Tighten up use of natives in QAST dumping.
Tighten up use of natives in QAST dumping.

Also, things end up simpler. This is in anticipation of a MoarVM patch
that tightens up int/num native parameters.

cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp,cygx/nqp