[gnome-shell] panel: Relax check for existing signal handler

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

commit 16ca7a21a7c39406aa27dfa46357e9e5c4197e74
Author: Florian Müllner <fmuellner gnome org>
Date:   Sun Jun 30 01:04:32 2019 +0200

    panel: Relax check for existing signal handler
    
    Object.prototype.hasOwnProperty() is more precise than checking for
    falsiness, for instance the following is true:
    
      { foo: undefined }.hasOwnProperty('foo');
    
    However when checking for a handler ID, a more relaxed check is more
    appropriate, as particularly 0 is not a valid handler ID.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/626

 js/ui/panel.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/ui/panel.js b/js/ui/panel.js
index fcb51950f..6b8e60b19 100644
--- a/js/ui/panel.js
+++ b/js/ui/panel.js
@@ -1167,7 +1167,7 @@ class Panel extends St.Widget {
     }
 
     _onMenuSet(indicator) {
-        if (!indicator.menu || indicator.menu.hasOwnProperty('_openChangedId'))
+        if (!indicator.menu || indicator.menu._openChangedId)
             return;
 
         indicator.menu._openChangedId = indicator.menu.connect('open-state-changed',