Fix various warnings and errors in html_diff and its annotations.

client/html/src/ElementWrappingImplementation.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.
 
 // TODO(jacobr): use Lists.dart to remove some of the duplicated functionality.
 class _ChildrenElementList implements ElementList {
   // Raw Element.
   final _element;
   final _childElements;
 
@@ skipping 556 matching lines @@
   }
 
   void set elements(Collection<Element> value) {
     final elements = this.elements;
     elements.clear();
     elements.addAll(value);
   }
 
   /**
    * @domName childElementCount, firstElementChild, lastElementChild,
-   *   children, appendChild
+   *   children, Node.appendChild
    */
   ElementList get elements() {
     if (_elements == null) {
       _elements = new _ChildrenElementList._wrap(_ptr);
     }
     return _elements;
   }
 
   /** @domName className, classList */
   Set<String> get classes() {
@@ skipping 173 matching lines @@
 
   ElementEvents get on() {
     if (_on === null) {
       _on = new ElementEventsImplementation._wrap(_ptr);
     }
     return _on;
   }
 
   Element clone(bool deep) => super.clone(deep);
 }