Re-land "WebGL: Transfer ownership of WebGraphicsContext3D to DrawingBuffer"

Source/core/html/canvas/WebGLRenderbuffer.cpp

 /*
  * Copyright (C) 2009 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 31 matching lines @@
 }
 
 WebGLRenderbuffer::WebGLRenderbuffer(WebGLRenderingContextBase* ctx)
     : WebGLSharedObject(ctx)
     , m_internalFormat(GL_RGBA4)
     , m_width(0)
     , m_height(0)
     , m_hasEverBeenBound(false)
 {
     ScriptWrappable::init(this);
-    setObject(ctx->webGraphicsContext3D()->createRenderbuffer());
+    setObject(ctx->webContext()->createRenderbuffer());
 }
 
 void WebGLRenderbuffer::deleteObjectImpl(blink::WebGraphicsContext3D* context3d, Platform3DObject object)
 {
     context3d->deleteRenderbuffer(object);
     deleteEmulatedStencilBuffer(context3d);
 }
 
 void WebGLRenderbuffer::deleteEmulatedStencilBuffer(blink::WebGraphicsContext3D* context3d)
 {
     if (!m_emulatedStencilBuffer)
         return;
     m_emulatedStencilBuffer->deleteObject(context3d);
     m_emulatedStencilBuffer.clear();
 }
 
 }