meta-window-actor-wayland.c: Fix a leak.

Turned up while running cinnamon --wayland thru valgrind.

Author: mtwebster

src/compositor/meta-window-actor-wayland.c

@@ -162,6 +162,8 @@ meta_window_actor_wayland_dispose (GObject *object)
         clutter_actor_remove_child (CLUTTER_ACTOR (window_actor), child_actor);
     }
 
+  g_list_free (children);
+
   G_OBJECT_CLASS (meta_window_actor_wayland_parent_class)->dispose (object);
 }