Hopefully, this fixes https://github.com/vector-im/vector-web/issues/1046
without any side-effects.
It relies on the fact that the languages files are pretty simple - in
particular, they don't require any other modules. So we can tell webpack just
to suck them in as they are, rather than parsing them and causing an explosm.
Webapck actually supports loading input source maps and generally seems a lot
more solid then browserify (even if their website has an annoying animated
logo).