Creating a helper class for reversing timing functions.

Source/core/platform/animation/TimingFunction.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 263 matching lines @@
         }
 
     private:
         double scaleToLocal(double x) const { return (x - m_min) / (m_max - m_min); }
         double scaleFromLocal(double x) const { return blend(m_min, m_max, x); }
 
         double m_min;
         double m_max;
         RefPtr<TimingFunction> m_timingFunction;
 
+        // Allow the compositor to reverse the timing function.
+        friend class CompositorAnimationsTimingFunctionReverser;
+
         // Allow PrintTo/operator== of the segments. Can be removed once
         // ChainedTimingFunction has a public API for segments.
         friend class ChainedTimingFunctionTestHelper;
     };
 
     ChainedTimingFunction()
         : TimingFunction(ChainedFunction)
     {
         ASSERT(RuntimeEnabledFeatures::webAnimationsEnabled());
     }
 
     Vector<Segment> m_segments;
 
+    // Allow the compositor to reverse the timing function.
+    friend class CompositorAnimationsTimingFunctionReverser;
+
     // Allow PrintTo/operator== of the segments. Can be removed once
     // ChainedTimingFunction has a public API for segments.
     friend class ChainedTimingFunctionTestHelper;
 };
 
 } // namespace WebCore
 
 #endif // TimingFunction_h