operator >= method
Compares two JDate base on their microsecondsSinceEpoch (millisecondsSinceEpoch if running on js environment)
Implementation
bool operator >=(JDate other) => isJs
? _millisecondsSinceEpoch >= other.millisecondsSinceEpoch
: _microsecondsSinceEpoch >= other.microsecondsSinceEpoch;