Add this early in the cycle so that we can start regression testing
of the master toolchain.

Change-Id: Ida3ccad6e9642648f489babd12877fc8a5eca07a
Reviewed-on: https://go-review.googlesource.com/59151Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Joe Tsai <thebrokentoaster@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>