2D canvas: fix shadow rendering with compositing modes that require temp layers

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 334 matching lines @@
 
     // 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. Pass in the bounding
     // rectangle for the content in the list.
     void beginRecording(const FloatRect&, uint32_t = 0);
     PassRefPtr<DisplayList> endRecording();
 
     bool hasShadow() const;
     void setShadow(const FloatSize& offset, float blur, const Color&,
         DrawLooperBuilder::ShadowTransformMode = DrawLooperBuilder::ShadowRespectsTransforms,
-        DrawLooperBuilder::ShadowAlphaMode = DrawLooperBuilder::ShadowRespectsAlpha);
+        DrawLooperBuilder::ShadowAlphaMode = DrawLooperBuilder::ShadowRespectsAlpha, ShadowMode = DrawShadowAndForeground);
     void clearShadow() { clearDrawLooper(); }
 
     // It is assumed that this draw looper is used only for shadows
     // (i.e. a draw looper is set if and only if there is a shadow).
     // The builder passed into this method will be destroyed.
     void setDrawLooper(PassOwnPtr<DrawLooperBuilder>);
     void clearDrawLooper();
 
     void drawFocusRing(const Vector<IntRect>&, int width, int offset, const Color&);
     void drawFocusRing(const Path&, int width, int offset, const Color&);
@@ skipping 175 matching lines @@
     bool m_accelerated : 1;
     bool m_isCertainlyOpaque : 1;
     bool m_printing : 1;
     bool m_antialiasHairlineImages : 1;
     bool m_shouldSmoothFonts : 1;
 };
 
 } // namespace blink
 
 #endif // GraphicsContext_h