[gnome-shell] ctrlAltTab: Use arrow function for callback

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

commit 69f63dc94ff0571137c4bb0756f24a2e32027bfa
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Nov 11 15:01:00 2019 +0100

    ctrlAltTab: Use arrow function for callback
    
    This was left over because we are binding a different `this`, but
    it is easy enough to replace.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/805

 js/ui/ctrlAltTab.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/js/ui/ctrlAltTab.js b/js/ui/ctrlAltTab.js
index cb7e4cd691..4104f49f97 100644
--- a/js/ui/ctrlAltTab.js
+++ b/js/ui/ctrlAltTab.js
@@ -100,9 +100,9 @@ var CtrlAltTabManager = class CtrlAltTabManager {
 
                 items.push({ name: windows[i].title,
                              proxy: windows[i].get_compositor_private(),
-                             focusCallback: function(timestamp) {
-                                 Main.activateWindow(this, timestamp);
-                             }.bind(windows[i]),
+                             focusCallback: timestamp => {
+                                 Main.activateWindow(windows[i], timestamp);
+                             },
                              iconActor: icon,
                              iconName: iconName,
                              sortGroup: SortGroup.MIDDLE });