calendarAddYears function
Implementation
DateTime calendarAddYears(DateTime dt, int years) {
final y = dt.year + years;
final m = dt.month;
final d = dt.day;
final maxDay = _daysInMonth(y, m);
final day = d > maxDay ? maxDay : d;
return dt.isUtc
? DateTime.utc(y, m, day, dt.hour, dt.minute, dt.second, dt.millisecond, dt.microsecond)
: DateTime(y, m, day, dt.hour, dt.minute, dt.second, dt.millisecond, dt.microsecond);
}