Lower all array bindings through intrinsic iterators and preserve symbol identity

[CaelmBleidd]

Array destructuring without a rest element used direct indices, so strings were split into UTF-16 units instead of JavaScript iterator values. Route all array binding patterns through the iterator, preserve defaults and elisions, and close partially consumed iterators using the actual return method and receiver. Return results must be objects; exceptional completion retains the original throw.

Preserve optional ITERATOR symbol provenance in EtsInstanceCallExpr and JSON for intrinsic spread, destructuring and synchronous for-of. Ordinary user methods remain distinct and legacy calls omit the metadata.

Independent against neo. Validation on final 5f32dae: frontend build/typecheck and 63 focused tests passed, including ten native-vs-IR destructuring/IteratorClose cases and five symbol-provenance cases. The original Kotlin symbol roundtrip gate passed; 28 closure/iterator tests additionally passed after updating obsolete index-based expectations, and final full CI passed. No upstream merge is included.

[github-actions]

Test Results

  239 files  ±0    239 suites  ±0   16m 10s ⏱️ + 2m 23s
  836 tests +1    824 ✅ +1  12 💤 ±0  0 ❌ ±0 
2 106 runs  +1  2 056 ✅ +1  50 💤 ±0  0 ❌ ±0 

Results for commit 5f32dae. ± Comparison against base commit bcad76f.

♻️ This comment has been updated with latest results.