read() {
    if (!this.ownerReadableStream) {
      throw new TypeError(
          'This readable stream reader has been released and cannot be used ' +
          'to read from its previous owner stream');
    }
    return this.readInternal();
  }
Returns a Promise that resolves with an IIterableResult providing the next
chunk or that the stream is closed. The Promise may reject if the stream
is errored.
https://streams.spec.whatwg.org/#default-reader-read
@return {!Promise<!IIterableResult<T>>}
@override