Bug 1355758 - Update RestyleManager::mAnimationGeneration for non-animation update. r=heycam

We use RestyleManager::mAnimationGeneration as the animation index of a
new created transition, and Element.getAnimations() uses this index to
sort the order of transitions. We increase mAnimationGeneration one per
restyle cycle if there is any non-animation update.

MozReview-Commit-ID: KmirBzI7CXi

--HG--
extra : rebase_source : 6a9001ea99f86c25b1d8d0a822b51b8753248bfb

layout/base/ServoRestyleManager.cpp

@@ -55,6 +55,10 @@ ServoRestyleManager::PostRestyleEvent(Element* aElement,
     return;
   }
 
+  if (aRestyleHint & ~eRestyle_AllHintsWithAnimations) {
+    mHaveNonAnimationRestyles = true;
+  }
+
   Servo_NoteExplicitHints(aElement, aRestyleHint, aMinChangeHint);
 }
 
@@ -71,6 +75,8 @@ ServoRestyleManager::RebuildAllStyleData(nsChangeHint aExtraHint,
 {
   StyleSet()->RebuildData();
 
+  mHaveNonAnimationRestyles = true;
+
   // NOTE(emilio): GeckoRestlyeManager does a sync style flush, which seems
   // not to be needed in my testing.
   //
@@ -387,6 +393,9 @@ ServoRestyleManager::ProcessPendingRestyles()
   // in a loop because certain rare paths in the frame constructor (like
   // uninstalling XBL bindings) can trigger additional style validations.
   mInStyleRefresh = true;
+  if (mHaveNonAnimationRestyles) {
+    ++mAnimationGeneration;
+  }
   while (styleSet->StyleDocument()) {
     // Recreate style contexts, and queue up change hints (which also handle
     // lazy frame construction).
@@ -419,6 +428,7 @@ ServoRestyleManager::ProcessPendingRestyles()
 
   FlushOverflowChangedTracker();
 
+  mHaveNonAnimationRestyles = false;
   mInStyleRefresh = false;
   styleSet->AssertTreeIsClean();
 

layout/base/ServoRestyleManager.h

@@ -148,6 +148,13 @@ private:
   // Only non-null while processing change hints. See the comment in
   // ProcessPendingRestyles.
   ReentrantChangeList* mReentrantChanges;
+
+  // We use this flag to track if the current restyle contains any non-animation
+  // update, which triggers a normal restyle, and so there might be any new
+  // transition created later. Therefore, if this flag is true, we need to
+  // increase mAnimationGeneration before creating new transitions, so their
+  // creation sequence will be correct.
+  bool mHaveNonAnimationRestyles = false;
 };
 
 } // namespace mozilla