js-on-sx: js-dict-get-walk falls back to Object.prototype

Object literals didn't carry a __proto__ link, so ({}).toString()
couldn't reach Object.prototype.toString. Added a cond clause: if
the object has no __proto__ AND is not Object.prototype itself,
walk into Object.prototype. Now ({}).toString() works, override
of Object.prototype.toString propagates, and ({a:1}).hasOwnProperty
('a') returns true. built-ins/String: 69/99 → 71/99 (canonical),
71/99 → 74/99 (isolated). conformance.sh: 148/148.

plans/js-on-sx.md

@@ -158,6 +158,8 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 
 Append-only record of completed iterations. Loop writes one line per iteration: date, what was done, test count delta.
 
+- 2026-05-07 — **`js-dict-get-walk` falls back to `Object.prototype` when an object has no `__proto__`.** Object literals (`{}`, `{a:1}`) didn't carry a `__proto__` link, so `({}).toString()` couldn't find `Object.prototype.toString` — and overriding `Object.prototype.toString` had no effect on plain objects. Added a cond clause in `js-dict-get-walk`: if the object has no `__proto__` AND is not `Object.prototype` itself, walk into `Object.prototype`. Termination guaranteed because Object.prototype is the recursion base case. Now `({}).toString() === "[object Object]"`, override of `Object.prototype.toString` propagates to plain objects, and `({a:1}).hasOwnProperty('a') === true`. built-ins/String: 69/99 → 71/99 (canonical), 71/99 → 74/99 (isolated). conformance.sh: 148/148.
+
 - 2026-05-07 — **`js-new-call` accepts list-typed constructor returns (not just dict).** `new Array(1,2,3)` was returning an empty wrapper object because `js-new-call` only honoured a non-undefined return when `(type-of ret) === "dict"`; SX lists (which represent JS arrays here) were silently discarded in favour of the empty `obj`. Widened the check to accept `"list"` returns. Fixes `new Array(1,2,3).length`, `String(new Array(1,2,3))`, and any constructor whose body returns a list. built-ins/String 67/99 → 69/99 (canonical), 70/99 → 71/99 (isolated). conformance.sh: 148/148.
 
 - 2026-05-07 — **`js-num-from-string` uses `pow` (float) instead of `js-pow-int` for the exponent.** Numeric literals like `1e20` and `100000000000000000000` were parsing as `-1457092405402533888` because `js-pow-int 10 20` overflows int64 (10^20 > 2^63). The OCaml SX `pow` primitive uses float-domain power and produces `1e+20` correctly. Replaced the single `(js-pow-int 10 e)` call in `js-num-from-string` with `(pow 10 e)`. Fixes `String(1e20)`, `String(1e30)`, `String(100000000000000000000)`, etc. With isolation built-ins/String 67/99 → 70/99. conformance.sh: 148/148.