workspace: Add missing chain-up for finalize()

https://bugzilla.gnome.org/show_bug.cgi?id=708070

src/core/workspace.c

@@ -78,6 +78,7 @@ static void
 meta_workspace_finalize (GObject *object)
 {
   /* Actual freeing done in meta_workspace_remove() for now */
+  G_OBJECT_CLASS (meta_workspace_parent_class)->finalize (object);
 }
 
 static void