cpp',
     'ServoPageRule.cpp',
     'ServoSpecifiedValues.cpp',
+    'ServoStyleContext.cpp',
     'ServoStyleRule.cpp',
     'ServoStyleSet.cpp',
     'ServoStyleSheet.cpp',

layout/style/nsCSSRuleProcessor.cpp

@@ -18,6 +18,7 @@
 #include "PLDHashTable.h"
 #include "nsICSSPseudoComparator.h"
 #include "mozilla/MemoryReporting.h"
+#include "mozilla/css/ImportRule.h"
 #include "mozilla/css/StyleRule.h"
 #include "mozilla/css/GroupRule.h"
 #include "nsIDocument.h"

layout/style/nsComputedDOMStyle.cpp

@@ -51,6 +51,7 @@
 #include "nsWrapperCacheInlines.h"
 #include "mozilla/AppUnits.h"
 #include <algorithm>
+#include "nsStyleContextInlines.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -563,7 +564,7 @@ MustReresolveStyle(const nsStyleContext* aContext)
 
   if (aContext->HasPseudoElementData()) {
     if (!aContext->GetPseudo() ||
-        aContext->StyleSource().IsServoComputedValues()) {
+        aContext->IsServo()) {
       // TODO(emilio): When ::first-line is supported in Servo, we may want to
       // fix this to avoid re-resolving pseudo-element styles.
       return true;
@@ -870,7 +871,7 @@ nsComputedDOMStyle::UpdateCurrentStyleSources(bool aNeedsLayoutFlush)
 
   if (!mStyleContext || MustReresolveStyle(mStyleContext)) {
 #ifdef DEBUG
-    if (mStyleContext && mStyleContext->StyleSource().IsGeckoRuleNodeOrNull()) {
+    if (mStyleContext && mStyleContext->IsGecko()) {
       // We want to check that going through this path because of
       // HasPseudoElementData is rare, because it slows us down a good
       // bit.  So check that we're really inside something associated

layout/style/nsICSSLoaderObserver.h

@@ -9,12 +9,15 @@
 #define nsICSSLoaderObserver_h___
 
 #include "nsISupports.h"
-#include "mozilla/StyleSheet.h"
 
 #define NS_ICSSLOADEROBSERVER_IID \
 { 0xf51fbf2c, 0xfe4b, 0x4a15, \
   { 0xaf, 0x7e, 0x5e, 0x20, 0x64, 0x5f, 0xaf, 0x58 } }
 
+namespace mozilla {
+  class StyleSheet;
+}
+
 class nsICSSLoaderObserver : public nsISupports {
 public:
   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ICSSLOADEROBSERVER_IID)

layout/style/nsRuleNode.cpp

@@ -39,7 +39,7 @@
 #include "nsCSSPseudoElements.h"
 #include "nsThemeConstants.h"
 #include "PLDHashTable.h"
-#include "nsStyleContext.h"
+#include "GeckoStyleContext.h"
 #include "nsStyleSet.h"
 #include "nsStyleStruct.h"
 #include "nsSize.h"
@@ -91,7 +91,7 @@ enum UnsetAction
 
 void*
 nsConditionalResetStyleData::GetConditionalStyleData(nsStyleStructID aSID,
-                               nsStyleContext* aStyleContext) const
+                               GeckoStyleContext* aStyleContext) const
 {
   Entry* e = static_cast<Entry*>(mEntries[aSID]);
   MOZ_ASSERT(e, "if mConditionalBits bit is set, we must have at least one "
@@ -145,14 +145,14 @@ CreateStyleImageRequest(nsPresContext* aPresContext, const nsCSSValue& aValue,
 static void
 SetStyleShapeSourceToCSSValue(StyleShapeSource* aShapeSource,
                               const nsCSSValue* aValue,
-                              nsStyleContext* aStyleContext,
+                              GeckoStyleContext* aStyleContext,
                               nsPresContext* aPresContext,
                               RuleNodeCacheConditions& aConditions);
 
 /* Helper function to convert a CSS <position> specified value into its
  * computed-style form. */
 static void
-ComputePositionValue(nsStyleContext* aStyleContext,
+ComputePositionValue(GeckoStyleContext* aStyleContext,
                      const nsCSSValue& aValue,
                      Position& aComputedValue,
                      RuleNodeCacheConditions& aConditions);
@@ -925,7 +925,7 @@ GetFloatFromBoxPosition(int32_t aEnumValue)
 // changes aCoord iff it returns true
 static bool SetCoord(const nsCSSValue& aValue, nsStyleCoord& aCoord,
                        const nsStyleCoord& aParentCoord,
-                       int32_t aMask, nsStyleContext* aStyleContext,
+                       int32_t aMask, GeckoStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        RuleNodeCacheConditions& aConditions)
 {
@@ -1054,7 +1054,7 @@ static inline bool SetAbsCoord(const nsCSSValue& aValue,
   // The values of the following variables will never be used; so it does not
   // matter what to set.
   const nsStyleCoord dummyParentCoord;
-  nsStyleContext* dummyStyleContext = nullptr;
+  GeckoStyleContext* dummyStyleContext = nullptr;
   nsPresContext* dummyPresContext = nullptr;
   RuleNodeCacheConditions dummyCacheKey;
 
@@ -1074,7 +1074,7 @@ static bool
 SetPairCoords(const nsCSSValue& aValue,
               nsStyleCoord& aCoordX, nsStyleCoord& aCoordY,
               const nsStyleCoord& aParentX, const nsStyleCoord& aParentY,
-              int32_t aMask, nsStyleContext* aStyleContext,
+              int32_t aMask, GeckoStyleContext* aStyleContext,
               nsPresContext* aPresContext, RuleNodeCacheConditions& aConditions)
 {
   const nsCSSValue& valX =
@@ -1233,7 +1233,7 @@ static Maybe<nscoord>
 ComputeLineWidthValue(const nsCSSValue& aValue,
                       const nscoord aParentCoord,
                       const nscoord aInitialCoord,
-                      nsStyleContext* aStyleContext,
+                      GeckoStyleContext* aStyleContext,
                       nsPresContext* aPresContext,
                       RuleNodeCacheConditions& aConditions)
 {
@@ -1269,7 +1269,7 @@ ComputeLineWidthValue(const nsCSSValue& aValue,
 }
 
 static void SetGradientCoord(const nsCSSValue& aValue, nsPresContext* aPresContext,
-                             nsStyleContext* aContext, nsStyleCoord& aResult,
+                             GeckoStyleContext* aContext, nsStyleCoord& aResult,
                              RuleNodeCacheConditions& aConditions)
 {
   // OK to pass bad aParentCoord since we're not passing SETCOORD_INHERIT
@@ -1282,7 +1282,7 @@ static void SetGradientCoord(const nsCSSValue& aValue, nsPresContext* aPresConte
 }
 
 static void SetGradient(const nsCSSValue& aValue, nsPresContext* aPresContext,
-                        nsStyleContext* aContext, nsStyleGradient& aResult,
+                        GeckoStyleContext* aContext, nsStyleGradient& aResult,
                         RuleNodeCacheConditions& aConditions)
 {
   MOZ_ASSERT(aValue.GetUnit() == eCSSUnit_Gradient,
@@ -1380,7 +1380,7 @@ static void SetGradient(const nsCSSValue& aValue, nsPresContext* aPresContext,
 }
 
 // -moz-image-rect(<uri>, <top>, <right>, <bottom>, <left>)
-static void SetStyleImageToImageRect(nsStyleContext* aStyleContext,
+static void SetStyleImageToImageRect(GeckoStyleContext* aStyleContext,
                                      const nsCSSValue& aValue,
                                      nsStyleImage& aResult)
 {
@@ -1415,7 +1415,7 @@ static void SetStyleImageToImageRect(nsStyleContext* aStyleContext,
   aResult.SetCropRect(MakeUnique<nsStyleSides>(cropRect));
 }
 
-static void SetStyleImage(nsStyleContext* aStyleContext,
+static void SetStyleImage(GeckoStyleContext* aStyleContext,
                           const nsCSSValue& aValue,
                           nsStyleImage& aResult,
                           RuleNodeCacheConditions& aConditions)
@@ -1986,15 +1986,15 @@ nsRuleNode::PropagateDependentBit(nsStyleStructID aSID, nsRuleNode* aHighestNode
 }
 
 /* static */ void
-nsRuleNode::PropagateGrandancestorBit(nsStyleContext* aContext,
-                                      nsStyleContext* aContextInheritedFrom)
+nsRuleNode::PropagateGrandancestorBit(GeckoStyleContext* aContext,
+                                      GeckoStyleContext* aContextInheritedFrom)
 {
   MOZ_ASSERT(aContext);
   MOZ_ASSERT(aContextInheritedFrom &&
              aContextInheritedFrom != aContext,
              "aContextInheritedFrom must be an ancestor of aContext");
 
-  for (nsStyleContext* context = aContext->GetParent();
+  for (GeckoStyleContext* context = aContext->GetParent();
        context != aContextInheritedFrom;
        context = context->GetParent()) {
     if (!context) {
@@ -2396,7 +2396,7 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
 // return the bit to check in nsCSSProp's flags table.  Otherwise,
 // return 0.
 inline uint32_t
-GetPseudoRestriction(nsStyleContext *aContext)
+GetPseudoRestriction(GeckoStyleContext *aContext)
 {
   // This needs to match nsStyleSet::WalkRestrictionRule.
   uint32_t pseudoRestriction = 0;
@@ -2457,7 +2457,7 @@ AutoCSSValueArray::~AutoCSSValueArray()
 /* static */ bool
 nsRuleNode::ResolveVariableReferences(const nsStyleStructID aSID,
                                       nsRuleData* aRuleData,
-                                      nsStyleContext* aContext)
+                                      GeckoStyleContext* aContext)
 {
   MOZ_ASSERT(aSID != eStyleStruct_Variables);
   MOZ_ASSERT(aRuleData->mSIDs & nsCachedStyleData::GetBitForSID(aSID));
@@ -2509,7 +2509,7 @@ nsRuleNode::ResolveVariableReferences(const nsStyleStructID aSID,
 
 const void*
 nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
-                         nsStyleContext* aContext)
+                         GeckoStyleContext* aContext)
 {
   // use placement new[] on the result of alloca() to allocate a
   // variable-sized stack array, including execution of constructors,
@@ -2689,7 +2689,7 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
     // All information must necessarily be inherited from our parent style context.
     // In the absence of any computed data in the rule tree and with
     // no rules specified that didn't have values of 'inherit', we should check our parent.
-    nsStyleContext* parentContext = aContext->GetParent();
+    GeckoStyleContext* parentContext = aContext->GetParent();
     if (isReset) {
       /* Reset structs don't inherit from first-line. */
       /* See similar code in COMPUTE_START_RESET */
@@ -2721,7 +2721,7 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
   }
 
   typedef const void* (nsRuleNode::*ComputeFunc)(void*, const nsRuleData*,
-                                                 nsStyleContext*, nsRuleNode*,
+                                                 GeckoStyleContext*, nsRuleNode*,
                                                  RuleDetail,
                                                  const RuleNodeCacheConditions);
   static const ComputeFunc sComputeFuncs[] = {
@@ -2737,7 +2737,7 @@ nsRuleNode::WalkRuleTree(const nsStyleStructID aSID,
 }
 
 const void*
-nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContext)
+nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, GeckoStyleContext* aContext)
 {
   switch (aSID) {
     case eStyleStruct_Font:
@@ -2916,7 +2916,7 @@ nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContex
   NS_ASSERTION(aRuleDetail != eRuleFullInherited,                             \
                "should not have bothered calling Compute*Data");              \
                                                                               \
-  nsStyleContext* parentContext = aContext->GetParent();                      \
+  GeckoStyleContext* parentContext = aContext->GetParent();                   \
                                                                               \
   nsStyle##type_* data_ = nullptr;                                            \
   mozilla::Maybe<nsStyle##type_> maybeFakeParentData;                         \
@@ -2976,7 +2976,7 @@ nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContex
   NS_ASSERTION(aRuleDetail != eRuleFullInherited,                             \
                "should not have bothered calling Compute*Data");              \
                                                                               \
-  nsStyleContext* parentContext = aContext->GetParent();                      \
+  GeckoStyleContext* parentContext = aContext->GetParent();                   \
   /* Reset structs don't inherit from first-line */                           \
   /* See similar code in WalkRuleTree */                                      \
   while (parentContext &&                                                     \
@@ -3304,13 +3304,13 @@ struct SetFontSizeCalcOps : public css::BasicCoordCalcOps,
   const nscoord mParentSize;
   const nsStyleFont* const mParentFont;
   nsPresContext* const mPresContext;
-  nsStyleContext* const mStyleContext;
+  GeckoStyleContext* const mStyleContext;
   const bool mAtRoot;
   RuleNodeCacheConditions& mConditions;
 
