keep both versions of china/taiwan localization icons (bug 1041520)

This fixes the immediate problem, but does highlight that we localize china and taiwan to cn / tw in some places and zh-cn / zh-tw in other places. I don't know how big a deal that is.
[the `fr` styles are missing](https://github.com/mozilla/fireplace/blob/master/src/media/css/site.styl#L445-L448). @diox added them in his PR #532.