GraphicsContext culling support.

Source/platform/graphics/GraphicsContext.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  * Copyright (C) 2013 Google 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.
@@ skipping 287 matching lines @@
     enum DocumentMarkerLineStyle {
         DocumentMarkerSpellingLineStyle,
         DocumentMarkerGrammarLineStyle
     };
     void drawLineForDocumentMarker(const FloatPoint&, float width, DocumentMarkerLineStyle);
 
     void beginTransparencyLayer(float opacity, const FloatRect* = 0);
     void beginLayer(float opacity, CompositeOperator, const FloatRect* = 0, ColorFilter = ColorFilterNone, ImageFilter* = 0);
     void endLayer();
 
+    void beginCull(const FloatRect&);
+    void endCull();
+
     // Instead of being dispatched to the active canvas, draw commands following beginRecording()
     // are stored in a display list that can be replayed at a later time.
     void beginRecording(const FloatRect& bounds);
     PassRefPtr<DisplayList> endRecording();
 
     bool hasShadow() const;
     void setShadow(const FloatSize& offset, float blur, const Color&,
         DrawLooperBuilder::ShadowTransformMode = DrawLooperBuilder::ShadowRespectsTransforms,
         DrawLooperBuilder::ShadowAlphaMode = DrawLooperBuilder::ShadowRespectsAlpha);
     void clearShadow() { clearDrawLooper(); }
@@ skipping 183 matching lines @@
     // FIXME: Make this go away: crbug.com/236892
     bool m_updatingControlTints : 1;
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
 };
 
 } // namespace WebCore
 
 #endif // GraphicsContext_h