Restore visibility of windows in initial-setup mode

gnome-initial-setup runs a regular X window, so we need to show it.

https://bugzilla.gnome.org/show_bug.cgi?id=696235

js/ui/sessionMode.js

@@ -79,6 +79,7 @@ const _modes = {
     },
 
     'initial-setup': {
+        hasWindows: true,
         isPrimary: true,
         components: ['keyring'],
         panel: {