Bug 1366157 - stylo: Implement getDefaultComputedStyle. r=emilio

MozReview-Commit-ID: GKr06ylK4tA

--HG--
extra : rebase_source : 04907d98d62a0b06f7d3753aaedf999b63483a77

layout/style/ServoBindingList.h

@@ -453,6 +453,7 @@ SERVO_BINDING_FUNC(Servo_HasAuthorSpecifiedRules, bool,
 SERVO_BINDING_FUNC(Servo_ResolveStyleLazily, ServoComputedValuesStrong,
                    RawGeckoElementBorrowed element,
                    mozilla::CSSPseudoElementType pseudo_type,
+                   mozilla::StyleRuleInclusion rule_inclusion,
                    const mozilla::ServoElementSnapshotTable* snapshots,
                    RawServoStyleSetBorrowed set)
 

layout/style/ServoBindings.toml

@@ -250,6 +250,7 @@ whitelist-types = [
     "mozilla::binding_danger::AssertAndSuppressCleanupPolicy",
     "mozilla::ParsingMode",
     "mozilla::InheritTarget",
+    "mozilla::StyleRuleInclusion",
 ]
 opaque-types = [
     "std::pair__PCCP",
@@ -426,6 +427,7 @@ structs-types = [
     "ParsingMode",
     "InheritTarget",
     "URLMatchingFunction",
+    "StyleRuleInclusion",
 ]
 array-types = [
     { cpp-type = "uintptr_t", rust-type = "usize" },

layout/style/ServoStyleSet.cpp

@@ -476,10 +476,11 @@ ServoStyleSet::ResolvePseudoElementStyle(Element* aOriginatingElement,
 already_AddRefed<nsStyleContext>
 ServoStyleSet::ResolveTransientStyle(Element* aElement,
                                      nsIAtom* aPseudoTag,
-                                     CSSPseudoElementType aPseudoType)
+                                     CSSPseudoElementType aPseudoType,
+                                     StyleRuleInclusion aRuleInclusion)
 {
   RefPtr<ServoComputedValues> computedValues =
-    ResolveTransientServoStyle(aElement, aPseudoType);
+    ResolveTransientServoStyle(aElement, aPseudoType, aRuleInclusion);
 
   return GetContext(computedValues.forget(),
                     nullptr,
@@ -488,11 +489,13 @@ ServoStyleSet::ResolveTransientStyle(Element* aElement,
 }
 
 already_AddRefed<ServoComputedValues>
-ServoStyleSet::ResolveTransientServoStyle(Element* aElement,
-                                          CSSPseudoElementType aPseudoType)
+ServoStyleSet::ResolveTransientServoStyle(
+    Element* aElement,
+    CSSPseudoElementType aPseudoType,
+    StyleRuleInclusion aRuleInclusion)
 {
   PreTraverseSync();
-  return ResolveStyleLazily(aElement, aPseudoType);
+  return ResolveStyleLazily(aElement, aPseudoType, aRuleInclusion);
 }
 
 already_AddRefed<nsStyleContext>
@@ -1049,7 +1052,8 @@ ServoStyleSet::ClearNonInheritingStyleContexts()
 
 already_AddRefed<ServoComputedValues>
 ServoStyleSet::ResolveStyleLazily(Element* aElement,
-                                  CSSPseudoElementType aPseudoType)
+                                  CSSPseudoElementType aPseudoType,
+                                  StyleRuleInclusion aRuleInclusion)
 {
   mPresContext->EffectCompositor()->PreTraverse(aElement, aPseudoType);
   MOZ_ASSERT(!StylistNeedsUpdate());
@@ -1084,6 +1088,7 @@ ServoStyleSet::ResolveStyleLazily(Element* aElement,
   RefPtr<ServoComputedValues> computedValues =
     Servo_ResolveStyleLazily(elementForStyleResolution,
                              pseudoTypeForStyleResolution,
+                             aRuleInclusion,
                              &Snapshots(),
                              mRawSet.get()).Consume();
 
@@ -1091,6 +1096,7 @@ ServoStyleSet::ResolveStyleLazily(Element* aElement,
     computedValues =
       Servo_ResolveStyleLazily(elementForStyleResolution,
                                pseudoTypeForStyleResolution,
+                               aRuleInclusion,
                                &Snapshots(),
                                mRawSet.get()).Consume();
   }

layout/style/ServoStyleSet.h

@@ -172,13 +172,17 @@ public:
   already_AddRefed<nsStyleContext>
   ResolveTransientStyle(dom::Element* aElement,
                         nsIAtom* aPseudoTag,
-                        CSSPseudoElementType aPseudoType);
+                        CSSPseudoElementType aPseudoType,
+                        StyleRuleInclusion aRules =
+                          StyleRuleInclusion::All);
 
   // Similar to ResolveTransientStyle() but returns ServoComputedValues.
   // Unlike ResolveServoStyle() this function calls PreTraverseSync().
   already_AddRefed<ServoComputedValues>
   ResolveTransientServoStyle(dom::Element* aElement,
-                             CSSPseudoElementType aPseudoTag);
+                             CSSPseudoElementType aPseudoTag,
+                             StyleRuleInclusion aRules =
+                               StyleRuleInclusion::All);
 
   // Get a style context for an anonymous box.  aPseudoTag is the pseudo-tag to
   // use and must be non-null.  It must be an anon box, and must be one that
@@ -491,7 +495,10 @@ private:
   void UpdateStylist();
 
   already_AddRefed<ServoComputedValues>
-    ResolveStyleLazily(dom::Element* aElement, CSSPseudoElementType aPseudoType);
+    ResolveStyleLazily(dom::Element* aElement,
+                       CSSPseudoElementType aPseudoType,
+                       StyleRuleInclusion aRules =
+                         StyleRuleInclusion::All);
 
   void RunPostTraversalTasks();
 

layout/style/ServoTypes.h

@@ -73,6 +73,15 @@ enum class TraversalRestyleBehavior {
   ForCSSRuleChanges,
 };
 
+// Indicates which rules should be included when performing selecting matching
+// on an element.  DefaultOnly is used to exclude all rules except for those
+// that come from UA style sheets, and is used to implemented
+// getDefaultComputedStyle.
+enum class StyleRuleInclusion {
+  All,
+  DefaultOnly,
+};
+
 // Represents which tasks are performed in a SequentialTask of UpdateAnimations.
 enum class UpdateAnimationsTasks : uint8_t {
   CSSAnimations    = 1 << 0,

layout/style/nsComputedDOMStyle.cpp

@@ -662,11 +662,10 @@ nsComputedDOMStyle::DoGetStyleContextNoFlush(Element* aElement,
   // For Servo, compute the result directly without recursively building up
   // a throwaway style context chain.
   if (ServoStyleSet* servoSet = styleSet->GetAsServo()) {
-    if (aStyleType == eDefaultOnly) {
-      NS_WARNING("stylo: ServoStyleSets cannot supply UA-only styles yet");
-      return nullptr;
-    }
-    return servoSet->ResolveTransientStyle(aElement, aPseudo, type);
+    StyleRuleInclusion rules = aStyleType == eDefaultOnly
+                               ? StyleRuleInclusion::DefaultOnly
+                               : StyleRuleInclusion::All;
+    return servoSet->ResolveTransientStyle(aElement, aPseudo, type, rules);
   }
 
   RefPtr<nsStyleContext> parentContext;