Tests for Intl DurationFormat API

[romulocintra]

Hi, opening this issue as a placeholder/reminder for the Intl.DurationFormat tests that advanced to Stage 3 in TC39 2021 October meeting.

https://github.com/tc39/proposal-intl-duration-format

Checklist

• [x] Basic checks (name, length, prop-desc, slot)
• [x] Intl.DurationFormat.prototype.constructor
• [x] Intl.DurationFormat.prototype [ @@toStringTag ]
• [x] Intl.DurationFormat.prototype.format
• [x] Intl.DurationFormat.prototype.formatToParts
• [x] Intl.DurationFormat.prototype.resolvedOptions
• [ ] ...

[jugglinmike]

Thanks, Romulo! If anyone is interested in writing these tests, please comment here. That will help us avoid duplicating effort.

[EarthyOrange]

@jugglinmike I can help out with this.

• Is this feature already implemented (partially?) in any engine available under esvu which I can use to write tests?
• If so then is there a flag under which it is being hidden?
• If not then should I just add (failing) tests based on the proposal?

[EarthyOrange]

@jugglinmike Can you please take a look at the PR?

[FrankYFTang]

intl402/DurationFormat/constructor-options-defaults.js need to be changed to sync with the changes landed in https://github.com/tc39/proposal-intl-duration-format/pull/185 @ben-allen