Bug 1057129 patch 1 - Make AddStyleUpdatesTo handle pseudo-elements. r=birtles

This (like patch 2) posts restyles directly to the pseudo-element
content nodes, which is a new thing.

This isn't needed right now since AddStyleUpdatesTo is currently only
used when updating main-thread-suppressed animations running on the
compositor.  However, it will be needed once we depend on
AddStyleUpdatesTo for bug 960465.  And it will have an effect now since
AddStyleUpdatesTo actually adds all animations rather than only the ones
that are suppressed from running on the main thread.

layout/style/AnimationCommon.cpp

@@ -176,17 +176,12 @@ CommonAnimationManager::AddStyleUpdatesTo(RestyleTracker& aTracker)
       static_cast<AnimationPlayerCollection*>(next);
     next = PR_NEXT_LINK(next);
 
-    if (!collection->IsForElement()) {
-      // We don't support compositor-driven animation of :before/:after
-      // transitions or animations, so at least skip those.
-      // FIXME: We'll need to handle this before using this for the
-      // transitions redesign.
-      continue;
+    dom::Element* elementToRestyle = collection->GetElementToRestyle();
+    if (elementToRestyle) {
+      nsRestyleHint rshint = collection->IsForTransitions()
+        ? eRestyle_CSSTransitions : eRestyle_CSSAnimations;
+      aTracker.AddPendingRestyle(elementToRestyle, rshint, nsChangeHint(0));
     }
-
-    nsRestyleHint rshint = collection->IsForTransitions()
-      ? eRestyle_CSSTransitions : eRestyle_CSSAnimations;
-    aTracker.AddPendingRestyle(collection->mElement, rshint, nsChangeHint(0));
   }
 }
 
@@ -413,6 +408,32 @@ AnimationPlayerCollection::HasAnimationOfProperty(
   return false;
 }
 
+mozilla::dom::Element*
+AnimationPlayerCollection::GetElementToRestyle() const
+{
+  if (IsForElement()) {
+    return mElement;
+  }
+
+  nsIFrame* primaryFrame = mElement->GetPrimaryFrame();
+  if (!primaryFrame) {
+    return nullptr;
+  }
+  nsIFrame* pseudoFrame;
+  if (IsForBeforePseudo()) {
+    pseudoFrame = nsLayoutUtils::GetBeforeFrame(primaryFrame);
+  } else if (IsForAfterPseudo()) {
+    pseudoFrame = nsLayoutUtils::GetAfterFrame(primaryFrame);
+  } else {
+    MOZ_ASSERT(false, "unknown mElementProperty");
+    return nullptr;
+  }
+  if (!pseudoFrame) {
+    return nullptr;
+  }
+  return pseudoFrame->GetContent()->AsElement();
+}
+
 /* static */ void
 AnimationPlayerCollection::LogAsyncAnimationFailure(nsCString& aMessage,
                                                      const nsIContent* aContent)

layout/style/AnimationCommon.h

@@ -230,6 +230,16 @@ struct AnimationPlayerCollection : public PRCList
            mElementProperty == nsGkAtoms::transitionsProperty;
   }
 
+  bool IsForBeforePseudo() const {
+    return mElementProperty == nsGkAtoms::animationsOfBeforeProperty ||
+           mElementProperty == nsGkAtoms::transitionsOfBeforeProperty;
+  }
+
+  bool IsForAfterPseudo() const {
+    return mElementProperty == nsGkAtoms::animationsOfAfterProperty ||
+           mElementProperty == nsGkAtoms::transitionsOfAfterProperty;
+  }
+
   bool IsForTransitions() const {
     return mElementProperty == nsGkAtoms::transitionsProperty ||
            mElementProperty == nsGkAtoms::transitionsOfBeforeProperty ||
@@ -246,14 +256,15 @@ struct AnimationPlayerCollection : public PRCList
   {
     if (IsForElement()) {
       return EmptyString();
-    } else if (mElementProperty == nsGkAtoms::animationsOfBeforeProperty ||
-               mElementProperty == nsGkAtoms::transitionsOfBeforeProperty) {
+    } else if (IsForBeforePseudo()) {
       return NS_LITERAL_STRING("::before");
     } else {
       return NS_LITERAL_STRING("::after");
     }
   }
 
+  mozilla::dom::Element* GetElementToRestyle() const;
+
   void PostRestyleForAnimation(nsPresContext *aPresContext) {
     nsRestyleHint styleHint = IsForElement() ? eRestyle_Self : eRestyle_Subtree;
     aPresContext->PresShell()->RestyleForAnimation(mElement, styleHint);