Find references to identifiers in both a package and its test package.
Change-Id: I9d9da4aa37c36c448336aed044df79cfd1c903f1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/183990
Run-TryBot: Suzy Mueller <suzmue@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>