The ids a zone picker offers, sorted, unique, UTC included: the runtime's
own table (Intl.supportedValuesOf('timeZone')) when it has one, else
FALLBACK_TIME_ZONE_IDS. The device zone is always on the list, and
so is current — the value the picker is showing — when it is a real zone,
so a stored id the fallback list does not carry still renders as selected
rather than as nothing.
The ids a zone picker offers, sorted, unique,
UTCincluded: the runtime's own table (Intl.supportedValuesOf('timeZone')) when it has one, else FALLBACK_TIME_ZONE_IDS. The device zone is always on the list, and so iscurrent— the value the picker is showing — when it is a real zone, so a stored id the fallback list does not carry still renders as selected rather than as nothing.