[gnome-shell] Fix possible property access on undefined object

[Dan Winship <danw src gnome org>]

commit 4aa80105ca4469ddbcf9537eee47a067e184bc7d
Author: Giovanni Campagna <scampa giovanni gmail com>
Date:   Mon Jul 19 23:27:56 2010 +0200

    Fix possible property access on undefined object
    
    PopupMenuManager allows the insertion of menu without a sourceActor
    (or with a null one), but never checks before calling contains() on
    it.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=622730

 js/ui/popupMenu.js |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/popupMenu.js b/js/ui/popupMenu.js
index 8ac9ef6..2826edd 100644
--- a/js/ui/popupMenu.js
+++ b/js/ui/popupMenu.js
@@ -499,13 +499,14 @@ PopupMenuManager.prototype = {
         let src = event.get_source();
         return this._activeMenu != null
                 && (this._activeMenu.actor.contains(src) ||
-                    this._activeMenu.sourceActor.contains(src));
+                    (this._activeMenu.sourceActor && this._activeMenu.sourceActor.contains(src)));
     },
 
     _eventIsOnAnyMenuSource: function(event) {
         let src = event.get_source();
         for (let i = 0; i < this._menus.length; i++) {
-            if (this._menus[i].sourceActor.contains(src))
+            let menu = this._menus[i];
+            if (menu.sourceActor && menu.sourceActor.contains(src))
                 return true;
         }
         return false;