chore(combos): revert wrongly picked changes

Author: wnvko

projects/igniteui-angular/src/lib/combo/combo.common.ts

@@ -879,8 +879,6 @@ export abstract class IgxComboBaseDirective extends DisplayDensityBase implement
     public filteringOptions: IComboFilteringOptions = {
         caseSensitive: false
     };
-    /** @hidden @internal */
-    public activeDescendant = '';
 
     protected _data = [];
     protected _value = '';

projects/igniteui-angular/src/lib/combo/combo.component.html

@@ -49,9 +49,8 @@
     </ng-container>
     <div #dropdownItemContainer class="igx-combo__content" [style.overflow]="'hidden'"
         [style.maxHeight.px]="itemsMaxHeight" [igxDropDownItemNavigation]="dropdown" (focus)="dropdown.onFocus()"
-        [tabindex]="dropdown.collapsed ? -1 : 0" [attr.id]="dropdown.id" aria-multiselectable="true"
-        [attr.aria-activedescendant]="this.activeDescendant">
-        <igx-combo-item [itemHeight]='itemHeight' *igxFor="let item of data
+        [tabindex]="dropdown.collapsed ? -1 : 0" role="listbox" [attr.id]="dropdown.id">
+        <igx-combo-item role="option" [itemHeight]='itemHeight' *igxFor="let item of data
             | comboFiltering:filterFunction:filterValue:filteringOptions:filterable:displayKey
             | comboGrouping:groupKey:valueKey:groupSortingDirection;
             index as rowIndex; containerSize: itemsMaxHeight; scrollOrientation: 'vertical'; itemSize: itemHeight"