Phase 1 A.6.1 commit 1. Extends A.6.0's literal+ident type_
population to the CAST + TRY family + TYPEASSERT/TYPETEST arms in
exprtype. Mirrors cstage cmd/wcc/check.c:737 (N_CAST) and
1332-1435 (TYPETEST/TYPEASSERT/TRYPROP/TRYUNW) where n->type is
stamped on each value-returning path.
N_TRYPROP / N_TRYUNW only stamp the value-returning paths
(success-variant match inside the for-loop, no-error tail at
ou.list); the three nil-returning early-outs are intentionally
left unstamped.
Verified 132/132 incl. 995_self_rebuild byte-identity.
Hojun-Cho
c0fe38c101