POST_INTERP_RET: use a direct helper rather than service request
Summary:
There's no point in emitting a single service request stub inside unique stub
to multiplex the call just so that we can demultiplex it.
Eliminate all this unnecessary complexity and just call a direct C++ helper.
Move responsibilities for loading/storing various stuff between the unique stub
and the C++ helper to simplify both.
Reviewed By: ricklavoie
Differential Revision:
D27496111
fbshipit-source-id:
ad3f2db27798dadb1e57a250bba2eefda02a715c