Animation: Cancel same-property animations on compositor

Source/core/animation/AnimationEffect.h

 /*
  * 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 36 matching lines @@
 public:
     enum CompositeOperation {
         CompositeReplace,
         CompositeAdd,
     };
 
     AnimationEffect() { }
     virtual ~AnimationEffect() { }
     virtual void sample(int iteration, double fraction, double iterationDuration, OwnPtrWillBeRawPtr<WillBeHeapVector<RefPtrWillBeMember<Interpolation>>>&) const = 0;
 
-    virtual bool affects(CSSPropertyID) { return false; };
+    virtual bool affects(CSSPropertyID) const { return false; };
     virtual bool isKeyframeEffectModel() const { return false; }
 
     virtual void trace(Visitor*) { }
 };
 
 } // namespace blink
 
 #endif // AnimationEffect_h