swift234

Change how we handle grouping parens.  Instead of (x) being ParenType(x),
it is now a single element TupleType(x).  In order to preserve sane behavior,
we force grouping parens to be non-canonical and have them desugar down to
their underlying element type.

This does cause an IRGen testcase failure that looks like it was just working
accidentally before (though I don't really understand what is going on).  I
filed rdar://10967479 to track it.


Swift SVN r1146