redundant

[Stephen Weeks]

> I ported redundant from CPS to SSA.  Seems to work on all of the
> regressions.  Spot checking a few regressions and benchmarks, it doesn't
> seem to do much in practice.  Is it really cleaning up after one of the
> other simplification passes?

The reason redundant got put in was due to some output of the closure
converter where the environment record, or components of it, were
passed around in several places.  That may have been more relevant
with polyvariant analyses (which are long gone).  But it still seems
possibly relevant, especially with more aggressive flattening, which
should reveal some fields in nested closure records that are
redundant.