[gnome-shell] overview: Fix XDnD

[Jasper St. Pierre <jstpierre src gnome org>]

commit c1993a6ffc5a3c502dfc604652ee79acd7c47e2d
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Mon Apr 22 17:56:34 2013 -0400

    overview: Fix XDnD
    
    I accidentally removed this import which some XDnD code depends upon.

 js/ui/overview.js | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/js/ui/overview.js b/js/ui/overview.js
index ee2c076..fb6b910 100644
--- a/js/ui/overview.js
+++ b/js/ui/overview.js
@@ -19,6 +19,7 @@ const OverviewControls = imports.ui.overviewControls;
 const Panel = imports.ui.panel;
 const Params = imports.misc.params;
 const Tweener = imports.ui.tweener;
+const WorkspaceThumbnail = imports.ui.workspaceThumbnail;
 
 // Time for initial animation going into Overview mode
 const ANIMATION_TIME = 0.25;