CONSOLE WARNING: Synchronous XMLHttpRequest on the main thread is deprecated because of its detrimental effects to the end user's experience. For more help, check https://xhr.spec.whatwg.org/.
CONSOLE ERROR: XMLHttpRequest cannot load xmlhttprequest-no-file-access-expected.txt. Cross origin requests are only supported for protocol schemes: http, data, chrome, https.

The child iframe cannot paste its textual results into this iframe because it is considered a different domain - that's the point of this test! Therefore, success is denoted by the child iframe calling notifyDone. The test will hang if something goes amiss with the access control checks.