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;