[window.html]
  expected:
    if not debug and (os == "linux") and webrender and not fission: ["ERROR", "OK"]
    if not debug and (os == "win") and (processor == "x86"): ["ERROR", "OK"]
    if debug and (os == "win") and webrender: ["ERROR", "OK"]
    if debug and (os == "linux") and not fission: ["ERROR", "OK"]
    if debug and (os == "mac"): ["ERROR", "OK"]
    [OK, ERROR]
  [transfer to and from an iframe should work]
    expected: FAIL

  [the same ReadableStream posted multiple times should arrive together]
    expected: FAIL

  [port.postMessage should be able to transfer a ReadableStream]
    expected: FAIL

  [window.postMessage should be able to transfer a ReadableStream]
    expected: FAIL