Time zone abbreviation.
Offset from GMT in seconds. Defaults to -1 which means that first found time zone corresponding to abbr is returned. Otherwise exact offset is searched and only if not found then the first time zone with any offset is returned.
Daylight saving time indicator. Defaults to -1, which means that whether the time zone has daylight saving or not is not taken into consideration when searching. If this is set to 1, then the utcOffset is assumed to be an offset with daylight saving in effect; if 0, then utcOffset is assumed to be an offset without daylight saving in effect. If abbr doesn't exist then the time zone is searched solely by the utcOffset and isDST.
Returns time zone name on success or false on failure.