encoding/runes: fixed unittest breakage

FullRune in core now correctly marks \xC0 and \xC1 as invalid starter
bytes for a rune. Adjust the tests accordingly.

Change-Id: Ie7bd53101dd5729a04e55ac1531d23ec247c06b6
Reviewed-on: https://go-review.googlesource.com/16941
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2 files changed