This makes this code better self-documenting and makes it easier to
find these places in the future.

Change-Id: I31dc5598ae67f937fb9ef26df92fd41d01e983c3
Reviewed-on: https://go-review.googlesource.com/22631Reviewed-by: Rick Hudson <rlh@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>