Self-compile and mlton.cm

[Stephen Weeks]

I recreated your bug.  The allocate registers pass actually finished -- the bug
is somewhere in the interaction between backend and allocate-registers.  Here's
the transcript (note that it says "allocate registers finished", not "allocate
registers raised").

   backend starting
      compute representations starting
      compute representations finished in 0.263
      inferHandlers starting
      inferHandlers finished in 0.405
      chunkify starting
      chunkify finished in 1.688
      allocate registers starting
      allocate registers finished in 76.011
      reg size is 4,384 bytes
   backend raised in 96.207
compile raised in 654.006
mlton: x_221 has no operand property

Anyways, this should be an easy one to find, if not fix.  I'll send mail
shortly.