Add CSS property priority for CSS animation affecting properties

third_party/WebKit/Source/core/animation/css/CSSAnimations.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 826 matching lines @@
   for (const auto& entry : m_transitions) {
     entry.value.animation->cancel();
     entry.value.animation->update(TimingUpdateOnDemand);
   }
 
   m_runningAnimations.clear();
   m_transitions.clear();
   clearPendingUpdate();
 }
 
+// TODO(alancutter): CSS properties and presentation attributes may have
+// identical effects. By grouping them in the same set we introduce a bug where
+// arbitrary hash iteration will determine the order the apply in and thus which
+// one "wins". We should be more deliberate about the order of application in
+// the case of effect collisions.
+// Example: Both 'color' and 'svg-color' set the color on ComputedStyle but are
+// considered distinct properties in the ActiveInterpolationsMap.
 static bool isStylePropertyHandle(const PropertyHandle& propertyHandle) {
   return propertyHandle.isCSSProperty() ||
          propertyHandle.isPresentationAttribute();
 }
 
 void CSSAnimations::calculateAnimationActiveInterpolations(
     CSSAnimationUpdate& update,
     const Element* animatingElement) {
   ElementAnimations* elementAnimations =
       animatingElement ? animatingElement->elementAnimations() : nullptr;
@@ skipping 230 matching lines @@
   return toShadowRoot(treeScope.rootNode()).host() == element;
 }
 
 DEFINE_TRACE(CSSAnimations) {
   visitor->trace(m_transitions);
   visitor->trace(m_pendingUpdate);
   visitor->trace(m_runningAnimations);
 }
 
 }  // namespace blink