Use template_util.h in type_traits.h instead of reimplementing part of it.
Use template_util.h in type_traits.h instead of
reimplementing part of it.

R=csilvers
DELTA=34  (3 added, 31 deleted, 0 changed)


Revision created by MOE tool push_codebase.
MOE_MIGRATION=3343

LeslieW/sparsehash,LeslieW/sparsehash,LeslieW/sparsehash