Redo TLA support by taking it from bellard/quickjs

[saghul]

Turns out ours is a bit crude. JS_EvalFunction won't return a promise in all cases, for example.

More importantly, it would bring the forks closer toghether.

Relevant commits:

bellard/quickjs@6e4931c
bellard/quickjs@00967aa
bellard/quickjs@67723c9
bellard/quickjs@8405876
bellard/quickjs@e44b793