[metacity] xrender: avoid calling add_damage with None region

[Alberts Muktupāvels <muktupavels src gnome org>]

commit f82f65b1fc08ca9f880f6e2359ad1f6fb12e44dd
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Sep 8 00:44:19 2019 +0300

    xrender: avoid calling add_damage with None region
    
    Otherwise we will crash with BadRegion error.

 src/compositor/meta-compositor-xrender.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
---
diff --git a/src/compositor/meta-compositor-xrender.c b/src/compositor/meta-compositor-xrender.c
index ed31da71..50f78c02 100644
--- a/src/compositor/meta-compositor-xrender.c
+++ b/src/compositor/meta-compositor-xrender.c
@@ -2049,10 +2049,8 @@ notify_decorated_cb (MetaWindow            *window,
                      MetaCompositorXRender *xrender)
 {
   MetaCompWindow *cw;
-  XserverRegion damage;
 
   cw = find_comp_window_by_window (xrender, window);
-  damage = None;
 
   if (cw == NULL)
     return;
@@ -2121,7 +2119,8 @@ notify_decorated_cb (MetaWindow            *window,
 
   if (cw->extents != None)
     {
-      damage = cw->extents;
+      dump_xserver_region (xrender, "notify_decorated_cb", cw->extents);
+      add_damage (xrender, cw->extents);
       cw->extents = None;
     }
 
@@ -2164,8 +2163,6 @@ notify_decorated_cb (MetaWindow            *window,
 
   meta_error_trap_pop (window->display);
 
-  dump_xserver_region (xrender, "notify_decorated_cb", damage);
-  add_damage (xrender, damage);
   cw->damaged = TRUE;
 
   xrender->clip_changed = TRUE;