Implement image-rendering:pixelated for accelerated 2D canvases.

Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 151 matching lines @@
     virtual void trace(Visitor*) override;
 
 protected:
     virtual void didMoveToNewDocument(Document& oldDocument) override;
 
 private:
     explicit HTMLCanvasElement(Document&);
 
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;
     virtual RenderObject* createRenderer(RenderStyle*) override;
+    virtual void didRecalcStyle(StyleRecalcChange) override;
     virtual bool areAuthorShadowsAllowed() const override { return false; }
 
     void reset();
 
     PassOwnPtr<RecordingImageBufferFallbackSurfaceFactory> createSurfaceFactory(const IntSize& deviceSize, int* msaaSampleCount) const;
     PassOwnPtr<ImageBufferSurface> createImageBufferSurface(const IntSize& deviceSize, int* msaaSampleCount);
     void createImageBuffer();
     void createImageBufferInternal();
     bool shouldUseDisplayList(const IntSize& deviceSize);
 
@@ skipping 27 matching lines @@
     bool m_imageBufferIsClear;
     OwnPtr<ImageBuffer> m_imageBuffer;
     mutable OwnPtr<GraphicsContextStateSaver> m_contextStateSaver;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h