[mutter/wayland] window-group: Fix compiler warning

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

commit 9682a2aea42d52e37487e28d3ae04f88320ae5fb
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Fri Aug 23 22:11:37 2013 -0400

    window-group: Fix compiler warning

 src/compositor/meta-window-group.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/compositor/meta-window-group.c b/src/compositor/meta-window-group.c
index 8fddc5e..fe65f39 100644
--- a/src/compositor/meta-window-group.c
+++ b/src/compositor/meta-window-group.c
@@ -187,7 +187,7 @@ meta_window_group_paint (ClutterActor *actor)
       if (META_IS_WINDOW_ACTOR (child))
         {
           MetaWindow *meta_window;
-          MetaWindowActor *window_actor = child;
+          MetaWindowActor *window_actor = META_WINDOW_ACTOR (child);
           int x, y;
 
           if (!meta_actor_is_untransformed (CLUTTER_ACTOR (window_actor), &x, &y))