Fix bug in html element remove.

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

 // Copyright (c) 2012, 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;
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
 class _ChildrenElementList implements List {
   // Raw Element.
@@ skipping 135 matching lines @@
     return IterableMixinWorkaround.reduce(this, initialValue, combine);
   }
 
   void setRange(int start, int rangeLength, List from, [int startFrom = 0]) {
     throw new UnimplementedError();
   }
 
   void remove(Object object) {
     if (object is Element) {
       Element element = object;
-      if (identical(element.parentNode, this)) {
+      if (identical(element.parentNode, _element)) {
         _element.$dom_removeChild(element);
       }
     }
   }
 
   void removeAll(Iterable elements) {
     IterableMixinWorkaround.removeAll(this, elements);
   }
 
   void retainAll(Iterable elements) {
@@ skipping 871 matching lines @@
 $if DART2JS
   // Optimization to improve performance until the dart2js compiler inlines this
   // method.
   static dynamic createElement_tag(String tag) =>
       JS('Element', 'document.createElement(#)', tag);
 $else
   static Element createElement_tag(String tag) =>
       document.$dom_createElement(tag);
 $endif
 }