Make WebGL extensions get lost when context is lost.

Source/core/html/canvas/WebGLDebugShaders.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
@@ skipping 10 matching lines @@
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef WebGLDebugShaders_h
 #define WebGLDebugShaders_h
 
 #include "bindings/v8/ScriptWrappable.h"
 #include "core/html/canvas/WebGLExtension.h"
-#include "wtf/PassOwnPtr.h"
+#include "wtf/PassRefPtr.h"
 
 namespace WebCore {
 
 class WebGLShader;
 
 typedef int ExceptionCode;
 
 class WebGLDebugShaders : public WebGLExtension, public ScriptWrappable {
 public:
-    static PassOwnPtr<WebGLDebugShaders> create(WebGLRenderingContext*);
+    static PassRefPtr<WebGLDebugShaders> create(WebGLRenderingContext*);
     static bool supported(WebGLRenderingContext*);
     static const char* getExtensionName();
 
     virtual ~WebGLDebugShaders();
     virtual ExtensionName getName() const;
 
     String getTranslatedShaderSource(WebGLShader*, ExceptionCode&);
 
 private:
     WebGLDebugShaders(WebGLRenderingContext*);
 };
 
 } // namespace WebCore
 
 #endif // WebGLDebugShaders_h