Fixing DataTransferItemList List<> behavior

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

Index: tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_WebKitCSSKeyframesRule.darttemplate b/tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
similarity index 55%
copy from tools/dom/templates/html/impl/impl_WebKitCSSKeyframesRule.darttemplate
copy to tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
index a0c7f902fbc4b2654325781a89f85910067bec31..b43806f52ce0eaddf501945b4a6a9bcd158d6dea 100644
--- a/tools/dom/templates/html/impl/impl_WebKitCSSKeyframesRule.darttemplate
+++ b/tools/dom/templates/html/impl/impl_DataTransferItemList.darttemplate
@@ -1,4 +1,4 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2013, 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.
 
@@ -8,13 +8,12 @@ part of $LIBRARYNAME;
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$MIXINS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
 
+  DataTransferItem operator[] (int index) {
 $if DART2JS
-  void appendRule(String rule) {
-    if (JS('bool', '("appendRule" in #)', this)) {
-      JS('', '#.appendRule(#)', this, rule);
-    } else {
-      JS('', '#.insertRule(#)', this, rule);
-    }
-  }
+    return JS('DataTransferItem', '#[#]', this, index);
+$else
+    return __getter__(index);
 $endif
+  }
+
 }