Should stringifiers have the `[ImplicitThis]` behaviour?

[ExE-Boss]

It feels weird to me that stringifiers don’t have the [ImplicitThis] behaviour that all other operations have as of #155.

[bzbarsky]

This only matters if someone adds a stringifier on a global object, right?

[ExE-Boss]

I guess so, also:

toString();
// returns "[object Undefined]"

globalThis.toString();
// returns "[object Window]"

[bzbarsky]

That's unrelated; it's invoking Object.prototype.toString, whose behavior is not governed by IDL at all.