code: function endOfMonth() {
        var result = this.clone();
        result.day = ICAL.Time.daysInMonth(result.month, result.year);
        result.isDate = true;
        result.hour = 0;
        result.minute = 0;
        result.second = 0;
        return result;
      }
docs: Returns a copy of the current date/time, shifted to the end of the
  month.  The resulting ICAL.Time instance is of icaltype date, even if
  this is a date-time.
  
  @return {ICAL.Time}      The end of the month (cloned)