OIOTA used to be used to represent "iota" in the pre-typechecked IR,
before we knew whether it was safe to replace it with a constant
(because it could be redefined as a global symbol later).
However, now types2 handles constant folding, including handling of
"iota". So this can go away.
Updates #51691.
Change-Id: I3cec45b22c4c8f1c357dcc4003292c21ae32aa90
Reviewed-on: https://go-review.googlesource.com/c/go/+/393255
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>