constructor() {
    /** @type {function((T|!IThenable<T>|!Thenable)=)} */
    this.resolve;
    /** @type {function(*=)} */
    this.reject;

    /** @type {!Promise<T>} */
    this.promise = new Promise((resolve, reject) => {
      this.resolve = resolve;
      this.reject = reject;
    });
  }
Creates a new JavaScript native Promise and captures its resolve and reject
callbacks. The promise, resolve, and reject are available as properties
@final
@template T