notificationDaemon: Close calendar when opening app

Just like we leave the overview when activating a notification,
the calendar popup should be closed - after all, the only case
where the calendar is open when a notification's default action
is activated is the user clicking an entry in the message list's
notification section.

https://bugzilla.gnome.org/show_bug.cgi?id=744817

js/ui/notificationDaemon.js

@@ -561,6 +561,7 @@ const FdoNotificationDaemonSource = new Lang.Class({
 
         this.app.activate();
         Main.overview.hide();
+        Main.panel.closeCalendar();
     },
 
     destroy: function() {