Git commits in Moodle 3.9.0 by Sam Hemelryk

commit 841d855993cbaaf9c2d5b8fa381026c2d3979cc8
Author: Sam Hemelryk <sam.hemelryk@totaralearning.com>
Date:   Tue, 15 Oct 2019 12:28:25 +0800
Tag:    v3.9.0-beta

MDL-67175 mod_scorm: sync XHR requests use sendBeacon when available