   SetFontSizeCalcOps(nscoord aParentSize, const nsStyleFont* aParentFont,
                      nsPresContext* aPresContext,
-                     nsStyleContext* aStyleContext,
+                     GeckoStyleContext* aStyleContext,
                      bool aAtRoot,
                      RuleNodeCacheConditions& aConditions)
     : mParentSize(aParentSize),
@@ -3355,7 +3355,7 @@ struct SetFontSizeCalcOps : public css::BasicCoordCalcOps,
 
 /* static */ void
 nsRuleNode::SetFontSize(nsPresContext* aPresContext,
-                        nsStyleContext* aContext,
+                        GeckoStyleContext* aContext,
                         const nsRuleData* aRuleData,
                         const nsStyleFont* aFont,
                         const nsStyleFont* aParentFont,
@@ -3534,7 +3534,7 @@ nsRuleNode::ComputeSystemFont(nsFont* aSystemFont, LookAndFeel::FontID aFontID,
 }
 
 /* static */ void
-nsRuleNode::SetFont(nsPresContext* aPresContext, nsStyleContext* aContext,
+nsRuleNode::SetFont(nsPresContext* aPresContext, GeckoStyleContext* aContext,
                     uint8_t aGenericFontID, const nsRuleData* aRuleData,
                     const nsStyleFont* aParentFont,
                     nsStyleFont* aFont, bool aUsedStartStruct,
@@ -4161,14 +4161,14 @@ nsRuleNode::ComputeFontVariations(const nsCSSValuePairList* aVariationsList,
 //  - re-apply cascading rules from there without caching intermediate values
 /* static */ void
 nsRuleNode::SetGenericFont(nsPresContext* aPresContext,
-                           nsStyleContext* aContext,
+                           GeckoStyleContext* aContext,
                            uint8_t aGenericFontID,
                            nsStyleFont* aFont)
 {
   // walk up the contexts until a context with the desired generic font
-  AutoTArray<nsStyleContext*, 8> contextPath;
+  AutoTArray<GeckoStyleContext*, 8> contextPath;
   contextPath.AppendElement(aContext);
-  nsStyleContext* higherContext = aContext->GetParent();
+  GeckoStyleContext* higherContext = aContext->GetParent();
   while (higherContext) {
     if (higherContext->StyleFont()->mGenericID == aGenericFontID) {
       // done walking up the higher contexts
@@ -4201,7 +4201,7 @@ nsRuleNode::SetGenericFont(nsPresContext* aPresContext,
   void* dataStorage = alloca(nprops * sizeof(nsCSSValue));
 
   for (int32_t i = contextPath.Length() - 1; i >= 0; --i) {
-    nsStyleContext* context = contextPath[i];
+    GeckoStyleContext* context = contextPath[i];
     AutoCSSValueArray dataArray(dataStorage, nprops);
 
     nsRuleData ruleData(NS_STYLE_INHERIT_BIT(Font), dataArray.get(),
@@ -4254,7 +4254,7 @@ nsRuleNode::SetGenericFont(nsPresContext* aPresContext,
 const void*
 nsRuleNode::ComputeFontData(void* aStartStruct,
                             const nsRuleData* aRuleData,
-                            nsStyleContext* aContext,
+                            GeckoStyleContext* aContext,
                             nsRuleNode* aHighestNode,
                             const RuleDetail aRuleDetail,
                             const RuleNodeCacheConditions aConditions)
@@ -4362,7 +4362,7 @@ inline uint32_t ListLength(const T* aList)
 
 static already_AddRefed<nsCSSShadowArray>
 GetShadowData(const nsCSSValueList* aList,
-              nsStyleContext* aContext,
+              GeckoStyleContext* aContext,
               bool aIsBoxShadow,
               nsPresContext* aPresContext,
               RuleNodeCacheConditions& aConditions)
@@ -4503,11 +4503,11 @@ struct LengthNumberCalcObj
 struct LengthNumberCalcOps : public css::FloatCoeffsAlreadyNormalizedOps
 {
   typedef LengthNumberCalcObj result_type;
-  nsStyleContext* const mStyleContext;
+  GeckoStyleContext* const mStyleContext;
   nsPresContext* const mPresContext;
   RuleNodeCacheConditions& mConditions;
 
-  LengthNumberCalcOps(nsStyleContext* aStyleContext,
+  LengthNumberCalcOps(GeckoStyleContext* aStyleContext,
                       nsPresContext* aPresContext,
                       RuleNodeCacheConditions& aConditions)
     : mStyleContext(aStyleContext),
@@ -4585,7 +4585,7 @@ struct LengthNumberCalcOps : public css::FloatCoeffsAlreadyNormalizedOps
 
 struct SetLineHeightCalcOps : public LengthNumberCalcOps
 {
-  SetLineHeightCalcOps(nsStyleContext* aStyleContext,
+  SetLineHeightCalcOps(GeckoStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        RuleNodeCacheConditions& aConditions)
     : LengthNumberCalcOps(aStyleContext, aPresContext, aConditions)
@@ -4622,7 +4622,7 @@ struct SetLineHeightCalcOps : public LengthNumberCalcOps
 const void*
 nsRuleNode::ComputeTextData(void* aStartStruct,
                             const nsRuleData* aRuleData,
-                            nsStyleContext* aContext,
+                            GeckoStyleContext* aContext,
                             nsRuleNode* aHighestNode,
                             const RuleDetail aRuleDetail,
                             const RuleNodeCacheConditions aConditions)
@@ -4748,7 +4748,7 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
              NS_STYLE_TEXT_ALIGN_MATCH_PARENT ==
                textAlignValue->GetIntValue()) {
     conditions.SetUncacheable();
-    nsStyleContext* parent = aContext->GetParent();
+    GeckoStyleContext* parent = aContext->GetParent();
     if (parent) {
       uint8_t parentAlign = parentText->mTextAlign;
       uint8_t parentDirection = parent->StyleVisibility()->mDirection;
@@ -5004,7 +5004,7 @@ nsRuleNode::ComputeTextData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeTextResetData(void* aStartStruct,
                                  const nsRuleData* aRuleData,
-                                 nsStyleContext* aContext,
+                                 GeckoStyleContext* aContext,
                                  nsRuleNode* aHighestNode,
                                  const RuleDetail aRuleDetail,
                                  const RuleNodeCacheConditions aConditions)
@@ -5143,7 +5143,7 @@ nsRuleNode::ComputeTextResetData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
                                      const nsRuleData* aRuleData,
-                                     nsStyleContext* aContext,
+                                     GeckoStyleContext* aContext,
                                      nsRuleNode* aHighestNode,
                                      const RuleDetail aRuleDetail,
                                      const RuleNodeCacheConditions aConditions)
@@ -5233,7 +5233,7 @@ nsRuleNode::ComputeUserInterfaceData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeUIResetData(void* aStartStruct,
                                const nsRuleData* aRuleData,
-                               nsStyleContext* aContext,
+                               GeckoStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const RuleNodeCacheConditions aConditions)
@@ -5487,7 +5487,7 @@ GetWillChangeBitFieldFromPropFlags(const nsCSSPropertyID& aProp)
 const void*
 nsRuleNode::ComputeDisplayData(void* aStartStruct,
                                const nsRuleData* aRuleData,
-                               nsStyleContext* aContext,
+                               GeckoStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const RuleNodeCacheConditions aConditions)
@@ -6584,7 +6584,7 @@ nsRuleNode::ComputeDisplayData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeVisibilityData(void* aStartStruct,
                                   const nsRuleData* aRuleData,
-                                  nsStyleContext* aContext,
+                                  GeckoStyleContext* aContext,
                                   nsRuleNode* aHighestNode,
                                   const RuleDetail aRuleDetail,
                                   const RuleNodeCacheConditions aConditions)
@@ -6682,7 +6682,7 @@ nsRuleNode::ComputeVisibilityData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeColorData(void* aStartStruct,
                              const nsRuleData* aRuleData,
-                             nsStyleContext* aContext,
+                             GeckoStyleContext* aContext,
                              nsRuleNode* aHighestNode,
                              const RuleDetail aRuleDetail,
                              const RuleNodeCacheConditions aConditions)
@@ -6718,7 +6718,7 @@ struct BackgroundItemComputer {
 template <>
 struct BackgroundItemComputer<nsCSSValueList, uint8_t>
 {
-  static void ComputeValue(nsStyleContext* aStyleContext,
+  static void ComputeValue(GeckoStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
                            uint8_t& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
@@ -6731,7 +6731,7 @@ struct BackgroundItemComputer<nsCSSValueList, uint8_t>
 template <>
 struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Repeat>
 {
-  static void ComputeValue(nsStyleContext* aStyleContext,
+  static void ComputeValue(GeckoStyleContext* aStyleContext,
                            const nsCSSValuePairList* aSpecifiedValue,
                            nsStyleImageLayers::Repeat& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
@@ -6792,7 +6792,7 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Repeat>
 template <>
 struct BackgroundItemComputer<nsCSSValueList, nsStyleImage>
 {
-  static void ComputeValue(nsStyleContext* aStyleContext,
+  static void ComputeValue(GeckoStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
                            nsStyleImage& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
@@ -6807,7 +6807,7 @@ struct BackgroundItemComputer<nsCSSValueList, T>
 {
   typedef typename EnableIf<IsEnum<T>::value, T>::Type ComputedType;
 
