constructor() {
    /**
     * A sizing algorithm that takes a chunk of the ReadableStream and returns
     * a size.
     * https://streams.spec.whatwg.org/#qs-api
     * @type {(function(T): number)|undefined}
     */
    this.size;

    /**
     * Used to calculate the desired size of the ReadableStream. The high-water
     * mark minus the sum of the sizes of chunks currently in the queue is the
     * desired size.
     * https://streams.spec.whatwg.org/#qs-api
     * @type {number|undefined}
     */
    this.highWaterMark;
  }
The strategy for the ReadableStream queue.
@template T
@record