fmt: update an old comment; fix a typo.
fmt: update an old comment; fix a typo.

R=golang-dev, iant
CC=golang-dev, minux.ma
https://codereview.appspot.com/6998055

Committer: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang,h8liu/golang