[gtk+/gtk-3-12] a11y: Avoid a warning

[Matthias Clasen <matthiasc src gnome org>]

commit e8cccbb55c83dfb01ae768a44fc40b638d8d59a4
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 5 18:16:55 2014 -0400

    a11y: Avoid a warning
    
    The listbox row accessible code was giving warnings when
    parent is NULL, at destruction time.

 gtk/a11y/gtklistboxrowaccessible.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/a11y/gtklistboxrowaccessible.c b/gtk/a11y/gtklistboxrowaccessible.c
index 36e84a7..2fd548a 100644
--- a/gtk/a11y/gtklistboxrowaccessible.c
+++ b/gtk/a11y/gtklistboxrowaccessible.c
@@ -50,7 +50,8 @@ gtk_list_box_row_accessible_ref_state_set (AtkObject *obj)
   if (widget != NULL)
     {
       parent = gtk_widget_get_parent (widget);
-      if (gtk_list_box_get_selection_mode (GTK_LIST_BOX (parent)) != GTK_SELECTION_NONE)
+      if (parent != NULL && 
+          gtk_list_box_get_selection_mode (GTK_LIST_BOX (parent)) != GTK_SELECTION_NONE)
         atk_state_set_add_state (state_set, ATK_STATE_SELECTABLE);
 
       if (widget == (GtkWidget*)gtk_list_box_get_selected_row (GTK_LIST_BOX (parent)))