NoBody is new in Go 1.8.

Found while investigating #18117

Change-Id: I6bda030f358e2270f090d108cb3a89c8a2665fcb
Reviewed-on: https://go-review.googlesource.com/33714
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>