This applies for refreshes resulting from either a `<meta>` refresh or the Refresh header. Referrer Policy is honored. Because exposing the referrer in a new place could have privacy implications, this behavior is gated behind a disabled pref until anti-tracking has been considered in bug 1928294. Some WPTs that D227450 touches are cleaned up a bit. Differential Revision: https://phabricator.services.mozilla.com/D227450