authPrompt: Initialize property in _init()

This avoid a "reference to undefined property" warning when using
it in a comparison.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/1035

diff --git a/js/gdm/authPrompt.js b/js/gdm/authPrompt.js
index 8cb1f305c98dae941e987e4f47aca9df92558502..0cb2462a0ce6f821665671aef8b13b4b278afe12 100644 (file)
--- a/js/gdm/authPrompt.js
+++ b/js/gdm/authPrompt.js
@@ -55,6 +55,7 @@ var AuthPrompt = GObject.registerClass({
 
         this._gdmClient = gdmClient;
         this._mode = mode;
+        this._defaultButtonWellActor = null;
 
         let reauthenticationOnly;
         if (this._mode == AuthPromptMode.UNLOCK_ONLY)