Passes toolstash -cmp.

Change-Id: I2c204ec14b0a72b592fb336acdd4dff55650f7f6
Reviewed-on: https://go-review.googlesource.com/26751Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>