Remove support for -webkit-canvas and Document.getCSSCanvasContext.

third_party/WebKit/Source/core/xml/DocumentXMLTreeViewer.css

 /* Copyright 2014 The Chromium Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 div.header {
     border-bottom: 2px solid black;
     padding-bottom: 5px;
     margin: 10px;
 }
@@ skipping 25 matching lines @@
     cursor: pointer;
     display: inline-block;
     margin-left: -10px;
     width: 10px;
     background-repeat: no-repeat;
     background-position: left top;
     vertical-align: bottom;
 }
 
 .collapse-button {
-    background-image: -webkit-canvas(arrowDown);
+    background: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' fill='#909090' width='10' height='10'><path d='M0 0 L8 0 L4 7 Z'/></svg>");
     height: 10px;
 }
 
 .expand-button {
-    background-image: -webkit-canvas(arrowRight);
-    height: 11px;
+    background: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' fill='#909090' width='10' height='10'><path d='M0 0 L0 8 L7 4 Z'/></svg>");
+    height: 10px;
 }