cmd/compile: use []*Node instead of NodeList in bottomUpVisitor
This one of a set of changes to make the transition away from NodeList
easier by removing cases in which NodeList doesn't act semi-trivially like a
[]*Node.
This CL was originally prepared by Josh Bleecher Snyder <josharian@gmail.com>.
This change passes go build -toolexec 'toolstash -cmp' -a std.
Change-Id: I582ff8b077eb384b84721a1edb0c1efbc0c40059
Reviewed-on: https://go-review.googlesource.com/14304 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org> Reviewed-by: Dave Cheney <dave@cheney.net>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>