anchor.diff:      //from blowing up. I'm not sure that's reasoable.
       if (this.selectedProperty != null && this.selectedProperty.isNotEmpty) {
         //Note: Reflection is required to work properly with checkboxes
  -      reflect(item).setField(new Symbol('${this.selectedProperty}'), isSelected);
  +      try {
  +          // polymer-ui-submenu-item works only with this
  +          reflect(item).setField(new Symbol('${this.selectedProperty}'), isSelected);
  +      } catch(e) { // required for polymer_ui_breadcrumbs (when an attribute is set on a DOM element
  +          if(isSelected) {
  +            item.attributes[this.selectedProperty] = isSelected.toString();
  +          } else {
  +            item.attributes.remove(this.selectedProperty);
  +          }
  +       }
       }
     }
     
  
positive.code:   MutationObserver _observer;
    
    Stream<CustomEvent> get onPolymerSelect {
      PolymerSelection selection = $['selection'] as PolymerSelection;
      if(selection != null) {
        // TODO return selection.onPolymerSelect;
      }
  
negative.code:       }
        target = target.parentNode;
      }
      return -1;
    }
  }
  