Passes toolstash -cmp.

Change-Id: I325b02dcc8412ded0dc304d43377c0bdf59c66a8
Reviewed-on: https://go-review.googlesource.com/20405Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>