The only real option is to give up backward compatibility, to then throw out every broken language feature, and to then reimplement them properly. Unfortunately for those two languages, that would involve an awful lot of stuff getting thrown out and reimplemented, which is very likely why it hasn't happened yet.
Given how much core functionality needs to be reworked in both cases, I don't think they can really be saved. There are numerous other better languages out there, and it's easier just to use them instead of trying to salvage PHP or JavaScript.