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

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 286 matching lines @@
         bool m_hasClip;
     };
 
     CanvasRenderingContext2D(HTMLCanvasElement*, const Canvas2DContextAttributes* attrs, bool usesCSSCompatibilityParseMode);
 
     State& modifiableState() { ASSERT(!state().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();
+    void applyShadow(ShadowMode = DrawShadowAndForeground);
     bool shouldDrawShadows() const;
 
     void dispatchContextLostEvent(Timer<CanvasRenderingContext2D>*);
     void dispatchContextRestoredEvent(Timer<CanvasRenderingContext2D>*);
     void tryRestoreContextEvent(Timer<CanvasRenderingContext2D>*);
 
     bool computeDirtyRect(const FloatRect& localBounds, FloatRect*);
     bool computeDirtyRect(const FloatRect& localBounds, const FloatRect& transformedClipBounds, FloatRect*);
     void didDraw(const FloatRect&);
 
@@ skipping 61 matching lines @@
     Timer<CanvasRenderingContext2D> m_dispatchContextLostEventTimer;
     Timer<CanvasRenderingContext2D> m_dispatchContextRestoredEventTimer;
     Timer<CanvasRenderingContext2D> m_tryRestoreContextEventTimer;
 };
 
 DEFINE_TYPE_CASTS(CanvasRenderingContext2D, CanvasRenderingContext, context, context->is2d(), context.is2d());
 
 } // namespace blink
 
 #endif // CanvasRenderingContext2D_h