anchor.diff:    }
   
     @HostListener('click')
  +  @visibleForTemplate
     void handleClick() {
       _isKeyboardEvent = false;
       select();
     }
   
     @HostListener('keypress')
  +  @visibleForTemplate
     void handleKeyPress(KeyboardEvent event) {
       if (event.target != _root || !isSpaceKey(event)) return;
       // Required to prevent window from scrolling.
  
positive.code:   bool _checked = false;
  
    /// Current icon, depends on the state of [checked].
    Icon get icon => _checked ? checkedIcon : uncheckedIcon;
  
    /// Current tab index, depends on state of [disabled] and selection status
    /// if in group.
    @HostBinding('attr.tabindex')
    int get tabIndex => disabled ? -1 : _enabledTabIndex;
  
    int _enabledTabIndex = 0;
  
negative.code: 
    // Capture keydown to forward event to radio group when cycling focus.
    @HostListener('keydown')
    @visibleForTemplate
    void handleKeyDown(KeyboardEvent event) {
      if (event.target != _root) return;
      var focusEvent = FocusMoveEvent.fromKeyboardEvent(this, event);
  