Fixed Shadow blur for transparent objects

Source/platform/graphics/UnacceleratedImageBufferSurface.cpp

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 20 matching lines @@
 #include "config.h"
 #include "platform/graphics/UnacceleratedImageBufferSurface.h"
 
 #include "third_party/skia/include/core/SkSurface.h"
 #include "wtf/PassRefPtr.h"
 
 namespace blink {
 
 UnacceleratedImageBufferSurface::UnacceleratedImageBufferSurface(const IntSize& size, OpacityMode opacityMode)
     : ImageBufferSurface(size, opacityMode)
-    , m_surface(adoptRef(SkSurface::NewRasterPMColor(size.width(), size.height())))
 {
+    SkAlphaType alphaType = (Opaque == opacityMode) ? kOpaque_SkAlphaType : kPremul_SkAlphaType;
+    SkImageInfo info = SkImageInfo::MakeN32(size.width(), size.height(), alphaType);
+    m_surface = adoptRef(SkSurface::NewRaster(info));
+
     if (m_surface)
         clear();
 }
 
 UnacceleratedImageBufferSurface::~UnacceleratedImageBufferSurface() { }
 
 SkCanvas* UnacceleratedImageBufferSurface::canvas() const
 {
     return m_surface->getCanvas();
 }
 
 bool UnacceleratedImageBufferSurface::isValid() const
 {
     return m_surface;
 }
 
 PassRefPtr<SkImage> UnacceleratedImageBufferSurface::newImageSnapshot() const
 {
     return adoptRef(m_surface->newImageSnapshot());
 }
 
 } // namespace blink