Use SkImage as a backing store for copying 2d Contexts to ImageBitmaps.

Source/core/html/canvas/CanvasRenderingContext2D.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011, 2012 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 265 matching lines @@
     CanvasRenderingContext2D(HTMLCanvasElement*, const Canvas2DContextAttributes* attrs, bool usesCSSCompatibilityParseMode);
 
     State& modifiableState() { ASSERT(!m_unrealizedSaveCount); return m_stateStack.last(); }
     const State& state() const { return m_stateStack.last(); }
 
     void applyLineDash() const;
     void setShadow(const FloatSize& offset, float blur, RGBA32 color);
     void applyShadow();
     bool shouldDrawShadows() const;
 
-    void drawImageInternal(Image*, const FloatRect&, const FloatRect&, const CompositeOperator&, const BlendMode&);
+    template<class T> void drawImageInternal(T*, const FloatRect&, const FloatRect&, const CompositeOperator&, const BlendMode&);
     void didDraw(const FloatRect&, unsigned options = CanvasDidDrawApplyAll);
     void didDrawEntireCanvas();
 
     GraphicsContext* drawingContext() const;
 
     void unwindStateStack();
     void realizeSaves()
     {
         if (m_unrealizedSaveCount)
             realizeSavesLoop();
@@ skipping 35 matching lines @@
     Vector<State, 1> m_stateStack;
     unsigned m_unrealizedSaveCount;
     bool m_usesCSSCompatibilityParseMode;
     bool m_hasAlpha;
     MutableStylePropertyMap m_cachedFonts;
 };
 
 } // namespace WebCore
 
 #endif