[gnome-shell/wip/carlosg/issue-539] windowManager: listen actively to windows being destroyed during WS switch

[Carlos Garnacho <carlosg src gnome org>]

commit 226372bd14a3c2a371d038ef57e46ac7aa7ba9d1
Author: Carlos Garnacho <carlosg gnome org>
Date:   Thu Sep 6 21:50:21 2018 +0200

    windowManager: listen actively to windows being destroyed during WS switch
    
    Prevents gjs from dealing with already dispose()d objects.
    
    Closes: https://gitlab.gnome.org/GNOME/gnome-shell/issues/539

 js/ui/windowManager.js | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/windowManager.js b/js/ui/windowManager.js
index b6627e253..2295e3010 100644
--- a/js/ui/windowManager.js
+++ b/js/ui/windowManager.js
@@ -1910,6 +1910,14 @@ var WindowManager = new Lang.Class({
                 actor.visible = visible;
             }
         }
+
+        for (let i = 0; i < switchData.windows.length; i++) {
+            let w = switchData.windows[i];
+
+            w.windowDestroyId = w.window.connect('destroy', () => {
+                switchData.windows.splice(switchData.windows.indexOf(w), 1);
+            });
+        }
     },
 
     _finishWorkspaceSwitch(switchData) {
@@ -1917,9 +1925,8 @@ var WindowManager = new Lang.Class({
 
         for (let i = 0; i < switchData.windows.length; i++) {
             let w = switchData.windows[i];
-            if (w.window.is_destroyed()) // Window gone
-                continue;
 
+            w.window.disconnect(w.windowDestroyId);
             w.window.reparent(w.parent);
 
             if (w.window.get_meta_window().get_workspace() !=