[mutter/wayland] compositor: Don't call process_damage if the window is gone

[Adel Gadllah <agadllah src gnome org>]

commit 6eeaf09ab70a001d30d3f72599963d7448ca5f40
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Thu Mar 27 13:57:53 2014 +0100

    compositor: Don't call process_damage if the window is gone
    
    We might get a damage event for an already unmanaged window calling
    process_damage is pointless and causes a crash so simply skip that case.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=727115

 src/compositor/compositor.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/compositor/compositor.c b/src/compositor/compositor.c
index 22eec9e..54fcd44 100644
--- a/src/compositor/compositor.c
+++ b/src/compositor/compositor.c
@@ -930,7 +930,8 @@ meta_compositor_process_event (MetaCompositor *compositor,
           window = meta_display_lookup_x_window (compositor->display, xwin);
         }
 
-      process_damage (compositor, (XDamageNotifyEvent *) event, window);
+      if (window)
+        process_damage (compositor, (XDamageNotifyEvent *) event, window);
     }
 
   /* Clutter needs to know about MapNotify events otherwise it will