Finishes cleanup which was too late to do when discovered during the
Go 1.6 cycle.

Fixes #14291

Change-Id: Idc69fadbba10baf246318a22b366709eff088a75
Reviewed-on: https://go-review.googlesource.com/21360
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Andrew Gerrand <adg@golang.org>