Always chain up in ::style-updated

This was not handled consistently, but the default handler
does useful things, so we should always chain up.

gtk/gtktreeview.c

@@ -8489,6 +8489,8 @@ gtk_tree_view_style_updated (GtkWidget *widget)
   GList *list;
   GtkTreeViewColumn *column;
 
+  GTK_WIDGET_CLASS (gtk_tree_view_parent_class)->style_updated (widget);
+
   if (gtk_widget_get_realized (widget))
     {
       GtkStyleContext *context;