This implements the proposal described in
https://golang.org/issue/33848#issuecomment-537222782.

Fixes #33848

Change-Id: Ia34d6500ca396b6aa644b920233716c6b83ef729
Reviewed-on: https://go-review.googlesource.com/c/go/+/198319
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jay Conrod <jayconrod@google.com>