Return the length of the last day from NanosecondsToDays
Return the length of the last day from NanosecondsToDays

In case you need to round the remainder of nanoseconds to the nearest day,
you need to know how long the day is. This will be used to fix rounding
relative to a ZonedDateTime.

See: #1171

js-temporal/temporal-polyfill,js-temporal/temporal-polyfill,js-temporal/temporal-polyfill