[dev.unified] cmd/compile/internal/noder: remove needType logic
[dev.unified] cmd/compile/internal/noder: remove needType logic

This logic is a holdover from very early on when it wasn't as clear
how we would handle dictionary entries for derived types, particularly
ones that are emitted during desugaring.

However, the current plan is to explicitly wire runtime type info
through IR nodes, so we can drop this logic.

Notably, the "needed" bit is exposed to the go/types importers, so
removing it would break the x/tools importer. To minimize churn for
now, we can just leave the bools in place.

Change-Id: I374927887d4f3d6d711d3355607849a407d717c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/413367
Reviewed-by: David Chase <ae171625adc8645b8b79b7e405a6da5aba5341e0@google.com>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Run-TryBot: Matthew Dempsky <e56ac2c500064424afac424d4b5e53bd0570a731@google.com>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go