function toPoint(event) {

  if (event.pointers && event.pointers.length) {
    event = event.pointers[0];
  }

  if (event.touches && event.touches.length) {
    event = event.touches[0];
  }

  return event ? {
    x: event.clientX,
    y: event.clientY
  } : null;
}
@param {Event} event

@return {Point|null}