[gnome-shell] magnifier: Add missing import

[Florian Müllner <fmuellner src gnome org>]

commit ba97e8da7ac0a9d9c332882aa77a7b697816b15d
Author: Florian Müllner <fmuellner gnome org>
Date:   Thu Jan 31 14:05:44 2019 +0100

    magnifier: Add missing import
    
    This was missing from commit a7bb8ee6398.

 js/ui/magnifier.js | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/js/ui/magnifier.js b/js/ui/magnifier.js
index 661146a1a..0b480f117 100644
--- a/js/ui/magnifier.js
+++ b/js/ui/magnifier.js
@@ -2,6 +2,7 @@
 
 const Atspi = imports.gi.Atspi;
 const Clutter = imports.gi.Clutter;
+const Cogl = imports.gi.Cogl;
 const GDesktopEnums = imports.gi.GDesktopEnums;
 const Gio = imports.gi.Gio;
 const GLib = imports.gi.GLib;