enqueue(chunk) {
    if (!this.canCloseOrEnqueue()) {
      throw new TypeError(
          'Cannot enqueue a readable stream that has already been requested ' +
          'to be closed');
    }
    this.enqueueInternal(chunk);
  }
Enqueues a new chunk into the stream that can be read.
https://streams.spec.whatwg.org/#rs-default-controller-enqueue
@param {T} chunk
@override