https://raw.githubusercontent.com/pyllyukko/user.js/master/u...
user_pref("network.http.referer.userControlPolicy", x);
// TODO: https://github.com/pyllyukko/user.js/issues/94, commented-out XOriginPolicy/XOriginTrimmingPolicy = 2 prefs
user_pref("network.http.referer.spoofSource", x);
user_pref("network.http.referer.XOriginPolicy", x);