Implement getRange (returning an Iterable).

tools/dom/src/WrappedList.dart

Index: tools/dom/src/WrappedList.dart
diff --git a/tools/dom/src/WrappedList.dart b/tools/dom/src/WrappedList.dart
index b49e307cf069e381ea1c746a06f0cb6c2d4d76b5..8f6d1a79085ece997225a722ceb34495b6a85400 100644
--- a/tools/dom/src/WrappedList.dart
+++ b/tools/dom/src/WrappedList.dart
@@ -118,7 +118,7 @@ class _WrappedList<E> implements List<E> {
 
   List<E> sublist(int start, [int end]) => _list.sublist(start, end);
 
-  List<E> getRange(int start, int length) => sublist(start, start + length);
+  Iterable<E> getRange(int start, int end) => _list.getRange(start, end);
 
   void setRange(int start, int length, List<E> from, [int startFrom]) {
     _list.setRange(start, length, from, startFrom);