[gnome-shell] loginDialog: Return consistently from arrow function

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 42dabef8c7bd84c0fe4aac51084e99c24b3b7922
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue Feb 12 11:41:06 2019 +0100

    loginDialog: Return consistently from arrow function
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/606

 js/gdm/loginDialog.js | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/js/gdm/loginDialog.js b/js/gdm/loginDialog.js
index 3592b14df..fe6ca9aa6 100644
--- a/js/gdm/loginDialog.js
+++ b/js/gdm/loginDialog.js
@@ -1047,6 +1047,7 @@ var LoginDialog = GObject.registerClass({
                              return this._blockTimedLoginUntilIdle();
                          } else {
                              animationTime = delay;
+                             return null;
                          }
                      },