refactor(aria/listbox): Add accessors for pattern properties

Author: adolgachev

src/aria/listbox/listbox.ts

@@ -51,7 +51,7 @@ import {ComboboxPopup} from '../combobox';
     '[attr.aria-disabled]': '_pattern.disabled()',
     '[attr.aria-orientation]': '_pattern.orientation()',
     '[attr.aria-multiselectable]': '_pattern.multi()',
-    '[attr.aria-activedescendant]': '_pattern.activedescendant()',
+    '[attr.aria-activedescendant]': 'activedescendant()',
     '(keydown)': '_pattern.onKeydown($event)',
     '(pointerdown)': '_pattern.onPointerdown($event)',
     '(focusin)': 'onFocus()',
@@ -118,6 +118,12 @@ export class Listbox<V> {
   /** The values of the current selected items. */
   value = model<V[]>([]);
 
+  /** The id of the current active item. */
+  readonly activedescendant = computed(() => this._pattern.activedescendant());
+
+  /** Whether selection should follow focus. */
+  readonly followFocus = computed(() => this._pattern.followFocus());
+
   /** The Listbox UIPattern. */
   readonly _pattern: ListboxPattern<V>;