so basically @mounirlamouri says that we should set lang/dir on the translated dom nodes even if it was not here before, and even if it's not the direct target.

which does not answer the question about frames ;)

@fabi1cazenave the code would not kick in if window.frames.length is 0 anyway, so it would not slow down l10n.js for most applications. This would make l10n.js magically work for slide-based apps too ;)

If that's too expensive to access and translate all frames, maybe we can add a data marker on the frames that needs a translation ?