function createArrayBufferResponse() {
  const headers = new Headers();
  headers.set('dummyHeader', 'dummyHeaderValue');
  headers.set('dummyHeader2', 'dummyHeaderValue2');
  return new Response(
      new ArrayBuffer(8), {status: 200, statusText: 'OK', headers: headers});
}
Creates a successful response with an ArrayBuffer payload.
@return {!Response}