gregorian property
Returns a Gregorian calendar system.
The Gregorian calendar system defines every fourth year as leap, unless the year is divisible by 100 and not by 400. This improves upon the Julian calendar leap year rule.
Although the Gregorian calendar did not exist before 1582 CE, this calendar system assumes it did, thus it is proleptic. This implementation also fixes the start of the year at January 1.
Implementation
static final CalendarSystem gregorian = _GregorianJulianCalendars.gregorian;