Function interval

docs/tests/v2/es6/js/sanddance.js:81156–81158

(date)

function newInterval(floori, offseti, count, field) {
  function interval(date) {
    return floori(date = arguments.length === 0 ? new Date() : new Date(+date)), date;
  }

  interval.floor = function (date) {
    return floori(date = new Date(+date)), date;