Git commits in Moodle 2.8.9 by Jetha Chan

commit 596e4603aec8f2253eb247279357c1e4e18a69d8
Author: Jetha Chan <jetha@moodle.com>
Date:   Thu, 02 Jul 2015 10:19:50 +0800
Tag:    v2.8.9

MDL-50685 core_form: disable hidden options, don't just hide