switcherPopup: Always return true when the popup finished early

When the switcherPopup was initiated successfully, we return true,
otherwise the WindowManager will try to destroy it. Since an early
release of the keystroke will also switch to another application and
close the switcher just fine, we should return true to indicate success
here.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/167

js/ui/switcherPopup.js

@@ -130,7 +130,7 @@ var SwitcherPopup = GObject.registerClass({
             let [x_, y_, mods] = global.get_pointer();
             if (!(mods & this._modifierMask)) {
                 this._finish(global.get_current_time());
-                return false;
+                return true;
             }
         } else {
             this._resetNoModsTimeout();