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.

lib/js/runtime.sx

@@ -2596,6 +2596,8 @@
         ((dict-has? obj skey) (get obj skey))
         ((dict-has? obj "__proto__")
           (js-dict-get-walk (get obj "__proto__") skey))
+        ((not (= obj (get Object "prototype")))
+          (js-dict-get-walk (get Object "prototype") skey))
         (else js-undefined)))))
 
 (define

lib/js/test262-scoreboard.json

@@ -1,26 +1,26 @@
 {
   "totals": {
-    "pass": 69,
-    "fail": 24,
+    "pass": 71,
+    "fail": 22,
     "skip": 1,
     "timeout": 6,
     "total": 100,
     "runnable": 99,
-    "pass_rate": 69.7
+    "pass_rate": 71.7
   },
   "categories": [
     {
       "category": "built-ins/String",
       "total": 100,
-      "pass": 69,
-      "fail": 24,
+      "pass": 71,
+      "fail": 22,
       "skip": 1,
       "timeout": 6,
-      "pass_rate": 69.7,
+      "pass_rate": 71.7,
       "top_failures": [
         [
           "Test262Error (assertion failed)",
-          12
+          10
         ],
         [
           "TypeError: not a function",
@@ -44,7 +44,7 @@
   "top_failure_modes": [
     [
       "Test262Error (assertion failed)",
-      12
+      10
     ],
     [
       "TypeError: not a function",
@@ -68,6 +68,6 @@
     ]
   ],
   "pinned_commit": "d5e73fc8d2c663554fb72e2380a8c2bc1a318a33",
-  "elapsed_seconds": 344.4,
+  "elapsed_seconds": 375.3,
   "workers": 1
 }

lib/js/test262-scoreboard.md

@@ -1,13 +1,13 @@
 # test262 scoreboard
 
 Pinned commit: `d5e73fc8d2c663554fb72e2380a8c2bc1a318a33`
-Wall time: 344.4s
+Wall time: 375.3s
 
-**Total:** 69/99 runnable passed (69.7%). Raw: pass=69 fail=24 skip=1 timeout=6 total=100.
+**Total:** 71/99 runnable passed (71.7%). Raw: pass=71 fail=22 skip=1 timeout=6 total=100.
 
 ## Top failure modes
 
-- **12x** Test262Error (assertion failed)
+- **10x** Test262Error (assertion failed)
 - **8x** TypeError: not a function
 - **6x** Timeout
 - **2x** Unhandled: Not callable: \\\
@@ -18,13 +18,13 @@ Wall time: 344.4s
 
 | Category | Pass | Fail | Skip | Timeout | Total | Pass % |
 |---|---:|---:|---:|---:|---:|---:|
-| built-ins/String | 69 | 24 | 1 | 6 | 100 | 69.7% |
+| built-ins/String | 71 | 22 | 1 | 6 | 100 | 71.7% |
 
 ## Per-category top failures (min 10 runnable, worst first)
 
-### built-ins/String  (69/99 — 69.7%)
+### built-ins/String  (71/99 — 71.7%)
 
-- **12x** Test262Error (assertion failed)
+- **10x** Test262Error (assertion failed)
 - **8x** TypeError: not a function
 - **6x** Timeout
 - **2x** Unhandled: Not callable: \\\