The existing implementation names a c net.Conn return which is
never user. Leaving the returns unamed is marginally clearer.

Change-Id: If9a411c9235b78c116a8ffb21fef71f7a4a4ce8f
Reviewed-on: https://go-review.googlesource.com/66890Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>