function joinDateAndTime_(date, time) {
  date = new Date(date);
  date.setHours(time.getHours());
  date.setMinutes(time.getMinutes());
  return date;
}
Creates a single Date object from separate date and time cells.

@param {Date} date A Date object from which to extract the date.
@param {Date} time A Date object from which to extract the time.
@return {Date} A Date object representing the combined date and time.