Introduce toHTMLCanvasElement

Source/core/inspector/InspectorCanvasAgent.cpp

 /*
  * Copyright (C) 2012 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 261 matching lines @@
 
         virtual void visitNode(Node* node) OVERRIDE
         {
             if (!node->hasTagName(HTMLNames::canvasTag) || !node->document() || !node->document()->frame())
                 return;
             
             Frame* frame = node->document()->frame();
             if (frame->page() != m_page)
                 return;
 
-            HTMLCanvasElement* canvas = static_cast<HTMLCanvasElement*>(node);
-            if (canvas->renderingContext())
+            if (toHTMLCanvasElement(node)->renderingContext())
                 m_framesWithUninstrumentedCanvases.set(frame, true);
         }
 
     private:
         Page* m_page;
         FramesWithUninstrumentedCanvases& m_framesWithUninstrumentedCanvases;
     } nodeVisitor(m_pageAgent->page(), m_framesWithUninstrumentedCanvases);
 
     m_framesWithUninstrumentedCanvases.clear();
     ScriptProfiler::visitNodeWrappers(&nodeVisitor);
@@ skipping 50 matching lines @@
     ErrorString error;
     for (FramesWithUninstrumentedCanvases::iterator it = m_framesWithUninstrumentedCanvases.begin(); it != m_framesWithUninstrumentedCanvases.end(); ++it) {
         InjectedScriptCanvasModule module = injectedScriptCanvasModule(&error, mainWorldScriptState(it->key));
         if (!module.hasNoValue())
             module.markFrameEnd();
     }
 }
 
 } // namespace WebCore