CONSOLE WARNING: line 62: 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/.
Test that XMLHttpRequest raises exceptions when it should.

new XMLHttpRequest()
PASS: req.setRequestHeader("Foo", "bar") threw exception InvalidStateError: Failed to execute 'setRequestHeader' on 'XMLHttpRequest': The object's state must be OPENED..
PASS: req.send(null) threw exception InvalidStateError: Failed to execute 'send' on 'XMLHttpRequest': The object's state must be OPENED..
open()
PASS: req.setRequestHeader() threw exception TypeError: Failed to execute 'setRequestHeader' on 'XMLHttpRequest': 2 arguments required, but only 0 present..
PASS: req.setRequestHeader("Foo") threw exception TypeError: Failed to execute 'setRequestHeader' on 'XMLHttpRequest': 2 arguments required, but only 1 present..
send()
PASS: req.send(null) threw exception InvalidStateError: Failed to execute 'send' on 'XMLHttpRequest': The object's state must be OPENED..
PASS: req.setRequestHeader("Foo", "bar") threw exception InvalidStateError: Failed to execute 'setRequestHeader' on 'XMLHttpRequest': The object's state must be OPENED..
PASS: req.getResponseHeader() threw exception TypeError: Failed to execute 'getResponseHeader' on 'XMLHttpRequest': 1 argument required, but only 0 present..
PASS: req.open() threw exception TypeError: Failed to execute 'open' on 'XMLHttpRequest': 2 arguments required, but only 0 present..
PASS: req.open(null) threw exception TypeError: Failed to execute 'open' on 'XMLHttpRequest': 2 arguments required, but only 1 present..