anchor.diff:    /// These CSS classes will be copied into the popup overlay. The classes can
     /// be used to select DOM elements within the overlay when the popup is open.
     @Input()
  -  String popupClass;
  +  set popupClass(String value) {
  +    _popupClass = constructEncapsulatedCss(value, element.classes);
  +  }
  +
  +  String get popupClass => _popupClass;
  +  String _popupClass;
  +
  +  MenuPopupComponent(this.element);
   
     @ViewChild(MenuItemGroupsComponent)
     set menuItemGroups(MenuItemGroupsComponent groups) {
  
positive.code: import 'package:angular_components/material_popup/material_popup.dart';
  import 'package:angular_components/mixins/focusable_mixin.dart';
  import 'package:angular_components/model/menu/menu.dart';
  
  /// A popup that renders a [MenuModel] using a [MenuItemGroupsComponent].
  @Component(
  
negative.code:     styleUrls: ['menu_popup.scss.css'],
      changeDetection: ChangeDetectionStrategy.OnPush)
  class MenuPopupComponent extends Object with FocusableMixin, MenuPopupWrapper {
    HtmlElement element;
  
    @Input()
    PopupSource popupSource;
  
  