Get rid of ObjectElement#svgDocument.

client/html/src/ObjectElement.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 interface ObjectElement extends Element {
 
   String get align();
 
   void set align(String value);
 
@@ skipping 64 matching lines @@
   String get width();
 
   void set width(String value);
 
   bool get willValidate();
 
   bool checkValidity();
 
   void setCustomValidity(String error);
 
-  SVGDocument get svgDocument();
+  // Don't support getSVGDocument because the content document won't have all
+  // the necessary patches to the prototype hierarchy under Frog.
 }