Test for bug 5924 - zero-length responses to XMLHTTPRequest mishandled.
after creation: Uninitialized
ResponseText: ""
after setting onreadystatechange: Uninitialized
after open(): Open
after overrideMimeType(): Open
after send(): Loaded
Status: 200
StatusText: "OK"
ResponseText: ""
ResponseXML: null
ResponseXML serialized: n/a