Implement basic parts of hit regions on canvas2d.

Source/core/accessibility/AXObjectCache.cpp

 /*
  * Copyright (C) 2008, 2009, 2010 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
@@ skipping 1000 matching lines @@
 void AXObjectCache::handleScrollPositionChanged(ScrollView* scrollView)
 {
     postPlatformNotification(getOrCreate(scrollView), AXScrollPositionChanged);
 }
 
 void AXObjectCache::handleScrollPositionChanged(RenderObject* renderObject)
 {
     postPlatformNotification(getOrCreate(renderObject), AXScrollPositionChanged);
 }
 
+void AXObjectCache::setCanvasObjectBounds(Element* element, const LayoutRect& rect)
+{
+    AXObject* obj = getOrCreate(element);
+    if (!obj)
+        return;
+
+    obj->setElementRect(rect);
+}
+
 } // namespace WebCore