Revert to make josharians branch land cleanly

This reverts commit 38abd43b.

Change-Id: Idde1df953baf6e5742c87c4edd4bee0b6b418aca
Reviewed-on: https://go-review.googlesource.com/28480
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>