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

Source/platform/graphics/ImageBufferSurface.h

Index: Source/platform/graphics/ImageBufferSurface.h
diff --git a/Source/platform/graphics/ImageBufferSurface.h b/Source/platform/graphics/ImageBufferSurface.h
index d67fb33cee519cd751d8c1048f76ed0484a90362..90df53e89df8b1b813372eea6f8209de33a9c8d4 100644
--- a/Source/platform/graphics/ImageBufferSurface.h
+++ b/Source/platform/graphics/ImageBufferSurface.h
@@ -34,6 +34,7 @@
 #include "platform/PlatformExport.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/GraphicsTypes3D.h"
+#include "third_party/skia/include/core/SkPaint.h"
 #include "wtf/FastAllocBase.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PassRefPtr.h"
@@ -73,6 +74,7 @@ public:
     virtual const SkBitmap& cachedBitmap() const;
     virtual void invalidateCachedBitmap() { }
     virtual void updateCachedBitmapIfNeeded() { }
+    virtual void setFilterLevel(SkPaint::FilterLevel) { }
     virtual void setIsHidden(bool) { }
     virtual void setImageBuffer(ImageBuffer*) { }
     virtual PassRefPtr<SkPicture> getPicture();