-  static void ComputeValue(nsStyleContext* aStyleContext,
+  static void ComputeValue(GeckoStyleContext* aStyleContext,
                            const nsCSSValueList* aSpecifiedValue,
                            ComputedType& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
@@ -6822,7 +6822,7 @@ struct BackgroundItemComputer<nsCSSValueList, T>
  * which represent an edge and an offset from that edge.
  */
 static void
-ComputePositionCoord(nsStyleContext* aStyleContext,
+ComputePositionCoord(GeckoStyleContext* aStyleContext,
                      const nsCSSValue& aEdge,
                      const nsCSSValue& aOffset,
                      Position::Coord* aResult,
@@ -6873,7 +6873,7 @@ ComputePositionCoord(nsStyleContext* aStyleContext,
 /* Helper function to convert a CSS <position> specified value into its
  * computed-style form. */
 static void
-ComputePositionValue(nsStyleContext* aStyleContext,
+ComputePositionValue(GeckoStyleContext* aStyleContext,
                      const nsCSSValue& aValue,
                      Position& aComputedValue,
                      RuleNodeCacheConditions& aConditions)
@@ -6910,7 +6910,7 @@ ComputePositionValue(nsStyleContext* aStyleContext,
 /* Helper function to convert the -x or -y part of a CSS <position> specified
  * value into its computed-style form. */
 static void
-ComputePositionCoordValue(nsStyleContext* aStyleContext,
+ComputePositionCoordValue(GeckoStyleContext* aStyleContext,
                           const nsCSSValue& aValue,
                           Position::Coord& aComputedValue,
                           RuleNodeCacheConditions& aConditions)
@@ -6953,7 +6953,7 @@ static const BackgroundSizeAxis gBGSizeAxes[] = {
 template <>
 struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Size>
 {
-  static void ComputeValue(nsStyleContext* aStyleContext,
+  static void ComputeValue(GeckoStyleContext* aStyleContext,
                            const nsCSSValuePairList* aSpecifiedValue,
                            nsStyleImageLayers::Size& aComputedValue,
                            RuleNodeCacheConditions& aConditions)
@@ -7036,7 +7036,7 @@ struct BackgroundItemComputer<nsCSSValuePairList, nsStyleImageLayers::Size>
 
 template <class ComputedValueItem>
 static void
-SetImageLayerList(nsStyleContext* aStyleContext,
+SetImageLayerList(GeckoStyleContext* aStyleContext,
                   const nsCSSValue& aValue,
                   nsStyleAutoArray<nsStyleImageLayers::Layer>& aLayers,
                   const nsStyleAutoArray<nsStyleImageLayers::Layer>& aParentLayers,
@@ -7105,7 +7105,7 @@ SetImageLayerList(nsStyleContext* aStyleContext,
 // SetImageLayerList generic enough to handle both cases.
 static void
 SetImageLayerPositionCoordList(
-                  nsStyleContext* aStyleContext,
+                  GeckoStyleContext* aStyleContext,
                   const nsCSSValue& aValue,
                   nsStyleAutoArray<nsStyleImageLayers::Layer>& aLayers,
                   const nsStyleAutoArray<nsStyleImageLayers::Layer>& aParentLayers,
@@ -7171,7 +7171,7 @@ SetImageLayerPositionCoordList(
 
 template <class ComputedValueItem>
 static void
-SetImageLayerPairList(nsStyleContext* aStyleContext,
+SetImageLayerPairList(GeckoStyleContext* aStyleContext,
                       const nsCSSValue& aValue,
                       nsStyleAutoArray<nsStyleImageLayers::Layer>& aLayers,
                       const nsStyleAutoArray<nsStyleImageLayers::Layer>& aParentLayers,
@@ -7319,7 +7319,7 @@ nsRuleNode::FillAllBackgroundLists(nsStyleImageLayers& aImage,
 const void*
 nsRuleNode::ComputeBackgroundData(void* aStartStruct,
                                   const nsRuleData* aRuleData,
-                                  nsStyleContext* aContext,
+                                  GeckoStyleContext* aContext,
                                   nsRuleNode* aHighestNode,
                                   const RuleDetail aRuleDetail,
                                   const RuleNodeCacheConditions aConditions)
@@ -7440,7 +7440,7 @@ nsRuleNode::ComputeBackgroundData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeMarginData(void* aStartStruct,
                               const nsRuleData* aRuleData,
-                              nsStyleContext* aContext,
+                              GeckoStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const RuleNodeCacheConditions aConditions)
@@ -7545,7 +7545,7 @@ SetBorderImageSlice(const nsCSSValue& aValue,
 const void*
 nsRuleNode::ComputeBorderData(void* aStartStruct,
                               const nsRuleData* aRuleData,
-                              nsStyleContext* aContext,
+                              GeckoStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const RuleNodeCacheConditions aConditions)
@@ -7804,7 +7804,7 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
 const void*
 nsRuleNode::ComputePaddingData(void* aStartStruct,
                                const nsRuleData* aRuleData,
-                               nsStyleContext* aContext,
+                               GeckoStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const RuleNodeCacheConditions aConditions)
@@ -7832,7 +7832,7 @@ nsRuleNode::ComputePaddingData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeOutlineData(void* aStartStruct,
                                const nsRuleData* aRuleData,
-                               nsStyleContext* aContext,
+                               GeckoStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const RuleNodeCacheConditions aConditions)
@@ -7916,7 +7916,7 @@ nsRuleNode::ComputeOutlineData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeListData(void* aStartStruct,
                             const nsRuleData* aRuleData,
-                            nsStyleContext* aContext,
+                            GeckoStyleContext* aContext,
                             nsRuleNode* aHighestNode,
                             const RuleDetail aRuleDetail,
                             const RuleNodeCacheConditions aConditions)
@@ -8107,7 +8107,7 @@ nsRuleNode::ComputeListData(void* aStartStruct,
 static void
 SetGridTrackBreadth(const nsCSSValue& aValue,
                     nsStyleCoord& aResult,
-                    nsStyleContext* aStyleContext,
+                    GeckoStyleContext* aStyleContext,
                     nsPresContext* aPresContext,
                     RuleNodeCacheConditions& aConditions)
 {
@@ -8135,7 +8135,7 @@ static void
 SetGridTrackSize(const nsCSSValue& aValue,
                  nsStyleCoord& aResultMin,
                  nsStyleCoord& aResultMax,
-                 nsStyleContext* aStyleContext,
+                 GeckoStyleContext* aStyleContext,
                  nsPresContext* aPresContext,
                  RuleNodeCacheConditions& aConditions)
 {
@@ -8171,7 +8171,7 @@ SetGridAutoColumnsRows(const nsCSSValue& aValue,
                        nsStyleCoord& aResultMax,
                        const nsStyleCoord& aParentValueMin,
                        const nsStyleCoord& aParentValueMax,
-                       nsStyleContext* aStyleContext,
+                       GeckoStyleContext* aStyleContext,
                        nsPresContext* aPresContext,
                        RuleNodeCacheConditions& aConditions)
 
@@ -8221,7 +8221,7 @@ static void
 SetGridTrackList(const nsCSSValue& aValue,
                  nsStyleGridTemplate& aResult,
                  const nsStyleGridTemplate& aParentValue,
-                 nsStyleContext* aStyleContext,
+                 GeckoStyleContext* aStyleContext,
                  nsPresContext* aPresContext,
                  RuleNodeCacheConditions& aConditions)
 
@@ -8413,7 +8413,7 @@ SetGridLine(const nsCSSValue& aValue,
 const void*
 nsRuleNode::ComputePositionData(void* aStartStruct,
                                 const nsRuleData* aRuleData,
-                                nsStyleContext* aContext,
+                                GeckoStyleContext* aContext,
                                 nsRuleNode* aHighestNode,
                                 const RuleDetail aRuleDetail,
                                 const RuleNodeCacheConditions aConditions)
@@ -8756,7 +8756,7 @@ nsRuleNode::ComputePositionData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeTableData(void* aStartStruct,
                              const nsRuleData* aRuleData,
-                             nsStyleContext* aContext,
+                             GeckoStyleContext* aContext,
                              nsRuleNode* aHighestNode,
                              const RuleDetail aRuleDetail,
                              const RuleNodeCacheConditions aConditions)
@@ -8782,7 +8782,7 @@ nsRuleNode::ComputeTableData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeTableBorderData(void* aStartStruct,
                                    const nsRuleData* aRuleData,
-                                   nsStyleContext* aContext,
+                                   GeckoStyleContext* aContext,
                                    nsRuleNode* aHighestNode,
                                    const RuleDetail aRuleDetail,
                                    const RuleNodeCacheConditions aConditions)
@@ -8839,7 +8839,7 @@ nsRuleNode::ComputeTableBorderData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeContentData(void* aStartStruct,
                                const nsRuleData* aRuleData,
-                               nsStyleContext* aContext,
+                               GeckoStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const RuleNodeCacheConditions aConditions)
@@ -9062,7 +9062,7 @@ nsRuleNode::ComputeContentData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeXULData(void* aStartStruct,
                            const nsRuleData* aRuleData,
-                           nsStyleContext* aContext,
+                           GeckoStyleContext* aContext,
                            nsRuleNode* aHighestNode,
                            const RuleDetail aRuleDetail,
                            const RuleNodeCacheConditions aConditions)
@@ -9121,7 +9121,7 @@ nsRuleNode::ComputeXULData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeColumnData(void* aStartStruct,
                               const nsRuleData* aRuleData,
-                              nsStyleContext* aContext,
+                              GeckoStyleContext* aContext,
                               nsRuleNode* aHighestNode,
                               const RuleDetail aRuleDetail,
                               const RuleNodeCacheConditions aConditions)
@@ -9217,7 +9217,7 @@ nsRuleNode::ComputeColumnData(void* aStartStruct,
 
 static void
 SetSVGPaint(const nsCSSValue& aValue, const nsStyleSVGPaint& parentPaint,
-            nsPresContext* aPresContext, nsStyleContext *aContext,
+            nsPresContext* aPresContext, GeckoStyleContext *aContext,
             nsStyleSVGPaint& aResult, nsStyleSVGPaintType aInitialPaintType,
             RuleNodeCacheConditions& aConditions)
 {
@@ -9376,7 +9376,7 @@ nsRuleNode::FillAllMaskLists(nsStyleImageLayers& aMask,
 const void*
 nsRuleNode::ComputeSVGData(void* aStartStruct,
                            const nsRuleData* aRuleData,
-                           nsStyleContext* aContext,
+                           GeckoStyleContext* aContext,
                            nsRuleNode* aHighestNode,
                            const RuleDetail aRuleDetail,
                            const RuleNodeCacheConditions aConditions)
@@ -9682,7 +9682,7 @@ nsRuleNode::ComputeSVGData(void* aStartStruct,
 
 static already_AddRefed<StyleBasicShape>
 GetStyleBasicShapeFromCSSValue(const nsCSSValue& aValue,
-                               nsStyleContext* aStyleContext,
+                               GeckoStyleContext* aStyleContext,
                                nsPresContext* aPresContext,
                                RuleNodeCacheConditions& aConditions)
 {
@@ -9835,7 +9835,7 @@ static void
 SetStyleShapeSourceToCSSValue(
   StyleShapeSource* aShapeSource,
   const nsCSSValue* aValue,
-  nsStyleContext* aStyleContext,
+  GeckoStyleContext* aStyleContext,
   nsPresContext* aPresContext,
   RuleNodeCacheConditions& aConditions)
 {
@@ -9873,7 +9873,7 @@ SetStyleShapeSourceToCSSValue(
 static bool
 SetStyleFilterToCSSValue(nsStyleFilter* aStyleFilter,
                          const nsCSSValue& aValue,
-                         nsStyleContext* aStyleContext,
+                         GeckoStyleContext* aStyleContext,
                          nsPresContext* aPresContext,
                          RuleNodeCacheConditions& aConditions)
 {
@@ -9931,7 +9931,7 @@ SetStyleFilterToCSSValue(nsStyleFilter* aStyleFilter,
 const void*
 nsRuleNode::ComputeSVGResetData(void* aStartStruct,
                                 const nsRuleData* aRuleData,
-                                nsStyleContext* aContext,
+                                GeckoStyleContext* aContext,
                                 nsRuleNode* aHighestNode,
                                 const RuleDetail aRuleDetail,
                                 const RuleNodeCacheConditions aConditions)
@@ -10156,7 +10156,7 @@ nsRuleNode::ComputeSVGResetData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeVariablesData(void* aStartStruct,
                                  const nsRuleData* aRuleData,
-                                 nsStyleContext* aContext,
+                                 GeckoStyleContext* aContext,
                                  nsRuleNode* aHighestNode,
                                  const RuleDetail aRuleDetail,
                                  const RuleNodeCacheConditions aConditions)
@@ -10178,7 +10178,7 @@ nsRuleNode::ComputeVariablesData(void* aStartStruct,
 const void*
 nsRuleNode::ComputeEffectsData(void* aStartStruct,
                                const nsRuleData* aRuleData,
-                               nsStyleContext* aContext,
+                               GeckoStyleContext* aContext,
                                nsRuleNode* aHighestNode,
                                const RuleDetail aRuleDetail,
                                const RuleNodeCacheConditions aConditions)
@@ -10338,7 +10338,7 @@ nsRuleNode::ComputeEffectsData(void* aStartStruct,
 
 const void*
 nsRuleNode::GetStyleData(nsStyleStructID aSID,
-                         nsStyleContext* aContext,
+                         GeckoStyleContext* aContext,
                          bool aComputeData)
 {
   NS_ASSERTION(IsUsedDirectly(),
@@ -10401,12 +10401,14 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
                                     bool aAuthorColorsAllowed)
 {
 #ifdef MOZ_STYLO
-  if (aStyleContext->StyleSource().IsServoComputedValues()) {
+  if (aStyleContext->IsServo()) {
     NS_WARNING("stylo: nsRuleNode::HasAuthorSpecifiedRules not implemented");
     return true;
   }
 #endif
 
