Implement NavigatorLanguage::languages

[Ms2ger]

Depends on #10072. (This implies we will not fix this issue in the near future.)

• Spec: https://html.spec.whatwg.org/multipage/#navigatorlanguage.
• Code: components/script/dom/webidls/Navigator.webidl, components/script/dom/navigator.rs, components/script/dom/webidls/WorkerNavigator.webidl, components/script/dom/workernavigator.rs.
• Tests: to be written, as far as I know.

[craftytrickster]

Do you mind if I take this?

[jdm]

@craftytrickster See the first sentence of the original comment.

[craftytrickster]

@jdm I'm not familiar with your use of webidl, but can't this at least be partially implemented with a Vector?

[jdm]

For #10072 specifically, the main reason to hold off implementing it is that Gecko has not and the FrozenArray feature is really new.

[craftytrickster]

Thanks for the info, nevermind me taking this then :)

[nox]

This has yet to be implemented.

[nox]

And it's blocked by #10072.

[jdm]

Closing in favour of #27210. We don't support frozen arrays in our codegen yet, but we can manually return a frozen array.