fixup! assert,util: fix constructor lookup in deep equal comparison

Author: BridgeAR

test/parallel/test-assert-deep.js

@@ -1579,11 +1579,25 @@ test('Own property constructor properties should check against the original prot
   const b = { constructor: { name: 'Foo' } };
   assertDeepAndStrictEqual(a, b);
 
-  const prototype = {};
+  let prototype = {};
   Object.setPrototypeOf(a, prototype);
   Object.setPrototypeOf(b, prototype);
   assertDeepAndStrictEqual(a, b);
 
   Object.setPrototypeOf(b, {});
   assertNotDeepOrStrict(a, {});
+
+  prototype = { __proto__: null };
+  Object.setPrototypeOf(a, prototype);
+  Object.setPrototypeOf(b, prototype);
+  assertDeepAndStrictEqual(a, b);
+
+  Object.setPrototypeOf(b, { __proto__: null });
+  assert.notDeepStrictEqual(a, b);
+  assert.notDeepStrictEqual(b, a);
+
+  // Turn off no-restricted-properties because we are testing deepEqual!
+  /* eslint-disable no-restricted-properties */
+  assert.deepEqual(a, b);
+  assert.deepEqual(b, a);
 });