Bug 980638 - Show error message on forgot password click in FxA during FTU r=ferjm

  * Also prevents opening an unclosable web browser from COPPA error screen
    in the FxA FTU flow.
Merge pull request #18657 from 6a68/bug-980638-fxa-ftu-reset-password-fix

Bug 980638 - Show error message on forgot password click in FxA during FTU