anchor.diff:    /// DOM for the optionGroup.
     final Function trackByIndexFn = indexIdentityFn;
   
  -  bool _disabled = false;
     bool _listAutoFocus = false;
     int _autoFocusIndex;
   
  
positive.code: import 'package:angular_components/model/ui/has_factory.dart';
  import 'package:angular_components/model/ui/has_renderer.dart';
  import 'package:angular_components/model/ui/template_support.dart';
  import 'package:angular_components/utils/angular/properties/properties.dart';
  
  import 'material_select_base.dart';
  import 'material_select_item.dart';
  
negative.code:   ///
    /// Defaults to false.
    @Input()
    bool disabled = false;
  
    @HostBinding('attr.aria-disabled')
    String get disabledStr => '$disabled';
  
    @override
    ItemRenderer<T> get itemRenderer => _itemRenderer;
  