Tests for bug 7877: XMLHttpRequest ignores username/password passed to open()

sync: User: sync, password: 123.
sync2: User: sync2, password: 123.
sync3: User: sync3, password: 123.
sync4: User: sync4, password: 123.
async: User: async, password: 123.
async2: User: async2, password: 123.
async3: User: async3, password: 123.
async4: User: async4, password: 123.