Fix copyImage for WebGL elements.

Source/core/html/HTMLCanvasElement.cpp

 /*
  * Copyright (C) 2004, 2006, 2007 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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 574 matching lines @@
         return;
     discardImageBuffer();
     OpacityMode opacityMode = !m_context || m_context->hasAlpha() ? NonOpaque : Opaque;
     m_imageBuffer = ImageBuffer::create(size(), opacityMode);
     m_didFailToCreateImageBuffer = !m_imageBuffer;
 }
 
 Image* HTMLCanvasElement::copiedImage() const
 {
     if (!m_copiedImage && buffer()) {
-        if (m_context)
+        if (m_context && m_context->is3d()) {
+            toWebGLRenderingContext(m_context.get())->setSavingImage(true);
             m_context->paintRenderingResultsToCanvas();
+            toWebGLRenderingContext(m_context.get())->setSavingImage(false);
+        }
         m_copiedImage = buffer()->copyImage(CopyBackingStore, Unscaled);
         updateExternallyAllocatedMemory();
     }
     return m_copiedImage.get();
 }
 
 void HTMLCanvasElement::clearImageBuffer()
 {
     ASSERT(hasImageBuffer() && !m_didFailToCreateImageBuffer);
     ASSERT(!m_didClearImageBuffer);
@@ skipping 85 matching lines @@
 {
     return !originClean();
 }
 
 FloatSize HTMLCanvasElement::sourceSize() const
 {
     return FloatSize(width(), height());
 }
 
 }