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.