Drop the computed Array.isArray refusal from the stdlib fence snapshot

`Array.isArray([1])` folds after evaluating its argument, so the stdlib
fence battery no longer reports SC1090 for it. The snapshot drops that
diagnostic and the statement notes that it lowers.

tests/diagnostics/stdlib-fence.ts

@@ -12,7 +12,7 @@ const g = globalThis;
 const nan = NaN; // lowers now — a non-finite numeric literal like Infinity
 const s5 = String(5);
 const n5 = Number.NaN; // lowers now, with the other Number constants
-const isArr = Array.isArray([1]);
+const isArr = Array.isArray([1]); // lowers now: a computed argument folds after it is evaluated
 const merged = Object.assign({}, { a: 1 }); // the empty-target literal-source shape lowers now (it IS the source literal)
 const aliasedAssign = Object.assign(merged, { b: 2 }); // aliased targets stay fenced (real mutation of a live object)
 const refl = Reflect.has({ a: 1 }, "a");

tests/harness/__snapshots__/stdlib-fence.ts.txt

@@ -1,10 +1,3 @@
-stdlib-fence.ts:15:15 - error SC1090: statically-decided Array.isArray on computed arguments (bind the value to a variable first) are not supported yet
-
-  14 | const n5 = Number.NaN; // lowers now, with the other Number constants
-  15 | const isArr = Array.isArray([1]);
-     |               ^~~~~~~~~~~~~~~~~~
-  16 | const merged = Object.assign({}, { a: 1 }); // the empty-target literal-source shape lowers now (it IS the source literal)
-
 stdlib-fence.ts:17:23 - error SC2020: 'Object.assign' is part of the standard library types but has no scriptc lowering yet
 
   16 | const merged = Object.assign({}, { a: 1 }); // the empty-target literal-source shape lowers now (it IS the source literal)