Doc vs polyfill mismatch for timeZone.getOffsetStringFor(), expected string should not show seconds.

[Louis-Aime]

The documentation on Temporal.TimeZone says:

This method is similar to timeZone.getOffsetNanosecondsFor(), but returns the offset formatted as a string, with sign, hours, and minutes.

However, the polyfill may add seconds:
mytz = new Temporal.TimeZone('Europe/Paris');
mytz.getOffsetStringFor('1900-02-01T12:00Z'); // '00:09:21'

It should probably round to the nearest minute before computing the string (to be specified).