Remove some unused functions in core

Source/core/animation/animatable/AnimatableColor.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 25 matching lines @@
 
 namespace blink {
 
 class AnimatableColorImpl {
 public:
     AnimatableColorImpl(float red, float green, float blue, float alpha);
     AnimatableColorImpl(Color);
     Color toColor() const;
     AnimatableColorImpl interpolateTo(const AnimatableColorImpl&, double fraction) const;
     bool operator==(const AnimatableColorImpl&) const;
-    double distanceTo(const AnimatableColorImpl&) const;
 
 private:
     float m_alpha;
     float m_red;
     float m_green;
     float m_blue;
 };
 
 // This class handles both the regular and 'visted link' colors for a given
 // property. Currently it is used for all properties, even those which do not
@@ skipping 11 matching lines @@
     virtual PassRefPtrWillBeRawPtr<AnimatableValue> interpolateTo(const AnimatableValue*, double fraction) const override;
 
 private:
     AnimatableColor(const AnimatableColorImpl& color, const AnimatableColorImpl& visitedLinkColor)
         : m_color(color)
         , m_visitedLinkColor(visitedLinkColor)
     {
     }
     virtual AnimatableType type() const override { return TypeColor; }
     virtual bool equalTo(const AnimatableValue*) const override;
-    virtual double distanceTo(const AnimatableValue*) const override;
     const AnimatableColorImpl m_color;
     const AnimatableColorImpl m_visitedLinkColor;
 };
 
 DEFINE_ANIMATABLE_VALUE_TYPE_CASTS(AnimatableColor, isColor());
 
 } // namespace blink
 
 #endif // AnimatableColor_h