Remove width and height attributes of CanvasRenderingContext2D

These attributes are remnants of the CanvasProxy feature, which
was removed from the spec.  There are no known implementations
of these attributes. They are currently completely redundant
with the attributes of the same names on canvas elements.

source

@@ -60386,10 +60386,6 @@ enum <dfn>ImageSmoothingQuality</dfn> { "<span data-x="dom-context-2d-imageSmoot
 interface <dfn>CanvasRenderingContext2D</dfn> {
   // back-reference to the canvas
   readonly attribute <span>HTMLCanvasElement</span> <span data-x="dom-context-2d-canvas">canvas</span>;
-
-  // canvas dimensions
-  attribute unsigned long <span data-x="dom-context-2d-width">width</span>;
-  attribute unsigned long <span data-x="dom-context-2d-height">height</span>;
 };
 <span>CanvasRenderingContext2D</span> implements <span>CanvasState</span>;
 <span>CanvasRenderingContext2D</span> implements <span>CanvasTransform</span>;
@@ -60692,18 +60688,6 @@ interface <dfn>Path2D</dfn> {
 
    </dd>
 
-   <dt><var>context</var> . <code subdfn data-x="dom-context-2d-width">width</code></dt>
-   <dt><var>context</var> . <code subdfn data-x="dom-context-2d-height">height</code></dt>
-
-   <dd>
-
-    <p>Return the dimensions of the bitmap, in <span data-x="'px'">CSS pixels</span>.</p>
-
-    <p>Can be set, to update the bitmap's dimensions. This will also update the canvas's
-    <span>intrinsic dimensions</span>.</p>
-
-   </dd>
-
   </dl>
 
   <div w-nodev>
@@ -60919,19 +60903,6 @@ context.fillRect(100,0,50,50); // only this square remains</pre>
   <p>The <dfn><code data-x="dom-context-2d-canvas">canvas</code></dfn> attribute must return the
   value it was initialised to when the object was created.</p>
 
-  <p>The <dfn><code data-x="dom-context-2d-width">width</code></dfn> attribute, on getting, must
-  return the width of the rendering context's <span>output bitmap</span>, in <span data-x="'px'">CSS
-  pixels</span>. On setting, it must <span data-x="concept-canvas-set-bitmap-dimensions">set bitmap
-  dimensions</span> to the new value and the current height of the rendering context's <span>output
-  bitmap</span> in <span data-x="'px'">CSS pixels</span>, respectively.</p>
-
-  <p>The <dfn><code data-x="dom-context-2d-height">height</code></dfn> attribute, on getting, must
-  return the height of the rendering context's <span>output bitmap</span>, in <span
-  data-x="'px'">CSS pixels</span>. On setting, it must <span
-  data-x="concept-canvas-set-bitmap-dimensions">set bitmap dimensions</span> to the current width of
-  the rendering context's <span>output bitmap</span> in <span data-x="'px'">CSS pixels</span> and
-  the new value, respectively.</p>
-
   <hr>
 
   <p>Except where otherwise specified, for the 2D context interface, <strong>any method call with a