anchor.diff:        if (i >= 0) {
           var item = this.items[i];
           var s = this._valueForNode(item);
  -        if(s == null){
  +        if (s == null) {
             s = i;
           }
           if (this.multi) {
  
positive.code:    * Specifies the CSS class to be used to add to the selected element.
     */
    @published
    String selectedClass= 'polymer-selected';
  
    /**
     * Specifies the property to be used to set on the selected element
  
negative.code:       nodes = (this.$['items'] as dom.ContentElement).getDistributedNodes();
      }
  
      return nodes.where((dom.Element e) {
        return e != null && e.localName != 'template';
      }).toList();
    }
  