unicode/utf8: fix insignificant typos in tests
unicode/utf8: fix insignificant typos in tests

Fixes issue 4972.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/7649044

Committer: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go,abustany/go