The gofrontend crashed importing a complex 0 constant.
For #52862
Change-Id: Ia87d8eadb9c5ddf51e1cd65c1a626f05f0d068d4
Reviewed-on: https://go-review.googlesource.com/c/go/+/413980
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
