Include DDC fixes to dart:html in the main version

tools/dom/templates/html/impl/impl_SVGElement.darttemplate

 // 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.
 
 part of $LIBRARYNAME;
 
 class AttributeClassSet extends CssClassSetImpl {
   final Element _element;
 
   AttributeClassSet(this._element);
 
   Set<String> readClasses() {
     var classname = _element.attributes['class'];
     if (classname is AnimatedString) {
-      classname = classname.baseVal;
+      classname = (classname as AnimatedString).baseVal;
     }
 
     Set<String> s = new LinkedHashSet<String>();
     if (classname == null) {
       return s;
     }
     for (String name in classname.split(' ')) {
       String trimmed = name.trim();
       if (!trimmed.isEmpty) {
         s.add(trimmed);
@@ skipping 121 matching lines @@
     return e is $CLASSNAME && !(e is UnknownElement);
   }
 
 $if JSINTEROP
   set _svgClassName(AnimatedString value) =>
       _blink.BlinkSVGElement.instance.className_Setter_(this, value);
 
 $endif
 $!MEMBERS
 }