Editorial: ProxyTarget is always a function object in GetFunctionRealm

[kimjg1119]

In GetFunctionRealm, step 3.c. call GetFunctionRealm recursively with proxyTarget which assumes that proxyTarget is a function object.

If my investigation is correct, proxy exotic objects are generated in ProxyCreate and it is callable only if the target is callable. Thus if a function object has a target, then it is also a function object thus it isn't a spec bug. However I think add an assertion here will be helpful.

[michaelficarra]

This is great!

[kimjg1119]

Can we also remove step 3.a? It seems that ValidateNonRevokedProxy only checks ProxyTarget, but it seems that it is always Object when obj is callable.

[michaelficarra]

@kimjg1119 All proxies of callable objects (including revocable proxies) are themselves callable. When a callable revocable proxy is revoked, it remains callable. So ValidateNonRevokedProxy is needed to check that the proxy has not yet been revoked (and that [[ProxyTarget]] is a function object rather than null).