+  RefPtr<GeckoStyleContext> styleContext = aStyleContext->AsGecko();
+
   uint32_t inheritBits = 0;
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND)
     inheritBits |= NS_STYLE_INHERIT_BIT(Background);
@@ -10452,9 +10454,9 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
   void* dataStorage = alloca(nprops * sizeof(nsCSSValue));
   AutoCSSValueArray dataArray(dataStorage, nprops);
 
-  /* We're relying on the use of |aStyleContext| not mutating it! */
+  /* We're relying on the use of |styleContext| not mutating it! */
   nsRuleData ruleData(inheritBits, dataArray.get(),
-                      aStyleContext->PresContext(), aStyleContext);
+                      styleContext->PresContext(), styleContext);
 
   if (ruleTypeMask & NS_AUTHOR_SPECIFIED_BACKGROUND) {
     ruleData.mValueOffsets[eStyleStruct_Background] = backgroundOffset;
@@ -10552,7 +10554,7 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
     }
   }
 
-  nsStyleContext* styleContext = aStyleContext;
+  GeckoStyleContext* styleContextRef = styleContext;
 
   // We need to be careful not to count styles covered up by user-important or
   // UA-important declarations.  But we do want to catch explicit inherit
@@ -10563,7 +10565,7 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
   bool haveExplicitUAInherit;
   do {
     haveExplicitUAInherit = false;
-    for (nsRuleNode* ruleNode = styleContext->RuleNode(); ruleNode;
+    for (nsRuleNode* ruleNode = styleContextRef->RuleNode(); ruleNode;
          ruleNode = ruleNode->GetParent()) {
       nsIStyleRule *rule = ruleNode->GetRule();
       if (rule) {
@@ -10630,7 +10632,7 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
       for (uint32_t i = 0; i < nValues; ++i)
         if (values[i]->GetUnit() == eCSSUnit_DummyInherit)
           values[i]->Reset();
-      styleContext = styleContext->GetParent();
+      styleContextRef = styleContextRef->GetParent();
     }
   } while (haveExplicitUAInherit && styleContext);
 
@@ -10640,7 +10642,7 @@ nsRuleNode::HasAuthorSpecifiedRules(nsStyleContext* aStyleContext,
 /* static */ void
 nsRuleNode::ComputePropertiesOverridingAnimation(
                               const nsTArray<nsCSSPropertyID>& aProperties,
-                              nsStyleContext* aStyleContext,
+                              GeckoStyleContext* aStyleContext,
                               nsCSSPropertyIDSet& aPropertiesOverridden)
 {
   /*
@@ -10740,14 +10742,14 @@ nsRuleNode::ComputeColor(const nsCSSValue& aValue, nsPresContext* aPresContext,
 }
 
 /* static */ bool
-nsRuleNode::ParentHasPseudoElementData(nsStyleContext* aContext)
+nsRuleNode::ParentHasPseudoElementData(GeckoStyleContext* aContext)
 {
-  nsStyleContext* parent = aContext->GetParent();
+  GeckoStyleContext* parent = aContext->GetParent();
   return parent && parent->HasPseudoElementData();
 }
 
 /* static */ void
-nsRuleNode::StoreStyleOnContext(nsStyleContext* aContext,
+nsRuleNode::StoreStyleOnContext(GeckoStyleContext* aContext,
                                 nsStyleStructID aSID,
                                 void* aStruct)
 {
@@ -10757,7 +10759,7 @@ nsRuleNode::StoreStyleOnContext(nsStyleContext* aContext,
 
 #ifdef DEBUG
 bool
-nsRuleNode::ContextHasCachedData(nsStyleContext* aContext,
+nsRuleNode::ContextHasCachedData(GeckoStyleContext* aContext,
                                  nsStyleStructID aSID)
 {
   return !!aContext->GetCachedStyleData(aSID);

layout/style/nsRuleNode.h

@@ -25,13 +25,16 @@ class nsCSSPropertyIDSet;
 class nsCSSValue;
 class nsFontMetrics;
 class nsIStyleRule;
-class nsStyleContext;
 class nsStyleCoord;
 struct nsCSSRect;
 struct nsCSSValueList;
 struct nsCSSValuePairList;
 struct nsRuleData;
 
+namespace mozilla {
+  class GeckoStyleContext;
+}
+
 struct nsInheritedStyleData
 {
   mozilla::RangedArray<void*,
@@ -163,7 +166,7 @@ struct nsConditionalResetStyleData
   }
 
   void* GetStyleData(nsStyleStructID aSID,
-                     nsStyleContext* aStyleContext,
+                     mozilla::GeckoStyleContext* aStyleContext,
                      bool aCanComputeData) const {
     if (!(mConditionalBits & GetBitForSID(aSID))) {
       return mEntries[aSID];
@@ -183,7 +186,7 @@ struct nsConditionalResetStyleData
 private:
   // non-inline helper for GetStyleData
   void* GetConditionalStyleData(nsStyleStructID aSID,
-                                nsStyleContext* aStyleContext) const;
+                                mozilla::GeckoStyleContext* aStyleContext) const;
 
 public:
   void SetStyleData(nsStyleStructID aSID, void* aStyleStruct) {
@@ -284,7 +287,7 @@ struct nsCachedStyleData
   }
 
   void* NS_FASTCALL GetStyleData(const nsStyleStructID aSID,
-                                 nsStyleContext* aStyleContext,
+                                 mozilla::GeckoStyleContext* aStyleContext,
                                  bool aCanComputeData) {
     if (IsReset(aSID)) {
       if (mResetData) {
@@ -320,7 +323,7 @@ struct nsCachedStyleData
         mInheritedData->mStyleStructs[eStyleStruct_##name_]) : nullptr;        \
     }
   #define STYLE_STRUCT_RESET(name_, checkdata_cb_)                             \
-    nsStyle##name_ * NS_FASTCALL GetStyle##name_ (nsStyleContext* aContext,    \
+    nsStyle##name_ * NS_FASTCALL GetStyle##name_ (mozilla::GeckoStyleContext* aContext,    \
                                                   bool aCanComputeData) {      \
       return mResetData ? static_cast<nsStyle##name_*>(                        \
         mResetData->GetStyleData(eStyleStruct_##name_, aContext,               \
@@ -355,9 +358,9 @@ struct nsCachedStyleData
  * destroyed when their reference-count drops to zero, but are instead
  * destroyed during a GC sweep.
  *
- * An nsStyleContext, which represents the computed style data for an
+ * An mozilla::GeckoStyleContext, which represents the computed style data for an
  * element, points to an nsRuleNode.  The path from the root of the rule
- * tree to the nsStyleContext's mRuleNode gives the list of the rules
+ * tree to the mozilla::GeckoStyleContext's mRuleNode gives the list of the rules
  * matched, from least important in the cascading order to most
  * important in the cascading order.
  *
@@ -374,14 +377,14 @@ struct nsCachedStyleData
  *   1. [mainly reset structs] When a style data struct will contain the
  *      same computed value for any elements that match the same set of
  *      rules (common for reset structs), it can be stored on the
- *      nsRuleNode instead of on the nsStyleContext.
+ *      nsRuleNode instead of on the mozilla::GeckoStyleContext.
  *   2. [only? reset structs] When (1) occurs, and an nsRuleNode doesn't
  *      have any rules that change the values in the struct, the
  *      nsRuleNode can share that struct with its parent nsRuleNode.
  *   3. [mainly inherited structs] When an element doesn't match any
  *      rules that change the value of a property (or, in the edge case,
- *      when all the values specified are 'inherit'), the nsStyleContext
- *      can use the same nsStyle* struct as its parent nsStyleContext.
+ *      when all the values specified are 'inherit'), the mozilla::GeckoStyleContext
+ *      can use the same nsStyle* struct as its parent mozilla::GeckoStyleContext.
  *
  * Since the data represented by an nsIStyleRule are immutable, the data
  * represented by an nsRuleNode are also immutable.
@@ -565,11 +568,11 @@ protected:
   void PropagateDependentBit(nsStyleStructID aSID, nsRuleNode* aHighestNode,
                              void* aStruct);
   void PropagateNoneBit(uint32_t aBit, nsRuleNode* aHighestNode);
-  static void PropagateGrandancestorBit(nsStyleContext* aContext,
-                                        nsStyleContext* aContextInheritedFrom);
+  static void PropagateGrandancestorBit(mozilla::GeckoStyleContext* aContext,
+                                        mozilla::GeckoStyleContext* aContextInheritedFrom);
 
   const void* SetDefaultOnRoot(const nsStyleStructID aSID,
-                               nsStyleContext* aContext);
+                               mozilla::GeckoStyleContext* aContext);
 
   /**
    * Resolves any property values in aRuleData for a given style struct that
@@ -581,127 +584,127 @@ protected:
    */
   static bool ResolveVariableReferences(const nsStyleStructID aSID,
                                         nsRuleData* aRuleData,
-                                        nsStyleContext* aContext);
+                                        mozilla::GeckoStyleContext* aContext);
 
   const void*
-    WalkRuleTree(const nsStyleStructID aSID, nsStyleContext* aContext);
+    WalkRuleTree(const nsStyleStructID aSID, mozilla::GeckoStyleContext* aContext);
 
   const void*
     ComputeDisplayData(void* aStartStruct,
                        const nsRuleData* aRuleData,
-                       nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                       mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                        RuleDetail aRuleDetail,
                        const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeVisibilityData(void* aStartStruct,
                           const nsRuleData* aRuleData,
-                          nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                          mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                           RuleDetail aRuleDetail,
                           const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeFontData(void* aStartStruct,
                     const nsRuleData* aRuleData,
-                    nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                    mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                     RuleDetail aRuleDetail,
                     const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeColorData(void* aStartStruct,
                      const nsRuleData* aRuleData,
-                     nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                     mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                      RuleDetail aRuleDetail,
                      const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeBackgroundData(void* aStartStruct,
                           const nsRuleData* aRuleData,
-                          nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                          mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                           RuleDetail aRuleDetail,
                           const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeMarginData(void* aStartStruct,
                       const nsRuleData* aRuleData,
-                      nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                      mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                       RuleDetail aRuleDetail,
                       const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeBorderData(void* aStartStruct,
                       const nsRuleData* aRuleData,
-                      nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                      mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                       RuleDetail aRuleDetail,
                       const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputePaddingData(void* aStartStruct,
                        const nsRuleData* aRuleData,
-                       nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                       mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                        RuleDetail aRuleDetail,
                        const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeOutlineData(void* aStartStruct,
                        const nsRuleData* aRuleData,
-                       nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                       mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                        RuleDetail aRuleDetail,
                        const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeListData(void* aStartStruct,
                     const nsRuleData* aRuleData,
-                    nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                    mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                     RuleDetail aRuleDetail,
                     const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputePositionData(void* aStartStruct,
                         const nsRuleData* aRuleData,
-                        nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                        mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                         RuleDetail aRuleDetail,
                         const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeTableData(void* aStartStruct,
                      const nsRuleData* aRuleData,
-                     nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                     mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                      RuleDetail aRuleDetail,
                      const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeTableBorderData(void* aStartStruct,
                            const nsRuleData* aRuleData,
-                           nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                           mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                            RuleDetail aRuleDetail,
                            const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeContentData(void* aStartStruct,
                        const nsRuleData* aRuleData,
-                       nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                       mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                        RuleDetail aRuleDetail,
                        const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeTextData(void* aStartStruct,
                     const nsRuleData* aRuleData,
-                    nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                    mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                     RuleDetail aRuleDetail,
                     const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeTextResetData(void* aStartStruct,
                          const nsRuleData* aRuleData,
-                         nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                         mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                          RuleDetail aRuleDetail,
                          const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeUserInterfaceData(void* aStartStruct,
                              const nsRuleData* aRuleData,
-                             nsStyleContext* aContext,
+                             mozilla::GeckoStyleContext* aContext,
                              nsRuleNode* aHighestNode,
                              RuleDetail aRuleDetail,
                              const mozilla::RuleNodeCacheConditions aConditions);
@@ -709,55 +712,55 @@ protected:
   const void*
     ComputeUIResetData(void* aStartStruct,
                        const nsRuleData* aRuleData,
-                       nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                       mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                        RuleDetail aRuleDetail,
                        const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeXULData(void* aStartStruct,
                    const nsRuleData* aRuleData,
-                   nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                   mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                    RuleDetail aRuleDetail,
                    const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeColumnData(void* aStartStruct,
                       const nsRuleData* aRuleData,
-                      nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                      mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                       RuleDetail aRuleDetail,
                       const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeSVGData(void* aStartStruct,
                    const nsRuleData* aRuleData,
-                   nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                   mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                    RuleDetail aRuleDetail,
                    const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeSVGResetData(void* aStartStruct,
                         const nsRuleData* aRuleData,
-                        nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                        mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                         RuleDetail aRuleDetail,
                         const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeVariablesData(void* aStartStruct,
                          const nsRuleData* aRuleData,
-                         nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                         mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                          RuleDetail aRuleDetail,
                          const mozilla::RuleNodeCacheConditions aConditions);
 
