[gtk+] broadway: Handle NULL surface in update

[Alexander Larsson <alexl src gnome org>]

commit ec45d2f8c7cb02663109117548b0d489c7a22387
Author: Alexander Larsson <alexl redhat com>
Date:   Thu Dec 27 22:19:23 2012 +0100

    broadway: Handle NULL surface in update
    
    This happen if nothing has been drawn yet.

 gdk/broadway/gdkbroadway-server.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gdk/broadway/gdkbroadway-server.c b/gdk/broadway/gdkbroadway-server.c
index a2f9e00..803152a 100644
--- a/gdk/broadway/gdkbroadway-server.c
+++ b/gdk/broadway/gdkbroadway-server.c
@@ -598,6 +598,9 @@ _gdk_broadway_server_window_update (GdkBroadwayServer *server,
   BroadwayRequestUpdate msg;
   BroadwayShmSurfaceData *data;
 
+  if (surface == NULL)
+    return;
+
   data = cairo_surface_get_user_data (surface, &gdk_broadway_shm_cairo_key);
   g_assert (data != NULL);