anchor.diff:      }
     }
   
  -  Editor getCurrentEditor() {
  -    ws.File file = editorManager.currentFile;
  -    for (Editor editor in editorManager.editors) {
  -      if (editor.file == file) return editor;
  -    }
  -    return null;
  -  }
  +  Editor getCurrentEditor() => editorManager.currentEditor;
   
     // TODO(ussuri): The whole show...Message/Dialog() family: polymerize,
     // generalize and offload to SparkPolymerUI.
  
positive.code: 
    js.JsObject _designer;
    File _file;
  
    PolymerDesignerAction(Spark spark, SparkDialog dialog)
        : super(spark, "polymer-designer", "Edit in Polymer Designer…", dialog) {
      _designer = new js.JsObject.fromBrowserObject(
          _dialog.getElement('#polymerDesigner'));
      _dialog.getElement('#polymerDesignerClear').onClick.listen(_clearCode);
      _dialog.getElement('#polymerDesignerRevert').onClick.listen(_revertCode);
    }
  
    void _invoke([List<ws.Resource> resources]) {
      _file = spark._getFile(resources);
      _dialog.dialog.headerTitle = "Polymer Designer: ${_file.name}";
      _show();
      _file.getContents().then((String code) {
        _designer.callMethod('load', [code]);
      });
    }
  
    void _commit() {
      final js.JsObject promise = _designer.callMethod('getCode');
      promise.callMethod('then', [(String code) {
        _getCode(code);
        _cleanup();
      }]);
  
  
negative.code:     super._cancel();
    }
  
    void _revertDesign([_]) {
      _designer.callMethod('revertCode');
    }
  
    void _clearDesign([_]) {
      _designer.callMethod('setCode', ['']);
    }
  
    void _cleanup() {
  