   const void*
     ComputeEffectsData(void* aStartStruct,
                        const nsRuleData* aRuleData,
-                       nsStyleContext* aContext, nsRuleNode* aHighestNode,
+                       mozilla::GeckoStyleContext* aContext, nsRuleNode* aHighestNode,
                        RuleDetail aRuleDetail,
                        const mozilla::RuleNodeCacheConditions aConditions);
 
   // helpers for |ComputeFontData| that need access to |mNoneBits|:
   static void SetFontSize(nsPresContext* aPresContext,
-                          nsStyleContext* aContext,
+                          mozilla::GeckoStyleContext* aContext,
                           const nsRuleData* aRuleData,
                           const nsStyleFont* aFont,
                           const nsStyleFont* aParentFont,
@@ -770,7 +773,7 @@ protected:
                           mozilla::RuleNodeCacheConditions& aConditions);
 
   static void SetFont(nsPresContext* aPresContext,
-                      nsStyleContext* aContext,
+                      mozilla::GeckoStyleContext* aContext,
                       uint8_t aGenericFontID,
                       const nsRuleData* aRuleData,
                       const nsStyleFont* aParentFont,
@@ -779,7 +782,7 @@ protected:
                       mozilla::RuleNodeCacheConditions& aConditions);
 
   static void SetGenericFont(nsPresContext* aPresContext,
-                             nsStyleContext* aContext,
+                             mozilla::GeckoStyleContext* aContext,
                              uint8_t aGenericFontID,
                              nsStyleFont* aFont);
 
@@ -890,7 +893,7 @@ public:
   nsPresContext* PresContext() const { return mPresContext; }
 
   const void* GetStyleData(nsStyleStructID aSID,
-                           nsStyleContext* aContext,
+                           mozilla::GeckoStyleContext* aContext,
                            bool aComputeData);
 
   void GetDiscretelyAnimatedCSSValue(nsCSSPropertyID aProperty,
@@ -901,7 +904,7 @@ public:
   #define STYLE_STRUCT_INHERITED(name_, checkdata_cb_)                        \
   template<bool aComputeData>                                                 \
   const nsStyle##name_*                                                       \
-  GetStyle##name_(nsStyleContext* aContext, uint64_t& aContextStyleBits)      \
+  GetStyle##name_(mozilla::GeckoStyleContext* aContext, uint64_t& aContextStyleBits)      \
   {                                                                           \
     NS_ASSERTION(IsUsedDirectly(),                                            \
                  "if we ever call this on rule nodes that aren't used "       \
@@ -940,7 +943,7 @@ public:
   #define STYLE_STRUCT_RESET(name_, checkdata_cb_)                            \
   template<bool aComputeData>                                                 \
   const nsStyle##name_*                                                       \
-  GetStyle##name_(nsStyleContext* aContext)                                   \
+  GetStyle##name_(mozilla::GeckoStyleContext* aContext)                                   \
   {                                                                           \
     NS_ASSERTION(IsUsedDirectly(),                                            \
                  "if we ever call this on rule nodes that aren't used "       \
@@ -996,7 +999,7 @@ public:
   static void
   ComputePropertiesOverridingAnimation(
                               const nsTArray<nsCSSPropertyID>& aProperties,
-                              nsStyleContext* aStyleContext,
+                              mozilla::GeckoStyleContext* aStyleContext,
                               nsCSSPropertyIDSet& aPropertiesOverridden);
 
   // Expose this so media queries can use it
@@ -1091,7 +1094,7 @@ public:
                            nsStyleContext* aStyleContext,
                            nscolor& aResult);
 
-  static bool ParentHasPseudoElementData(nsStyleContext* aContext);
+  static bool ParentHasPseudoElementData(mozilla::GeckoStyleContext* aContext);
 
   static void ComputeTimingFunction(const nsCSSValue& aValue,
                                     nsTimingFunction& aResult);
@@ -1113,12 +1116,12 @@ private:
 #ifdef DEBUG
   // non-inline helper function to allow assertions without incomplete
   // type errors
-  bool ContextHasCachedData(nsStyleContext* aContext, nsStyleStructID aSID);
+  bool ContextHasCachedData(mozilla::GeckoStyleContext* aContext, nsStyleStructID aSID);
 #endif
 
   // Store style struct on the style context and tell the style context
   // that it doesn't own the data
-  static void StoreStyleOnContext(nsStyleContext* aContext,
+  static void StoreStyleOnContext(mozilla::GeckoStyleContext* aContext,
                                   nsStyleStructID aSID,
                                   void* aStruct);
 };

layout/style/nsStyleContext.h

@@ -11,7 +11,7 @@
 #include "mozilla/Assertions.h"
 #include "mozilla/RestyleLogging.h"
 #include "mozilla/ServoStyleSet.h"
-#include "mozilla/StyleContextSource.h"
+#include "mozilla/ServoUtils.h"
 #include "mozilla/StyleComplexColor.h"
 #include "nsCSSAnonBoxes.h"
 #include "nsStyleSet.h"
@@ -21,6 +21,8 @@ class nsPresContext;
 
 namespace mozilla {
 enum class CSSPseudoElementType : uint8_t;
+class GeckoStyleContext;
+class ServoStyleContext;
 } // namespace mozilla
 
 extern "C" {
@@ -52,53 +54,24 @@ extern "C" {
  *     expectation, but it makes sense in this case)
  */
 
-class nsStyleContext final
+class nsStyleContext
 {
 public:
-  /**
-   * Create a new style context.
-   * @param aParent  The parent of a style context is used for CSS
-   *                 inheritance.  When the element or pseudo-element
-   *                 this style context represents the style data of
-   *                 inherits a CSS property, the value comes from the
-   *                 parent style context.  This means style context
-   *                 parentage must match the definitions of inheritance
-   *                 in the CSS specification.
-   * @param aPseudoTag  The pseudo-element or anonymous box for which
-   *                    this style context represents style.  Null if
-   *                    this style context is for a normal DOM element.
-   * @param aPseudoType  Must match aPseudoTag.
-   * @param aRuleNode  A rule node representing the ordered sequence of
-   *                   rules that any element, pseudo-element, or
-   *                   anonymous box that this style context is for
-   *                   matches.  See |nsRuleNode| and |nsIStyleRule|.
-   * @param aSkipParentDisplayBasedStyleFixup
-   *                 If set, this flag indicates that we should skip
-   *                 the chunk of ApplyStyleFixups() that applies to
-   *                 special cases where a child element's style may
-   *                 need to be modified based on its parent's display
-   *                 value.
-   */
-  nsStyleContext(nsStyleContext* aParent, nsIAtom* aPseudoTag,
-                 mozilla::CSSPseudoElementType aPseudoType,
-                 already_AddRefed<nsRuleNode> aRuleNode,
-                 bool aSkipParentDisplayBasedStyleFixup);
+#ifdef MOZ_STYLO
+  bool IsGecko() const { return !IsServo(); }
+  bool IsServo() const { return (mBits & NS_STYLE_CONTEXT_IS_GECKO) == 0; }
+#else
+  bool IsGecko() const { return true; }
+  bool IsServo() const { return false; }
+#endif
+  MOZ_DECL_STYLO_CONVERT_METHODS(mozilla::GeckoStyleContext, mozilla::ServoStyleContext);
 
-  // Version of the above that takes a ServoComputedValues instead of a Gecko
-  // nsRuleNode.
-  nsStyleContext(nsStyleContext* aParent,
-                 nsPresContext* aPresContext,
-                 nsIAtom* aPseudoTag,
-                 mozilla::CSSPseudoElementType aPseudoType,
-                 already_AddRefed<ServoComputedValues> aComputedValues);
-
-  void* operator new(size_t sz, nsPresContext* aPresContext);
   void Destroy();
 
   // These two methods are for use by ArenaRefPtr.
   static mozilla::ArenaObjectID ArenaObjectID()
   {
-    return mozilla::eArenaObjectID_nsStyleContext;
+    return mozilla::eArenaObjectID_GeckoStyleContext;
   }
   nsIPresShell* Arena();
 
@@ -154,19 +127,9 @@ public:
     return mRefCnt == 1;
   }
 
-  nsPresContext* PresContext() const {
-#ifdef MOZ_STYLO
-    return mPresContext;
-#else
-    return mSource.AsGeckoRuleNode()->PresContext();
-#endif
-  }
+  inline nsPresContext* PresContext() const;
 
-  nsStyleContext* GetParent() const {
-    MOZ_ASSERT(mSource.IsGeckoRuleNode(),
-               "This should be used only in Gecko-backed style system!");
-    return mParent;
-  }
+  inline mozilla::GeckoStyleContext* GetParent() const;
 
   nsStyleContext* GetParentAllowServo() const {
     return mParent;
@@ -186,19 +149,6 @@ public:
   bool IsPseudoElement() const { return mPseudoTag && !IsAnonBox(); }
 
 
-  // Find, if it already exists *and is easily findable* (i.e., near the
-  // start of the child list), a style context whose:
-  //  * GetPseudo() matches aPseudoTag
-  //  * mSource matches aSource
-  //  * !!GetStyleIfVisited() == !!aSourceIfVisited, and, if they're
-  //    non-null, GetStyleIfVisited()->mSource == aSourceIfVisited
-  //  * RelevantLinkVisited() == aRelevantLinkVisited
-  already_AddRefed<nsStyleContext>
-  FindChildWithRules(const nsIAtom* aPseudoTag,
-                     mozilla::NonOwningStyleContextSource aSource,
-                     mozilla::NonOwningStyleContextSource aSourceIfVisited,
-                     bool aRelevantLinkVisited);
-
   // Does this style context or any of its ancestors have text
   // decoration lines?
   // Differs from nsStyleTextReset::HasTextDecorationLines, which tests
@@ -242,10 +192,7 @@ public:
     { return !!(mBits & NS_STYLE_RELEVANT_LINK_VISITED); }
 
   // Is this a style context for a link?
-  bool IsLinkContext() const {
-    return
-      GetStyleIfVisited() && GetStyleIfVisited()->GetParent() == GetParent();
-  }
+  inline bool IsLinkContext() const;
 
