Fix wrong merge conflict resolution (bug 1038985, bug 1039868)

See https://github.com/mozilla/fireplace/commit/57b14faa5b1bb97d4d37a846133bbdc67b680df0#commitcomment-7227864
Commit from Mozilla Verbatim by user theo.chevalier11@gmail.com.: 240 of 240 strings translated (0 fuzzy).
trigger `oncancel` when FxA popup actually closes (bug 1033698)