Implement WEBGL_shared_resources

Source/core/html/canvas/WebGLExtension.h

 /*
  * Copyright (C) 2010 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 36 matching lines @@
         OESTextureHalfFloatName,
         OESVertexArrayObjectName,
         WebGLCompressedTextureATCName,
         WebGLCompressedTexturePVRTCName,
         WebGLCompressedTextureS3TCName,
         WebGLDebugRendererInfoName,
         WebGLDebugShadersName,
         WebGLDepthTextureName,
         WebGLDrawBuffersName,
         WebGLLoseContextName,
+        WebGLSharedResourcesName,
     };
 
     WebGLRenderingContext* context() { return m_context; }
 
     virtual ~WebGLExtension();
     virtual ExtensionName getName() const = 0;
 
     // Lose this extension. Passing true = force loss. Some extensions
     // like WEBGL_lose_context are not normally lost when the context
     // is lost but must be lost when destroying their WebGLRenderingContext.
     virtual void lose(bool)
     {
         m_context = 0;
     }
 
-    bool isLost()
+    bool isLost() const
     {
         return !m_context;
     }
 
 protected:
     WebGLExtension(WebGLRenderingContext*);
 
     WebGLRenderingContext* m_context;
 };
 
 } // namespace WebCore
 
 #endif // WebGLExtension_h