baseAppView: Destroy icon when removing

We cannot rely on the garbage collector to do that in a timely
manner, so destroy it explicitly.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/841

js/ui/appDisplay.js

@@ -173,10 +173,11 @@ class BaseAppView {
         // Remove old app icons
         removedApps.forEach(icon => {
             let iconIndex = this._allItems.indexOf(icon);
+            let id = icon.id;
 
             this._allItems.splice(iconIndex, 1);
-            this._grid.removeItem(icon);
-            delete this._items[icon.id];
+            icon.destroy();
+            delete this._items[id];
         });
 
         // Add new app icons