language: carry over all extensions Not just the āuā extension. Change-Id: Ia8fac679ecec066d1cd7af3f6b91d78010b3146a Reviewed-on: https://go-review.googlesource.com/55991 Run-TryBot: Marcel van Lohuizen <mpvl@golang.org> Reviewed-by: Nigel Tao <nigeltao@golang.org>