`a.push(v)` where v may hold undefined at run time (an unchecked array
read or a hole-observing for-of binding, as in tsc-ts's filterType loop)
built a temporary one-element array, stored v or present undefined into
it, and spread it onto the receiver: an allocation, a growth, a copy and
two releases per append. Such pushes now evaluate every argument first,
then append each present value through the ordinary push (and its inline
dense fast path) and each missing one as a present-undefined slot at the
current length, which is what Node stores. Pure receivers and arguments
are re-read instead of copied into owned temporaries.
Call arguments read from arrays of nullable references now take the
inline dense lookup like other projections (the value is the element
pointer itself, so the path is a few loads), and scr_arr_peek_ref answers
dense in-range indices before the general lookup. compareSymbols'
`declarations[0]!` arguments no longer leave compiled code.
