Make PropertyHandle instances const references where possible

third_party/WebKit/Source/core/animation/EffectModel.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 40 matching lines @@
     CompositeAdd,
   };
 
   EffectModel() {}
   virtual ~EffectModel() {}
   virtual bool sample(int iteration,
                       double fraction,
                       double iterationDuration,
                       Vector<RefPtr<Interpolation>>&) const = 0;
 
-  virtual bool affects(PropertyHandle) const { return false; }
+  virtual bool affects(const PropertyHandle&) const { return false; }
   virtual bool isTransformRelatedEffect() const { return false; }
   virtual bool isKeyframeEffectModel() const { return false; }
 
   DEFINE_INLINE_VIRTUAL_TRACE() {}
 };
 
 }  // namespace blink
 
 #endif  // EffectModel_h