cmd/compile: simplify outerfn check in closureName
Since CL 523275, outerfn is always non-nil.
Change-Id: I42cfff90546e506e04a74fb4f754a25f1eadddc9
Reviewed-on: https://go-review.googlesource.com/c/go/+/598636 Reviewed-by: Than McIntosh <thanm@google.com>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>