Make WebGL extensions get lost when context is lost.

Source/core/html/canvas/OESVertexArrayObject.h

 /*
  * Copyright (C) 2011 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:
  * 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 12 matching lines @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
  */
 
 #ifndef OESVertexArrayObject_h
 #define OESVertexArrayObject_h
 
 #include "bindings/v8/ScriptWrappable.h"
 #include "core/html/canvas/WebGLExtension.h"
 #include "core/html/canvas/WebGLVertexArrayObjectOES.h"
 #include "core/platform/graphics/GraphicsTypes3D.h"
-#include "wtf/PassOwnPtr.h"
+#include "wtf/PassRefPtr.h"
 #include "wtf/UnusedParam.h"
 
 namespace WebCore {
 
 class WebGLRenderingContext;
 class WebGLVertexArrayObjectOES;
 
 typedef int ExceptionCode;
 
 class OESVertexArrayObject : public WebGLExtension, public ScriptWrappable {
 public:
-    static PassOwnPtr<OESVertexArrayObject> create(WebGLRenderingContext*);
+    static PassRefPtr<OESVertexArrayObject> create(WebGLRenderingContext*);
     static bool supported(WebGLRenderingContext*);
     static const char* getExtensionName();
 
     virtual ~OESVertexArrayObject();
     virtual ExtensionName getName() const;
 
     PassRefPtr<WebGLVertexArrayObjectOES> createVertexArrayOES();
     void deleteVertexArrayOES(WebGLVertexArrayObjectOES*);
     GC3Dboolean isVertexArrayOES(WebGLVertexArrayObjectOES*);
     void bindVertexArrayOES(WebGLVertexArrayObjectOES*, ExceptionCode&);
 
 private:
     OESVertexArrayObject(WebGLRenderingContext*);
 };
 
 } // namespace WebCore
 
 #endif // OESVertexArrayObject_h