Title: Add byte class to unicode class conversion for js

The upcoming rewrite of mw.Title needs to use wgLegalTitleChars,
but for that to work, it needs to be converted into something
that can work in javascript.

Signed-off-by: Timo Tijhof <krinklemail@gmail.com>
Signed-off-by: David Chan <david@sheetmusic.org.uk>
Change-Id: I163f3d7e3a680d52640a93f4bd195d8209669918
Merge "Title: Add byte class to unicode class conversion for js"