test: write Go wrapper code so that bug302 can be run by run.go

Issue #4139.

Change-Id: I50d85a65b22c0cfb4d2a078cee45cf7adb23ba77
Reviewed-on: https://go-review.googlesource.com/1210
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>