The use of these has been removed in recent commits.

Change-Id: Iff36a3ee4dcdfe39c40e93e2601f44d3c59f7024
Reviewed-on: https://go-review.googlesource.com/33274
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>