feat: support virtual contexts

[43081j]

This adds support for virtual contexts by testing RegExp and Error via toString instead of an instanceof check.

cc @koddsson maybe you can help review and release?

[koddsson]

Hey sorry I'm late! Looks like the tests are failing.

[43081j]

ouch that's a tricky one!

class Foo extends Error {}

Foo.prototype === Error; // false

Foo.prototype instanceof Error; // true

Foo.prototype; // [Error]

Object.prototype.toString.call(Foo.prototype); // [object Object] <- why it fails

Object.getPrototypeOf(Foo) === Error; // true

ill have a think 🤔

[43081j]

@koddsson think i've fixed it!

i also reintroduced the instanceof checks so we do those first and fall back to using string comparisons

so we're not losing strictness for non-vm stuff (common use cases)

[koddsson]

Looks good to me :)