anchor.diff:          .listen((e) => _toggleMenu(_channelsMenu));
     }
   
  -  MDCMenu _initSamplesMenu() {
  +  MDCMenu _buildSamplesMenu() {
       final element = querySelector('#samples-menu')!;
       element.children.clear();
   
  -    final samples = [
  +    const samples = [
         Sample('e75b493dae1287757c5e1d77a0dc73f1', 'Counter', Layout.flutter),
         Sample('5c0e154dd50af4a9ac856908061291bc', 'Sunflower', Layout.flutter),
         Sample('a1d5666d6b54a45eb170b897895cf757', 'Draggables & physics',
  
positive.code:     _tabExpandController = null;
    }
  
    MaterialTabController _initTabs() {
      final webLayoutTabController =
          MaterialTabController(MDCTabBar(_webTabBar.element));
      for (final name in ['dart', 'html', 'css']) {
  
negative.code: 
    ButtonElement get _samplesDropdownButton =>
        querySelector('#samples-dropdown-button') as ButtonElement;
  
    ButtonElement get _channelsDropdownButton =>
        querySelector('#channels-dropdown-button') as ButtonElement;
  