Fixed Shadow blur for transparent objects

Source/platform/graphics/GraphicsContextState.h

Index: Source/platform/graphics/GraphicsContextState.h
diff --git a/Source/platform/graphics/GraphicsContextState.h b/Source/platform/graphics/GraphicsContextState.h
index 9dbbcfc305e26c424a23ca8640dbad486ae8027f..acfe0a076c139bcca9044497c8b01d5522c18783 100644
--- a/Source/platform/graphics/GraphicsContextState.h
+++ b/Source/platform/graphics/GraphicsContextState.h
@@ -36,6 +36,7 @@
 #include "platform/graphics/Pattern.h"
 #include "platform/graphics/StrokeData.h"
 #include "third_party/skia/include/core/SkColorFilter.h"
+#include "third_party/skia/include/core/SkImageFilter.h"
 #include "third_party/skia/include/core/SkPaint.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefPtr.h"
@@ -110,6 +111,10 @@ public:
     void setDrawLooper(PassRefPtr<SkDrawLooper>);
     void clearDrawLooper();
 
+    SkImageFilter* dropShadowImageFilter() const { return m_dropShadowImageFilter.get(); }
+    void setDropShadowImageFilter(PassRefPtr<SkImageFilter>);
+    void clearDropShadowImageFilter();
+
     // Text. (See TextModeFill & friends.)
     TextDrawingModeFlags textDrawingMode() const { return m_textDrawingMode; }
     void setTextDrawingMode(TextDrawingModeFlags mode) { m_textDrawingMode = mode; }
@@ -165,6 +170,7 @@ private:
     RefPtr<Pattern> m_fillPattern;
 
     RefPtr<SkDrawLooper> m_looper;
+    RefPtr<SkImageFilter> m_dropShadowImageFilter;
 
     TextDrawingModeFlags m_textDrawingMode;