while command line is a noun.

Change-Id: I9dfc2f6841d1171854857a8daa785d55afe2c5f3
Reviewed-on: https://go-review.googlesource.com/c/go/+/167783Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>