Remove CanvasRenderingContext from the web exposed objects

Source/core/html/canvas/CanvasRenderingContext2D.idl

 /*
  * Copyright (C) 2006 Apple Computer, 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
  *    documentation and/or other materials provided with the distribution.
  *
  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 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.
  */
 
 enum CanvasWindingRule { "nonzero", "evenodd" };
 
-interface CanvasRenderingContext2D : CanvasRenderingContext {
+interface CanvasRenderingContext2D {
+
+    readonly attribute HTMLCanvasElement canvas;
 
     void save();
     void restore();
 
     [StrictTypeChecking, RuntimeEnabled=ExperimentalCanvasFeatures, RaisesException=Setter] attribute SVGMatrix currentTransform;
     void scale(float sx, float sy);
     void rotate(float angle);
     void translate(float tx, float ty);
     void transform(float m11, float m12, float m21, float m22, float dx, float dy);
     void setTransform(float m11, float m12, float m21, float m22, float dx, float dy);
@@ skipping 133 matching lines @@
     [RuntimeEnabled=ExperimentalCanvasFeatures] boolean drawCustomFocusRing(Element element);
 
     readonly attribute float webkitBackingStorePixelRatio;
 
     [ImplementedAs=imageSmoothingEnabled, MeasureAs=PrefixedImageSmoothingEnabled] attribute boolean webkitImageSmoothingEnabled;
     [MeasureAs=UnprefixedImageSmoothingEnabled] attribute boolean imageSmoothingEnabled;
 
     Canvas2DContextAttributes getContextAttributes();
 };