raiseToJump

[Matthew Fluet]

> > > Does this pass completely go away now in SSA? 
> > 
> > I think so.
> 
> I tracked down some of those unhandled options; the translation from CPS
> to SSA really has to do a trivial raiseToJump, to ensure that raises at
> non-empty handler stacks are turned into the appropriate jump.  This isn't
> currently going on (when I turn off all of the CPS simplification passes),
> so removeUnused in SSA is removing what looks like unused blocks.

Checked in a fix for this; I'm off.  I'll look at the regressions again
tomorrow.  This might have fixed a lot of them, particularly unhandled
exceptions.