Bug 1226118 part 9 - Use EffectCompositor::GetAnimationsForCompositor in nsDisplayList; r=dholbert

The existing code contains a comment about needing to add transitions before
animations. However, this is unnecessary since the interaction between
transitions and animations is handled by the mWinsInCascade member that is
checked in AddAnimationsForProperty.

layout/base/nsDisplayList.cpp

@@ -55,6 +55,7 @@
 #include "nsCanvasFrame.h"
 #include "StickyScrollContainer.h"
 #include "mozilla/AnimationUtils.h"
+#include "mozilla/EffectCompositor.h"
 #include "mozilla/EventStates.h"
 #include "mozilla/LookAndFeel.h"
 #include "mozilla/PendingAnimationTracker.h"
@@ -528,13 +529,9 @@ nsDisplayListBuilder::AddAnimationsAndTransitionsToLayer(Layer* aLayer,
                                                                aProperty);
   presContext->AnimationManager()->ClearIsRunningOnCompositor(aFrame,
                                                               aProperty);
-  AnimationCollection* transitions =
-    presContext->TransitionManager()->GetAnimationsForCompositor(aFrame,
-                                                                 aProperty);
-  AnimationCollection* animations =
-    presContext->AnimationManager()->GetAnimationsForCompositor(aFrame,
-                                                                aProperty);
-  if (!animations && !transitions) {
+  nsTArray<RefPtr<dom::Animation>> compositorAnimations =
+    EffectCompositor::GetAnimationsForCompositor(aFrame, aProperty);
+  if (compositorAnimations.IsEmpty()) {
     return;
   }
 
@@ -590,17 +587,8 @@ nsDisplayListBuilder::AddAnimationsAndTransitionsToLayer(Layer* aLayer,
     data = null_t();
   }
 
-  // When both are running, animations override transitions.  We want
-  // to add the ones that override last.
-  if (transitions) {
-    AddAnimationsForProperty(aFrame, aProperty, transitions->mAnimations,
-                             aLayer, data, pending);
-  }
-
-  if (animations) {
-    AddAnimationsForProperty(aFrame, aProperty, animations->mAnimations,
-                             aLayer, data, pending);
-  }
+  AddAnimationsForProperty(aFrame, aProperty, compositorAnimations,
+                           aLayer, data, pending);
 }
 
 nsDisplayListBuilder::nsDisplayListBuilder(nsIFrame* aReferenceFrame,