MFH: r501856

www/firefox: restore SafeBrowsing v4 after r495403

Required for phishing protection. Not covered by uBlock Origin lists.
Looks like #Mozilla didn't announce the POLA-violating change anywhere
public despite backporting to ESR60.

https://bugzilla.mozilla.org/show_bug.cgi?id=1531176

Approved by: ports-secteam blanket