Revert "Remove dual-type support for Languages and Categories"

'Cos Parsoid caches things for ages.

This reverts commit 114a24f1d30571da248864dfdd53a1fbd08b5f4a.

Change-Id: I8b2f4d982becea36ddc06b29b3a48660fa0f3a44
Merge "Revert "Remove dual-type support for Languages and Categories""