anchor.diff:        return;
       }
       queryParams.channel = channel;
  +    final buttonText =
  +        _channelsDropdownButton.querySelector('.mdc-button__label')!;
  +    buttonText.text = '$channel channel';
       dartServices.rootUrl = Channel.urlMapping[channel]!;
       updateVersions();
       performAnalysis();
  
positive.code:         .listen((_) => showPackageVersionsDialog());
  
      _initChannelsMenu();
      final channelsButton = _channelsDropdownButton;
      if (channelsButton is ButtonElement) {
        MDCButton(channelsButton)
            .onClick
            .listen((e) => _toggleMenu(_channelsMenu));
      }
    }
  
    MDCMenu _initSamplesMenu() {
  
negative.code: 
    MDCMenu get _samplesMenu => _initSamplesMenu();
  
    ButtonElement get _channelsDropdownButton =>
        querySelector('#channels-dropdown-button') as ButtonElement;
  
    bool get _isCompletionActive => editor.completionActive;
  
  