[gtk] window: Return no item for no item name

[Benjamin Otte <otte src gnome org>]

commit 78d013f8d3d8c91b32413f1b36fbb5f19a325696
Author: Benjamin Otte <otte redhat com>
Date:   Wed Feb 27 07:29:57 2019 +0100

    window: Return no item for no item name

 gtk/gtkwindow.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index ae36f5f092..600e96e515 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -4620,6 +4620,8 @@ gtk_window_get_icon_for_size (GtkWindow *window,
 
   if (!name)
     name = default_icon_name;
+  if (!name)
+    return NULL;
 
   info = gtk_icon_theme_lookup_icon (gtk_icon_theme_get_default (),
                                      name, size,