[gtk] stack: protect set_visible_child_name from NULL stack

[Marco Trevisan <marcotrevi src gnome org>]

commit c15b64b7206e6c6d129b5d732878bc61221390d5
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed Apr 18 20:58:57 2018 -0500

    stack: protect set_visible_child_name from NULL stack
    
    Return with error if gtk_stack_set_visible_child_name is called
    with NULL parameter
    
    
    (cherry picked from commit 2ee5aee4a9f01cce3dda7dff877070b62c3e2880)

 gtk/gtkstack.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index b508aee659..34f5491c48 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -1670,6 +1670,8 @@ gtk_stack_set_visible_child_name (GtkStack   *stack,
 {
   GtkStackPrivate *priv = gtk_stack_get_instance_private (stack);
 
+  g_return_if_fail (GTK_IS_STACK (stack));
+
   gtk_stack_set_visible_child_full (stack, name, priv->transition_type);
 }