Search for Pale Moon. It uses the Mozilla source code, but states that it is in NO way affiliated with Mozilla. The add-ons work too (along with greasemonkey, if you ise that here).
While this Pale Moon browser seems technically competent, I wouldn't go thinking that the M.C. Straver fellow is a Christian, right wing, conservative, supporter of the second amendment. It appears the guy is very talented, but has some strange ideas about art.