[gnome-shell] st-private: Warn if creating shadow for unallocated actors

[Jonas Ådahl <jadahl src gnome org>]

commit e39d7152f2e2b5bc16fcf82b6bc8f06a31d5fecb
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Thu Apr 12 21:25:21 2018 -0400

    st-private: Warn if creating shadow for unallocated actors

 src/st/st-private.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/src/st/st-private.c b/src/st/st-private.c
index 882c2631e..512fbba45 100644
--- a/src/st/st-private.c
+++ b/src/st/st-private.c
@@ -432,6 +432,8 @@ _st_create_shadow_pipeline_from_actor (StShadow     *shadow_spec,
   CoglPipeline *shadow_pipeline = NULL;
   float width, height;
 
+  g_return_val_if_fail (clutter_actor_has_allocation (actor), NULL);
+
   clutter_actor_get_size (actor, &width, &height);
 
   if (width == 0 || height == 0)