[gnome-shell] appDisplay: don't try to close the popup menu that is already destroyed

[Marco Trevisan <marcotrevi src gnome org>]

commit 35eac697c10f6f3271f2d30d61df0e438ff0aaa6
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed Dec 6 00:55:37 2017 -0500

    appDisplay: don't try to close the popup menu that is already destroyed
    
    This would lead to a JS error otherwise, as we might end up
    in deleting actors that have been already destructed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=791233

 js/ui/appDisplay.js |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index 9b92311..c309471 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -1872,11 +1872,14 @@ var AppIconMenu = new Lang.Class({
         this.actor.add_style_class_name('app-well-menu');
 
         // Chain our visibility and lifecycle to that of the source
-        source.actor.connect('notify::mapped', Lang.bind(this, function () {
+        this._sourceMappedId = source.actor.connect('notify::mapped', () => {
             if (!source.actor.mapped)
                 this.close();
-        }));
-        source.actor.connect('destroy', Lang.bind(this, this.destroy));
+        });
+        source.actor.connect('destroy', () => {
+            source.actor.disconnect(this._sourceMappedId);
+            this.destroy();
+        });
 
         Main.uiGroup.add_actor(this.actor);
     },