polyfill: parsing `UTCOffset` with sub-minute precision

[fabon-f]

Temporal.ZonedDateTime.from("2025-01-01T00:00:00+00:0000[Europe/London]");

In Firefox Nightly, this code raises an error (Uncaught RangeError: can't parse zoned date-time: time separator ':' must be consistent). But reference polyfill doesn't raise an error.

My understanding is that spec requires UTCOffset with sub-minute precision should be hh:mm:ss or hhmmss formats, which means the polyfill doesn't align the spec.

https://tc39.es/proposal-temporal/#prod-UTCOffset

[ptomato]

Thanks for the report. I think your understanding is correct. This should be fixed in the polyfill, but should also have test262 coverage added; the fact that it went unnoticed probably means it's not covered by tests.