So #jShelter seems to break with #TorBrowser's way of removing potentially harmful #javascript, prefering what seems a more random and experimental method, #Farbling that says it produces inconsistent behaviours. Is that not worse than a broken page that Tor produces occasionally?

Is there an addon that seeks to imitate TorBrowser's method of providing a safer js?

It will likely be beneficial for those who don't use TorBrowser but still want safer javascript.