Merge "Revert "Revert "Assembly RegionTLAB allocation fast path for x86_64"""
am: 266f2d4d51

* commit '266f2d4d51a18a703b2d4fbfedc63eb1baaf3ffb':
  Revert "Revert "Assembly RegionTLAB allocation fast path for x86_64""

Change-Id: I01706fea2b931de4e33c4eb10ee39d95d6aa1a6f