It does use an extensive HSTS preload list. So if you go to for example http://Bugzilla.mozilla.org http://Bugzilla.mozilla.org it will actually never hit http

It does use an extensive HSTS preload list. So if you go to for example http://Bugzilla.mozilla.org http://Bugzilla.mozilla.org it will actually never hit http and go straight to https. Same list as in Firefox and Chrome. (iOS feature, all apps get this for free)