It has never shipped after being implemented years ago,
and was removed from spec in September 2022:
https://github.com/w3c/webappsec-csp/pull/564
Now skipping navigate-to WPT tests. Filed issue upstream for their future removal:
https://github.com/w3c/webappsec-csp/issues/608
Consensus seems to agree to remove, will do in follow up bug once landed.
Also removed our own tests.
Added a hack in StartDocumentLoad as just removing the navigate-to check call
breaks some inhertiance, see comment for more info.
Differential Revision: https://phabricator.services.mozilla.com/D181630