function createOrUpdate(minX, minY, maxX, maxY, dest) {
  if (dest) {
    dest[0] = minX;
    dest[1] = minY;
    dest[2] = maxX;
    dest[3] = maxY;
    return dest;
  }
  return [minX, minY, maxX, maxY];
}
Create a new extent or update the provided extent.
@param {number} minX Minimum X.
@param {number} minY Minimum Y.
@param {number} maxX Maximum X.
@param {number} maxY Maximum Y.
@param {Extent} [dest] Destination extent.
@return {Extent} Extent.