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.
I had the same question on IRC - `zh-cn` and `zh-tw` aren't referenced anywhere as region as far as I can see, so I don't understand why we have them.