   // Is this style context the GetStyleIfVisited() for some other style
   // context?
@@ -311,9 +258,6 @@ public:
   bool IsShared() const
     { return !!(mBits & NS_STYLE_IS_SHARED); }
 
-  // Tell this style context to cache aStruct as the struct for aSID
-  void SetStyle(nsStyleStructID aSID, void* aStruct);
-
   /**
    * Returns whether this style context has cached style data for a
    * given style struct and it does NOT own that struct.  This can
@@ -324,31 +268,11 @@ public:
     return mBits & nsCachedStyleData::GetBitForSID(aSID);
   }
 
-  nsRuleNode* RuleNode() {
-    MOZ_RELEASE_ASSERT(mSource.IsGeckoRuleNode());
-    return mSource.AsGeckoRuleNode();
-  }
+  inline nsRuleNode* RuleNode();
+  inline ServoComputedValues* ComputedValues();
 
   void AddStyleBit(const uint64_t& aBit) { mBits |= aBit; }
 
-  /*
-   * Get the style data for a style struct.  This is the most important
-   * member function of nsStyleContext.  It fills in a const pointer
-   * to a style data struct that is appropriate for the style context's
-   * frame.  This struct may be shared with other contexts (either in
-   * the rule tree or the style context tree), so it should not be
-   * modified.
-   *
-   * This function will NOT return null (even when out of memory) when
-   * given a valid style struct ID, so the result does not need to be
-   * null-checked.
-   *
-   * The typesafe functions below are preferred to the use of this
-   * function, both because they're easier to read and because they're
-   * faster.
-   */
-  const void* NS_FASTCALL StyleData(nsStyleStructID aSID) MOZ_NONNULL_RETURN;
-
   /**
    * Define typesafe getter functions for each style struct by
    * preprocessing the list of style structs.  These functions are the
@@ -356,10 +280,8 @@ public:
    *   const nsStyleBorder* StyleBorder();
    *   const nsStyleColor* StyleColor();
    */
-  #define STYLE_STRUCT(name_, checkdata_cb_)                   \
-    const nsStyle##name_ * Style##name_() MOZ_NONNULL_RETURN { \
-      return DoGetStyle##name_<true>();                        \
-    }
+  #define STYLE_STRUCT(name_, checkdata_cb_) \
+    inline const nsStyle##name_ * Style##name_() MOZ_NONNULL_RETURN;
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT
 
@@ -370,13 +292,8 @@ public:
    * this style struct. Use with care.
    */
 
-  #define STYLE_STRUCT(name_, checkdata_cb_)                                  \
-    const nsStyle##name_ * ThreadsafeStyle##name_() {                         \
-      if (mozilla::ServoStyleSet::IsInServoTraversal()) {                     \
-        return Servo_GetStyle##name_(mSource.AsServoComputedValues());        \
-      }                                                                       \
-      return Style##name_();                                                  \
-    }
+  #define STYLE_STRUCT(name_, checkdata_cb_) \
+    inline const nsStyle##name_ * ThreadsafeStyle##name_();
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT
 
@@ -388,10 +305,8 @@ public:
    *
    * Perhaps this shouldn't be a public nsStyleContext API.
    */
-  #define STYLE_STRUCT(name_, checkdata_cb_)              \
-    const nsStyle##name_ * PeekStyle##name_() {           \
-      return DoGetStyle##name_<false>();                  \
-    }
+  #define STYLE_STRUCT(name_, checkdata_cb_)  \
+    inline const nsStyle##name_ * PeekStyle##name_();
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT
 
@@ -458,10 +373,7 @@ public:
   /**
    * Start the background image loads for this style context.
    */
-  void StartBackgroundImageLoads() {
-    // Just get our background struct; that should do the trick
-    StyleBackground();
-  }
+  inline void StartBackgroundImageLoads();
 
   /**
    * Moves this style context to a new parent.
@@ -472,104 +384,39 @@ public:
    */
   void MoveTo(nsStyleContext* aNewParent);
 
-  /**
-   * Swaps owned style struct pointers between this and aNewContext, on
-   * the assumption that aNewContext is the new style context for a frame
-   * and this is the old one.  aStructs indicates which structs to consider
-   * swapping; only those which are owned in both this and aNewContext
-   * will be swapped.
-   *
-   * Additionally, if there are identical struct pointers for one of the
-   * structs indicated by aStructs, and it is not an owned struct on this,
-   * then the cached struct slot on this will be set to null.  If the struct
-   * has been swapped on an ancestor, this style context (being the old one)
-   * will be left caching the struct pointer on the new ancestor, despite
-   * inheriting from the old ancestor.  This is not normally a problem, as
-   * this style context will usually be destroyed by being released at the
-   * end of ElementRestyler::Restyle; but for style contexts held on to outside
-   * of the frame, we need to clear out the cached pointer so that if we need
-   * it again we'll re-fetch it from the new ancestor.
-   */
-  void SwapStyleData(nsStyleContext* aNewContext, uint32_t aStructs);
-
-  /**
-   * On each descendant of this style context, clears out any cached inherited
-   * structs indicated in aStructs.
-   */
-  void ClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
-
-  /**
-   * Sets the NS_STYLE_INELIGIBLE_FOR_SHARING bit on this style context
-   * and its descendants.  If it finds a descendant that has the bit
-   * already set, assumes that it can skip that subtree.
-   */
-  void SetIneligibleForSharing();
-
 #ifdef DEBUG
   void List(FILE* out, int32_t aIndent, bool aListDescendants = true);
   static const char* StructName(nsStyleStructID aSID);
   static bool LookupStruct(const nsACString& aName, nsStyleStructID& aResult);
 #endif
 
-#ifdef RESTYLE_LOGGING
-  nsCString GetCachedStyleDataAsString(uint32_t aStructs);
-  void LogStyleContextTree(int32_t aLoggingDepth, uint32_t aStructs);
-  int32_t& LoggingDepth();
-#endif
-
-  /**
-   * Return style data that is currently cached on the style context.
-   * Only returns the structs we cache ourselves; never consults the
-   * rule tree.
-   *
-   * For "internal" use only in nsStyleContext and nsRuleNode.
-   */
-  const void* GetCachedStyleData(nsStyleStructID aSID)
-  {
-    const void* cachedData;
-    if (nsCachedStyleData::IsReset(aSID)) {
-      if (mCachedResetData) {
-        cachedData = mCachedResetData->mStyleStructs[aSID];
-      } else {
-        cachedData = nullptr;
-      }
-    } else {
-      cachedData = mCachedInheritedData.mStyleStructs[aSID];
-    }
-    return cachedData;
-  }
-
-  mozilla::NonOwningStyleContextSource StyleSource() const { return mSource.AsRaw(); }
-
-private:
-  // Private destructor, to discourage deletion outside of Release():
-  ~nsStyleContext();
-
+protected:
+  // protected destructor to discourage deletion outside of Release()
+  ~nsStyleContext() {}
+  // Where the actual destructor lives
+  // We use this instead of a real destructor because we need
+  // this to be called *before* the subclass fields are destroyed
+  // by the subclass destructor
+  void Destructor();
   // Delegated Helper constructor.
   nsStyleContext(nsStyleContext* aParent,
-                 mozilla::OwningStyleContextSource&& aSource,
                  nsIAtom* aPseudoTag,
                  mozilla::CSSPseudoElementType aPseudoType);
 
   // Helper post-contruct hook.
   void FinishConstruction();
 
+  // Only does stuff in Gecko mode
   void AddChild(nsStyleContext* aChild);
   void RemoveChild(nsStyleContext* aChild);
 
-  void* GetUniqueStyleData(const nsStyleStructID& aSID);
-  void* CreateEmptyStyleData(const nsStyleStructID& aSID);
-
   void SetStyleBits();
 
-  // Only called for Gecko-backed nsStyleContexts.
-  void ApplyStyleFixups(bool aSkipParentDisplayBasedStyleFixup);
-
   const void* StyleStructFromServoComputedValues(nsStyleStructID aSID) {
     switch (aSID) {
 #define STYLE_STRUCT(name_, checkdata_cb_)                                    \
       case eStyleStruct_##name_:                                              \
-        return Servo_GetStyle##name_(mSource.AsServoComputedValues());
+        return Servo_GetStyle##name_(ComputedValues());
 #include "nsStyleStructList.h"
 #undef STYLE_STRUCT
       default:
@@ -610,139 +457,17 @@ private:
   // Helper functions for GetStyle* and PeekStyle*
   #define STYLE_STRUCT_INHERITED(name_, checkdata_cb_)                  \
     template<bool aComputeData>                                         \
-    const nsStyle##name_ * DoGetStyle##name_() {                        \
-      if (mSource.IsGeckoRuleNode()) {                                  \
-        const nsStyle##name_ * cachedData =                             \
-          static_cast<nsStyle##name_*>(                                 \
-            mCachedInheritedData.mStyleStructs[eStyleStruct_##name_]);  \
-        if (cachedData) /* Have it cached already, yay */               \
-          return cachedData;                                            \
-        if (!aComputeData) {                                            \
-          /* We always cache inherited structs on the context when we */\
-          /* compute them. */                                           \
-          return nullptr;                                               \
-        }                                                               \
-        /* Have the rulenode deal */                                    \
-        AUTO_CHECK_DEPENDENCY(eStyleStruct_##name_);                    \
-        const nsStyle##name_ * newData =                                \
-          mSource.AsGeckoRuleNode()->                                   \
-            GetStyle##name_<aComputeData>(this, mBits);                 \
-        /* always cache inherited data on the style context; the rule */\
-        /* node set the bit in mBits for us if needed. */               \
-        mCachedInheritedData.mStyleStructs[eStyleStruct_##name_] =      \
-          const_cast<nsStyle##name_ *>(newData);                        \
-        return newData;                                                 \
-      }                                                                 \
-      /**                                                               \
-       * Also (conservatively) set the owning bit in the parent style   \
-       * context if we're a text node.                                  \
-       *                                                                \
-       * This causes the parent element's style context to cache any    \
-       * inherited structs we request for a text node, which means we   \
-       * don't have to compute change hints for the text node, as       \
-       * handling the change on the parent element is sufficient.       \
-       *                                                                \
-       * Note, however, that we still need to request the style struct  \
-       * of the text node itself, since we may run some fixups on it,   \
-       * like for text-combine.                                         \
-       *                                                                \
-       * This model is sound because for the fixed-up values to change, \
-       * other properties on the parent need to change too, and we'll   \
-       * handle those change hints correctly.                           \
-       *                                                                \
-       * TODO(emilio): Perhaps we should remove those fixups and handle \
-       * those in layout instead. Those fixups are kind of expensive    \
-       * for style sharing, and computed style of text nodes is not     \
-       * observable. If we do that, we could assert here that the       \
-       * inherited structs of both are the same.                        \
-       */                                                               \
-      if (mPseudoTag == nsCSSAnonBoxes::mozText && aComputeData) {      \
-        MOZ_ASSERT(mParent);                                            \
-        mParent->AddStyleBit(NS_STYLE_INHERIT_BIT(name_));              \
-      }                                                                 \
-                                                                        \
-      const bool needToCompute = !(mBits & NS_STYLE_INHERIT_BIT(name_));\
-      if (!aComputeData && needToCompute) {                             \
-        return nullptr;                                                 \
-      }                                                                 \
-                                                                        \
-      const nsStyle##name_* data =                                      \
-        Servo_GetStyle##name_(mSource.AsServoComputedValues());         \
-      /* perform any remaining main thread work on the struct */        \
-      if (needToCompute) {                                              \
-        MOZ_ASSERT(NS_IsMainThread());                                  \
-        MOZ_ASSERT(!mozilla::ServoStyleSet::IsInServoTraversal());      \
-        const_cast<nsStyle##name_*>(data)->FinishStyle(PresContext());  \
-        /* the Servo-backed StyleContextSource owns the struct */       \
-        AddStyleBit(NS_STYLE_INHERIT_BIT(name_));                       \
-      }                                                                 \
-      return data;                                                      \
-    }
-
+    const nsStyle##name_ * DoGetStyle##name_();
   #define STYLE_STRUCT_RESET(name_, checkdata_cb_)                      \
     template<bool aComputeData>                                         \
-    const nsStyle##name_ * DoGetStyle##name_() {                        \
-      if (mSource.IsGeckoRuleNode()) {                                  \
-        if (mCachedResetData) {                                         \
-          const nsStyle##name_ * cachedData =                           \
-            static_cast<nsStyle##name_*>(                               \
-              mCachedResetData->mStyleStructs[eStyleStruct_##name_]);   \
-          if (cachedData) /* Have it cached already, yay */             \
-            return cachedData;                                          \
-        }                                                               \
-        /* Have the rulenode deal */                                    \
-        AUTO_CHECK_DEPENDENCY(eStyleStruct_##name_);                    \
-        return mSource.AsGeckoRuleNode()->                              \
-          GetStyle##name_<aComputeData>(this);                          \
-      }                                                                 \
-      const bool needToCompute = !(mBits & NS_STYLE_INHERIT_BIT(name_));\
-      if (!aComputeData && needToCompute) {                             \
-        return nullptr;                                                 \
-      }                                                                 \
-      const nsStyle##name_* data =                                      \
-        Servo_GetStyle##name_(mSource.AsServoComputedValues());         \
-      /* perform any remaining main thread work on the struct */        \
-      if (needToCompute) {                                              \
-        const_cast<nsStyle##name_*>(data)->FinishStyle(PresContext());  \
-        /* the Servo-backed StyleContextSource owns the struct */       \
-        AddStyleBit(NS_STYLE_INHERIT_BIT(name_));                       \
-      }                                                                 \
-      return data;                                                      \
-    }
+    const nsStyle##name_ * DoGetStyle##name_();
+
   #include "nsStyleStructList.h"
   #undef STYLE_STRUCT_RESET
   #undef STYLE_STRUCT_INHERITED
 
