Roll 50: Updated for push to origin/master.

tools/dom/src/dartium_CssClassSet.dart

 // Copyright (c) 2015, 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 html;
 
 /**
  * A set (union) of the CSS classes that are present in a set of elements.
  * Implemented separately from _ElementCssClassSet for performance.
  */
@@ skipping 55 matching lines @@
 }
 
 class _ElementCssClassSet extends CssClassSetImpl {
   final Element _element;
 
   _ElementCssClassSet(this._element);
 
   Set<String> readClasses() {
     var s = new LinkedHashSet<String>();
     var classname = _element.className;
+    if (classname is svg.AnimatedString) {
+      classname = classname.baseVal;
+    }
 
     for (String name in classname.split(' ')) {
       String trimmed = name.trim();
       if (!trimmed.isEmpty) {
         s.add(trimmed);
       }
     }
     return s;
   }
 
   void writeClasses(Set<String> s) {
     _element.className = s.join(' ');
   }
 }