Implement basic parts of hit regions on canvas2d.

Source/core/accessibility/AXObjectCache.h

 /*
  * Copyright (C) 2003, 2006, 2007, 2008, 2009, 2010, 2011 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 179 matching lines @@
         AXTextRemoved,
         AXValueChanged
     };
 
     void postNotification(RenderObject*, AXNotification, bool postToElement, PostType = PostAsynchronously);
     void postNotification(Node*, AXNotification, bool postToElement, PostType = PostAsynchronously);
     void postNotification(AXObject*, Document*, AXNotification, bool postToElement, PostType = PostAsynchronously);
 
     bool nodeHasRole(Node*, const AtomicString& role);
 
+    void setCanvasObjectBounds(Element*, const LayoutRect&);
+
     AXComputedObjectAttributeCache* computedObjectAttributeCache() { return m_computedObjectAttributeCache.get(); }
 
 protected:
     void postPlatformNotification(AXObject*, AXNotification);
     void textChanged(AXObject*);
     void labelChanged(Element*);
 
     // This is a weak reference cache for knowing if Nodes used by TextMarkers are valid.
     void setNodeInUse(Node* n) { m_textMarkerNodes.add(n); }
     void removeNodeForUse(Node* n) { m_textMarkerNodes.remove(n); }
@@ skipping 22 matching lines @@
     AXID getAXID(AXObject*);
 };
 
 bool nodeHasRole(Node*, const String& role);
 // This will let you know if aria-hidden was explicitly set to false.
 bool isNodeAriaVisible(Node*);
 
 }
 
 #endif