util: remove dead code from inspect()

[Trott]

It is not possible for a ECMAScript class to have a prototype that isn't
either a function or null. Test coverage statistics seem to bear out
that the code removed here is unreachable.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines

[Trott]

It is not possible for a ECMAScript class to have a prototype that isn't
either a function or null.

@ljharb @BridgeAR If I'm wrong and there's some clever way to monkeypatch things to make this code reachable, I'd love to be corrected.

[BridgeAR]

It's possible to reach the code by setting a new prototype:

class A {}
Object.setPrototypeOf(A, Map.prototype)

[Trott]

It's possible to reach the code by setting a new prototype:

class A {}
Object.setPrototypeOf(A, Map.prototype)

Whoops, I definitely should have been able to figure that out. Thanks.