swift234

Shuffle around some of the optimization passes.

The end goal here is to end up with a good pass ordering that will allow
us to only run one set of these passes, rather than running them
twice. This is a start in that direction.

No real impact measured on compile times as of this change. On
benchmarks I see a mix of regressions and improvements.

-O improvements:
  Calculator           -17.6%     1.21x
  Chars                -54.4%     2.19x
  PolymorphicCalls     -14.7%     1.17x
  SetIsSubsetOf        -14.1%     1.16x
  Sim2DArray           -14.1%     1.16x
  StrToInt             -30.4%     1.44x

-O regressions:
  CaptureProp          +32.9%     0.75x
  DictionarySwap       +36.0%     0.74x
  XorLoop              +39.8%     0.72x

-Ounchecked improvements:
  Chars                -58.0%     2.38x

-Ounchecked regressions:
  CaptureProp          +33.3%     0.75x

-Onone improvements:
  StrToInt             -14.9%     1.18x
  StringWalk           -47.6%     1.91x
  StringWithCString    -17.2%     1.21x
  (many more smaller improvements)

-Onone regressions:
  Calculator           +21.5%     0.82x
  OpenClose            +10.1%     0.91x