Implement getRange (returning an Iterable).

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 $LIBRARYNAME;
 
 // TODO(jacobr): use _Lists.dart to remove some of the duplicated
 // functionality.
 class _ChildrenElementList extends ListBase<Element> {
   // Raw Element.
@@ skipping 187 matching lines @@
   }
 
   void removeRange(int start, int rangeLength) {
     throw new UnimplementedError();
   }
 
   void insertRange(int start, int rangeLength, [initialValue = null]) {
     throw new UnimplementedError();
   }
 
+  Iterable getRange(int start, int end)  {
+    throw new UnimplementedError();
+  }
+
   List sublist(int start, [int end]) {
     if (end == null) end = length;
     return new _FrozenElementList._wrap(Lists.getRange(this, start, end, []));
   }
 
-  List getRange(int start, int rangeLength) =>
-      sublist(start, start + rangeLength);
-
   int indexOf(Element element, [int start = 0]) {
     return Lists.indexOf(this, element, start, this.length);
   }
 
   int lastIndexOf(Element element, [int start = null]) {
     if (start == null) start = length - 1;
     return Lists.lastIndexOf(this, element, start);
   }
 
   void insert(int index, Element element) {
@@ skipping 767 matching lines @@
   const ScrollAlignment._internal(this._value);
   toString() => 'ScrollAlignment.$_value';
 
   /// Attempt to align the element to the top of the scrollable area.
   static const TOP = const ScrollAlignment._internal('TOP');
   /// Attempt to center the element in the scrollable area.
   static const CENTER = const ScrollAlignment._internal('CENTER');
   /// Attempt to align the element to the bottom of the scrollable area.
   static const BOTTOM = const ScrollAlignment._internal('BOTTOM');
 }