cmd/compile/internal/typecheck: merge SubstArgTypes into LookupRuntime
LookupRuntime is the only reason for using SubstArgTypes, and most
callers to LookupRuntime need to immediately call it anyway. So might
as well fuse them together.
Change-Id: Ie0724ed164b949040e898a2a77bea632801b64fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/521415 Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Auto-Submit: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Than McIntosh <thanm@google.com>