-  // Helper for ClearCachedInheritedStyleDataOnDescendants.
-  void DoClearCachedInheritedStyleDataOnDescendants(uint32_t aStructs);
-
-#ifdef DEBUG
-  void AssertStructsNotUsedElsewhere(nsStyleContext* aDestroyingContext,
-                                     int32_t aLevels) const;
-#endif
-
-#ifdef RESTYLE_LOGGING
-  void LogStyleContextTree(bool aFirst, uint32_t aStructs);
-
-  // This only gets called under call trees where we've already checked
-  // that PresContext()->RestyleManager()->ShouldLogRestyle() returned true.
-  // It exists here just to satisfy LOG_RESTYLE's expectations.
-  bool ShouldLogRestyle() { return true; }
-#endif
-
   RefPtr<nsStyleContext> mParent;
 
-  // Children are kept in two circularly-linked lists.  The list anchor
-  // is not part of the list (null for empty), and we point to the first
-  // child.
-  // mEmptyChild for children whose rule node is the root rule node, and
-  // mChild for other children.  The order of children is not
-  // meaningful.
-  nsStyleContext* mChild;
-  nsStyleContext* mEmptyChild;
-  nsStyleContext* mPrevSibling;
-  nsStyleContext* mNextSibling;
-
   // Style to be used instead for the R, G, and B components of color,
   // background-color, and border-*-color if the nearest ancestor link
   // element is visited (see RelevantLinkVisited()).
@@ -752,29 +477,6 @@ private:
   // the relevant atom.
   nsCOMPtr<nsIAtom> mPseudoTag;
 
-  // The source for our style data, either a Gecko nsRuleNode or a Servo
-  // ComputedValues struct. This never changes after construction, except
-  // when it's released and nulled out during teardown.
-  const mozilla::OwningStyleContextSource mSource;
-
-#ifdef MOZ_STYLO
-  // In Gecko, we can get this off the rule node. We make this conditional
-  // on stylo builds to avoid the memory bloat on release.
-  nsPresContext* mPresContext;
-#endif
-
-  // mCachedInheritedData and mCachedResetData point to both structs that
-  // are owned by this style context and structs that are owned by one of
-  // this style context's ancestors (which are indirectly owned since this
-  // style context owns a reference to its parent).  If the bit in |mBits|
-  // is set for a struct, that means that the pointer for that struct is
-  // owned by an ancestor or by the rule node rather than by this style context.
-  // Since style contexts typically have some inherited data but only sometimes
-  // have reset data, we always allocate the mCachedInheritedData, but only
-  // sometimes allocate the mCachedResetData.
-  nsResetStyleData*       mCachedResetData; // Cached reset style data.
-  nsInheritedStyleData    mCachedInheritedData; // Cached inherited style data
-
   // mBits stores a number of things:
   //  - It records (using the style struct bits) which structs are
   //    inherited from the parent context or owned by the rule node (i.e.,

layout/style/nsStyleContextInlines.h

@@ -0,0 +1,199 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+
+/*
+ * Inlined methods for nsStyleContext. Will just redirect to
+ * GeckoStyleContext methods when compiled without stylo, but will do
+ * virtual dispatch (by checking which kind of container it is)
+ * in stylo mode.
+ */
+
+#ifndef nsStyleContextInlines_h
+#define nsStyleContextInlines_h
+
+#include "nsStyleContext.h"
+#include "mozilla/ServoStyleContext.h"
+#include "mozilla/GeckoStyleContext.h"
+#include "mozilla/ServoUtils.h"
+
+MOZ_DEFINE_STYLO_METHODS(nsStyleContext,
+                         mozilla::GeckoStyleContext,
+                         mozilla::ServoStyleContext);
+
+nsRuleNode*
+nsStyleContext::RuleNode()
+{
+    MOZ_RELEASE_ASSERT(IsGecko());
+    return AsGecko()->RuleNode();
+}
+
+ServoComputedValues*
+nsStyleContext::ComputedValues()
+{
+    MOZ_RELEASE_ASSERT(IsServo());
+    return AsServo()->ComputedValues();
+}
+
+#define STYLE_STRUCT(name_, checkdata_cb_)                      \
+const nsStyle##name_ *                                          \
+nsStyleContext::Style##name_() {                                \
+  return DoGetStyle##name_<true>();                             \
+}                                                               \
+const nsStyle##name_ *                                          \
+nsStyleContext::ThreadsafeStyle##name_() {                      \
+  if (mozilla::ServoStyleSet::IsInServoTraversal()) {           \
+    return Servo_GetStyle##name_(AsServo()->ComputedValues());  \
+  }                                                             \
+  return Style##name_();                                        \
+}                                                               \
+const nsStyle##name_ * nsStyleContext::PeekStyle##name_() {     \
+  return DoGetStyle##name_<false>();                            \
+}
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT
+
+// Helper functions for GetStyle* and PeekStyle*
+#define STYLE_STRUCT_INHERITED(name_, checkdata_cb_)                \
+template<bool aComputeData>                                         \
+const nsStyle##name_ * nsStyleContext::DoGetStyle##name_() {        \
+  if (auto gecko = GetAsGecko()) {                                  \
+    const nsStyle##name_ * cachedData =                             \
+      static_cast<nsStyle##name_*>(                                 \
+        gecko->mCachedInheritedData                                 \
+        .mStyleStructs[eStyleStruct_##name_]);                      \
+    if (cachedData) /* Have it cached already, yay */               \
+      return cachedData;                                            \
+    if (!aComputeData) {                                            \
+      /* We always cache inherited structs on the context when we */\
+      /* compute them. */                                           \
+      return nullptr;                                               \
+    }                                                               \
+    /* Have the rulenode deal */                                    \
+    AUTO_CHECK_DEPENDENCY(eStyleStruct_##name_);                    \
+    const nsStyle##name_ * newData =                                \
+      gecko->RuleNode()->                                           \
+        GetStyle##name_<aComputeData>(this->AsGecko(), mBits);      \
+    /* always cache inherited data on the style context; the rule */\
+    /* node set the bit in mBits for us if needed. */               \
+    gecko->mCachedInheritedData                                     \
+      .mStyleStructs[eStyleStruct_##name_] =                        \
+      const_cast<nsStyle##name_ *>(newData);                        \
+    return newData;                                                 \
+  }                                                                 \
+  auto servo = AsServo();                                           \
+  /**                                                               \
+   * Also (conservatively) set the owning bit in the parent style   \
+   * context if we're a text node.                                  \
+   *                                                                \
+   * This causes the parent element's style context to cache any    \
+   * inherited structs we request for a text node, which means we   \
+   * don't have to compute change hints for the text node, as       \
+   * handling the change on the parent element is sufficient.       \
+   *                                                                \
+   * Note, however, that we still need to request the style struct  \
+   * of the text node itself, since we may run some fixups on it,   \
+   * like for text-combine.                                         \
+   *                                                                \
+   * This model is sound because for the fixed-up values to change, \
+   * other properties on the parent need to change too, and we'll   \
+   * handle those change hints correctly.                           \
+   *                                                                \
+   * TODO(emilio): Perhaps we should remove those fixups and handle \
+   * those in layout instead. Those fixups are kind of expensive    \
+   * for style sharing, and computed style of text nodes is not     \
+   * observable. If we do that, we could assert here that the       \
+   * inherited structs of both are the same.                        \
+   */                                                               \
+  if (mPseudoTag == nsCSSAnonBoxes::mozText && aComputeData) {      \
+    MOZ_ASSERT(mParent);                                            \
+    mParent->AddStyleBit(NS_STYLE_INHERIT_BIT(name_));              \
+  }                                                                 \
+                                                                    \
+  const bool needToCompute = !(mBits & NS_STYLE_INHERIT_BIT(name_));\
+  if (!aComputeData && needToCompute) {                             \
+    return nullptr;                                                 \
+  }                                                                 \
+                                                                    \
+  const nsStyle##name_* data =                                      \
+    Servo_GetStyle##name_(servo->ComputedValues());   \
+  /* perform any remaining main thread work on the struct */        \
+  if (needToCompute) {                                              \
+    MOZ_ASSERT(NS_IsMainThread());                                  \
+    MOZ_ASSERT(!mozilla::ServoStyleSet::IsInServoTraversal());      \
+    const_cast<nsStyle##name_*>(data)->FinishStyle(PresContext());  \
+    /* the ServoStyleContext owns the struct */                     \
+    AddStyleBit(NS_STYLE_INHERIT_BIT(name_));                       \
+  }                                                                 \
+  return data;                                                      \
+}
+
+#define STYLE_STRUCT_RESET(name_, checkdata_cb_)                              \
+template<bool aComputeData>                                                   \
+const nsStyle##name_ * nsStyleContext::DoGetStyle##name_() {                  \
+  if (auto gecko = GetAsGecko()) {                                            \
+    if (gecko->mCachedResetData) {                                            \
+      const nsStyle##name_ * cachedData =                                     \
+        static_cast<nsStyle##name_*>(                                         \
+          gecko->mCachedResetData->mStyleStructs[eStyleStruct_##name_]);      \
+      if (cachedData) /* Have it cached already, yay */                       \
+        return cachedData;                                                    \
+    }                                                                         \
+    /* Have the rulenode deal */                                              \
+    AUTO_CHECK_DEPENDENCY(eStyleStruct_##name_);                              \
+    return gecko->RuleNode()->GetStyle##name_<aComputeData>(this->AsGecko()); \
+  }                                                                           \
+  auto servo = AsServo();                                                     \
+  const bool needToCompute = !(mBits & NS_STYLE_INHERIT_BIT(name_));          \
+  if (!aComputeData && needToCompute) {                                       \
+    return nullptr;                                                           \
+  }                                                                           \
+  const nsStyle##name_* data =                                                \
+    Servo_GetStyle##name_(servo->ComputedValues());                           \
+  /* perform any remaining main thread work on the struct */                  \
+  if (needToCompute) {                                                        \
+    const_cast<nsStyle##name_*>(data)->FinishStyle(PresContext());            \
+    /* the ServoStyleContext owns the struct */                               \
+    AddStyleBit(NS_STYLE_INHERIT_BIT(name_));                                 \
+  }                                                                           \
+  return data;                                                                \
+}
+#include "nsStyleStructList.h"
+#undef STYLE_STRUCT_RESET
+#undef STYLE_STRUCT_INHERITED
+
+
+nsPresContext*
+nsStyleContext::PresContext() const
+{
+    MOZ_STYLO_FORWARD(PresContext, ())
+}
+
+mozilla::GeckoStyleContext*
+nsStyleContext::GetParent() const
+{
+  MOZ_ASSERT(IsGecko(),
+             "This should be used only in Gecko-backed style system!");
+  if (mParent) {
+    return mParent->AsGecko();
+  } else {
+    return nullptr;
+  }
+}
+
+bool
+nsStyleContext::IsLinkContext() const
+{
+  return GetStyleIfVisited() && GetStyleIfVisited()->GetParent() == GetParent();
+}
+
+void
+nsStyleContext::StartBackgroundImageLoads()
+{
+  // Just get our background struct; that should do the trick
+  StyleBackground();
+}
+
+#endif // nsStyleContextInlines_h

layout/style/nsStyleSet.cpp

@@ -43,6 +43,7 @@
 #include "mozilla/RestyleManager.h"
 #include "mozilla/RestyleManagerInlines.h"
 #include "nsQueryObject.h"
+#include "nsStyleContextInlines.h"
 
