Implement "Save image as" for canvas (blink side).

Source/core/rendering/HitTestResult.cpp

 /*
  * Copyright (C) 2006, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 261 matching lines @@
     if (!image())
         return IntRect();
     return m_innerNonSharedNode->renderBox()->absoluteContentQuad().enclosingBoundingBox();
 }
 
 KURL HitTestResult::absoluteImageURL() const
 {
     if (!m_innerNonSharedNode)
         return KURL();
 
-    if (!(m_innerNonSharedNode->renderer() && m_innerNonSharedNode->renderer()->isImage()))
+    RenderObject* renderer = m_innerNonSharedNode->renderer();
+    if (!(renderer && (renderer->isImage() || renderer->isCanvas())))
         return KURL();
 
     AtomicString urlString;
-    if (isHTMLEmbedElement(*m_innerNonSharedNode)
+    if (isHTMLCanvasElement(*m_innerNonSharedNode)
+        || isHTMLEmbedElement(*m_innerNonSharedNode)
         || isHTMLImageElement(*m_innerNonSharedNode)
         || isHTMLInputElement(*m_innerNonSharedNode)
         || isHTMLObjectElement(*m_innerNonSharedNode)
         || isSVGImageElement(*m_innerNonSharedNode)
        ) {
         urlString = toElement(*m_innerNonSharedNode).imageSourceURL();
     } else
         return KURL();
 
     return m_innerNonSharedNode->document().completeURL(stripLeadingAndTrailingHTMLSpaces(urlString));
@@ skipping 188 matching lines @@
 {
     for (Node* node = m_innerNode.get(); node; node = NodeRenderingTraversal::parent(node)) {
         if (node->isElementNode())
             return toElement(node);
     }
 
     return 0;
 }
 
 } // namespace WebCore