Noticed while addressing review feedback in UITour.jsm for a different bug, it hardcodes the ancestor of the back button as the urlbar-container ( https://dxr.mozilla.org/mozilla-central/rev/ef9a0f01e4f68214f0ff8f4631783b8a0e075a82/browser/components/uitour/UITour.jsm#137-140 ). This is no longer correct after bug 1363485. Not super clear to me if there's any bad consequences without diving in some more, for which I don't have time right now - if not, maybe we should just remove `widgetName`, otherwise it needs to be updated.

The widgetName is only used for filtering items within the app menu (which the back button never is), the backForard property is only used in tests which are all passing to looks like widgetName can be safely removed

Comment on attachment 8911864 [details] Bug 1386611 - Remove outdated widgetName from UITour. https://reviewboard.mozilla.org/r/183250/#review188468 Thanks for checking! I don't think this needs uplift unless we plan to highlight the back button as part of the UITour for 57, which I somewhat doubt. :-)

Pushed by dharvey@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/01ea5f8dcce0 Remove outdated widgetName from UITour. r=Gijs