 #include <inttypes.h>
 
@@ -308,7 +309,7 @@ nsStyleSet::BeginReconstruct()
 
   // Clear any ArenaRefPtr-managed style contexts, as we don't want them
   // held on to after the rule tree has been reconstructed.
-  PresContext()->PresShell()->ClearArenaRefPtrs(eArenaObjectID_nsStyleContext);
+  PresContext()->PresShell()->ClearArenaRefPtrs(eArenaObjectID_GeckoStyleContext);
 
   // Clear our cached style contexts for non-inheriting anonymous boxes.
   ClearNonInheritingStyleContexts();
@@ -926,7 +927,7 @@ nsStyleSet::GetContext(nsStyleContext* aParentContext,
 
   RefPtr<nsStyleContext> result;
   if (aParentContext)
-    result = aParentContext->FindChildWithRules(aPseudoTag, aRuleNode,
+    result = aParentContext->AsGecko()->FindChildWithRules(aPseudoTag, aRuleNode,
                                                 aVisitedRuleNode,
                                                 relevantLinkVisited);
 

layout/style/nsStyleStruct.h

@@ -93,8 +93,10 @@ class ImageTracker;
 #define NS_STYLE_HAS_CHILD_THAT_USES_RESET_STYLE 0x400000000
 // See nsStyleContext::IsTextCombined
 #define NS_STYLE_IS_TEXT_COMBINED          0x800000000
+// Whether a style context is a Gecko or Servo context
+#define NS_STYLE_CONTEXT_IS_GECKO          0x1000000000
 // See nsStyleContext::GetPseudoEnum
-#define NS_STYLE_CONTEXT_TYPE_SHIFT        36
+#define NS_STYLE_CONTEXT_TYPE_SHIFT        37
 
 // Additional bits for nsRuleNode's mDependentBits:
 #define NS_RULE_NODE_IS_ANIMATION_RULE      0x01000000

layout/style/nsStyleTransformMatrix.cpp

@@ -514,7 +514,7 @@ ProcessMatrixOperator(Matrix4x4& aMatrix,
   Matrix4x4 matrix2 = readTransform(aData->Item(2));
   double progress = aData->Item(3).GetPercentValue();
 
-  if (aContext && aContext->StyleSource().IsServoComputedValues()) {
+  if (aContext && aContext->IsServo()) {
     aMatrix =
       OperateTransformMatrixByServo<Operator>(matrix1, matrix2, progress)
         * aMatrix;

layout/tables/nsTableColGroupFrame.cpp

@@ -13,6 +13,7 @@
 #include "nsCOMPtr.h"
 #include "nsCSSRendering.h"
 #include "nsIPresShell.h"
+#include "mozilla/GeckoStyleContext.h"
 
 using namespace mozilla;
 
@@ -296,9 +297,9 @@ nsTableColGroupFrame::RemoveFrame(ChildListID     aListID,
 #ifdef DEBUG
         nsIFrame* providerFrame;
         nsStyleContext* psc = colFrame->GetParentStyleContext(&providerFrame);
-        if (psc->StyleSource().IsGeckoRuleNodeOrNull()) {
+        if (psc->IsGecko()) {
           // This check code is useful only in Gecko-backed style system.
-          if (colFrame->StyleContext()->GetParent() == psc) {
+          if (static_cast<nsStyleContext*>(colFrame->StyleContext()->GetParent()) == psc) {
             NS_ASSERTION(col->StyleContext() == colFrame->StyleContext() &&
                          col->GetContent() == colFrame->GetContent(),
                          "How did that happen??");

layout/tools/reftest/runreftest.py

@@ -57,6 +57,8 @@ except ImportError:
 
 def categoriesToRegex(categoryList):
     return "\\(" + ', '.join(["(?P<%s>\\d+) %s" % c for c in categoryList]) + "\\)"
+
+
 summaryLines = [('Successful', [('pass', 'pass'), ('loadOnly', 'load only')]),
                 ('Unexpected', [('fail', 'unexpected fail'),
                                 ('pass', 'unexpected pass'),

layout/xul/nsMenuPopupFrame.cpp

@@ -118,6 +118,7 @@ nsMenuPopupFrame::nsMenuPopupFrame(nsStyleContext* aContext)
   , mInContentShell(true)
   , mIsMenuLocked(false)
   , mMouseTransparent(false)
+  , mIsOffset(false)
   , mHFlip(false)
   , mVFlip(false)
   , mAnchorType(MenuPopupAnchorType_Node)
@@ -601,7 +602,7 @@ nsMenuPopupFrame::LayoutPopup(nsBoxLayoutState& aState, nsIFrame* aParentMenu,
 bool
 nsMenuPopupFrame::ReflowFinished()
 {
-  SetPopupPosition(mReflowCallbackData.mAnchor, false, mReflowCallbackData.mSizedToPopup, false);
+  SetPopupPosition(mReflowCallbackData.mAnchor, false, mReflowCallbackData.mSizedToPopup, true);
 
   mReflowCallbackData.Clear();
 
@@ -1558,10 +1559,14 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aS
 #endif // #ifdef XP_MACOSX
   }
 
-  // If a panel is being moved or has flip="none", don't constrain or flip it. But always do this for
+  nscoord oldAlignmentOffset = mAlignmentOffset;
+
+  // If a panel is being moved or has flip="none", don't constrain or flip it, in order to avoid
+  // visual noise when moving windows between screens. However, if a panel is already constrained
+  // or flipped (mIsOffset), then we want to continue to calculate this. Also, always do this for
   // content shells, so that the popup doesn't extend outside the containing frame.
   if (mInContentShell || (mFlip != FlipType_None &&
-                          (!aIsMove || mPopupType != ePopupTypePanel))) {
+                          (!aIsMove || mIsOffset || mPopupType != ePopupTypePanel))) {
     int32_t appPerDev = presContext->AppUnitsPerDevPixel();
     LayoutDeviceIntRect anchorRectDevPix =
       LayoutDeviceIntRect::FromAppUnitsToNearest(anchorRect, appPerDev);
@@ -1602,6 +1607,7 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aS
     bool endAligned = IsDirectionRTL() ?
       mPopupAlignment == POPUPALIGNMENT_TOPLEFT || mPopupAlignment == POPUPALIGNMENT_BOTTOMLEFT :
       mPopupAlignment == POPUPALIGNMENT_TOPRIGHT || mPopupAlignment == POPUPALIGNMENT_BOTTOMRIGHT;
+    nscoord preOffsetScreenPoint = screenPoint.x;
     if (slideHorizontal) {
       mRect.width = SlideOrResize(screenPoint.x, mRect.width, screenRect.x,
                                   screenRect.XMost(), &mAlignmentOffset);
@@ -1611,9 +1617,11 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aS
                                  margin.left, margin.right, offsetForContextMenu.x, hFlip,
                                  endAligned, &mHFlip);
     }
+    mIsOffset = preOffsetScreenPoint != screenPoint.x;
 
     endAligned = mPopupAlignment == POPUPALIGNMENT_BOTTOMLEFT ||
                  mPopupAlignment == POPUPALIGNMENT_BOTTOMRIGHT;
+    preOffsetScreenPoint = screenPoint.y;
     if (slideVertical) {
       mRect.height = SlideOrResize(screenPoint.y, mRect.height, screenRect.y,
                                   screenRect.YMost(), &mAlignmentOffset);
@@ -1623,6 +1631,7 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aS
                                   margin.top, margin.bottom, offsetForContextMenu.y, vFlip,
                                   endAligned, &mVFlip);
     }
+    mIsOffset = mIsOffset || (preOffsetScreenPoint != screenPoint.y);
 
     NS_ASSERTION(screenPoint.x >= screenRect.x && screenPoint.y >= screenRect.y &&
                  screenPoint.x + mRect.width <= screenRect.XMost() &&
@@ -1669,7 +1678,8 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame, bool aIsMove, bool aS
   // or size changed, dispatch a popuppositioned event if the popup wants it.
   nsIntRect newRect(screenPoint.x, screenPoint.y, mRect.width, mRect.height);
   if (mPopupState == ePopupPositioning ||
-      (mPopupState == ePopupShown && !newRect.IsEqualEdges(mUsedScreenRect))) {
+      (mPopupState == ePopupShown && !newRect.IsEqualEdges(mUsedScreenRect)) ||
+      (mPopupState == ePopupShown && oldAlignmentOffset != mAlignmentOffset)) {
     mUsedScreenRect = newRect;
     if (aNotify) {
       nsXULPopupPositionedEvent::DispatchIfNeeded(mContent, false, false);

layout/xul/nsMenuPopupFrame.h

@@ -636,6 +636,11 @@ protected:
   bool mIsMenuLocked; // Should events inside this menu be ignored?
   bool mMouseTransparent; // True if this is a popup is transparent to mouse events
 
+  // True if this popup has been offset due to moving off / near the edge of the screen.
+  // (This is useful for ensuring that a move, which can't offset the popup, doesn't undo
+  // a previously set offset.)
+  bool mIsOffset;
+
   // the flip modes that were used when the popup was opened
   bool mHFlip;
   bool mVFlip;

layout/xul/nsSplitterFrame.cpp

@@ -29,6 +29,7 @@
 #include "nsIServiceManager.h"
 #include "nsContainerFrame.h"
 #include "nsContentCID.h"
+#include "mozilla/GeckoStyleContext.h"
 #include "mozilla/StyleSetHandle.h"
 #include "mozilla/StyleSetHandleInlines.h"
 #include "nsLayoutUtils.h"
@@ -284,7 +285,7 @@ nsSplitterFrame::Init(nsIContent*       aContent,
                                            nsGkAtoms::orient)) {
         aContent->SetAttr(kNameSpaceID_None, nsGkAtoms::orient,
                           NS_LITERAL_STRING("vertical"), false);
-        nsStyleContext* parentStyleContext = StyleContext()->GetParent();
+        GeckoStyleContext* parentStyleContext = StyleContext()->GetParent();
         RefPtr<nsStyleContext> newContext = PresContext()->StyleSet()->
           ResolveStyleFor(aContent->AsElement(), parentStyleContext,
                           LazyComputeBehavior::Allow);