Test that XMLHttpRequest raises exceptions when it should.

new XMLHttpRequest()
PASS: req.setRequestHeader("Foo", "bar") threw exception Error: INVALID_STATE_ERR: DOM Exception 11.
PASS: req.send(null) threw exception Error: INVALID_STATE_ERR: DOM Exception 11.
open()
PASS: req.setRequestHeader() threw exception TypeError: Not enough arguments.
PASS: req.setRequestHeader("Foo") threw exception TypeError: Not enough arguments.
PASS: req.status() threw exception Error: INVALID_STATE_ERR: DOM Exception 11.
PASS: req.statusText() threw exception Error: INVALID_STATE_ERR: DOM Exception 11.
send()
PASS: req.send(null) threw exception Error: INVALID_STATE_ERR: DOM Exception 11.
PASS: req.setRequestHeader("Foo", "bar") threw exception Error: INVALID_STATE_ERR: DOM Exception 11.
PASS: req.getResponseHeader() threw exception TypeError: Not enough arguments.