port 257336d2 (r37297)

  original commit message:
  Replaces ArchDefault method with Crankshaft and Turbofan getters.
  Eliminates IsAllocated method on Register, FloatRegister, DoubleRegister.
  Eliminates ToString method too.
  Changes call sites to access appropriate arch default RegisterConfiguration.

BUG=

Review-Url: https://codereview.chromium.org/2114553002
Cr-Commit-Position: refs/heads/master@{#37413}