Web Animations CSS: Support animation of {text,box,-webkit-box}-shadow and fix blur clamping

Source/core/rendering/style/ShadowData.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, 2009 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 30 matching lines @@
         , m_blur(blur)
         , m_spread(spread)
         , m_color(color)
         , m_style(style)
     {
     }
 
     bool operator==(const ShadowData&) const;
     bool operator!=(const ShadowData& o) const { return !(*this == o); }
 
+    ShadowData blend(const ShadowData& from, double progress) const;
+
     int x() const { return m_location.x(); }
     int y() const { return m_location.y(); }
     IntPoint location() const { return m_location; }
     int blur() const { return m_blur; }
     int spread() const { return m_spread; }
     ShadowStyle style() const { return m_style; }
     const Color& color() const { return m_color; }
 
 private:
     IntPoint m_location;
     int m_blur;
     int m_spread;
     Color m_color;
     ShadowStyle m_style;
 };
 
 } // namespace WebCore
 
 #endif // ShadowData_h