switcherPopup: Hide the top level actor on _init

destroy() checks if we are visible to decide whether to destroy the
actor immediately or after a fade out animation. Since actors are
visible by default it would always end up destroying only after the
animation time.

https://bugzilla.gnome.org/show_bug.cgi?id=691963

js/ui/switcherPopup.js

@@ -46,7 +46,8 @@ const SwitcherPopup = new Lang.Class({
         this._selectedIndex = 0;
 
         this.actor = new Shell.GenericContainer({ style_class: 'switcher-popup',
-                                                  reactive: true });
+                                                  reactive: true,
+                                                  visible: false });
         this.actor.connect('get-preferred-width', Lang.bind(this, this._getPreferredWidth));
         this.actor.connect('get-preferred-height', Lang.bind(this, this._getPreferredHeight));
         this.actor.connect('allocate', Lang.bind(this, this._allocate));