Bug 1112334 - Write a test for basic Find My Device logging in existing ...

...account
I think we can add https://moztrap.mozilla.org/manage/case/13663/ as a documentation and say this is a partial implementation of the test case.

Also I would a line to point to https://bugzilla.mozilla.org/show_bug.cgi?id=1112334#c7. So people would avoid to run this test more than 10 times.