[test262] Add staging tests for isSubsetOf set method

This CL adds three tests to staging directory of test262.

Bug: v8:13556
Change-Id: Id6e468a0fa29528350a10c94e9dd19c2835788e8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5055866
Reviewed-by: Liviu Rau <liviurau@chromium.org>
Commit-Queue: Liviu Rau <liviurau@google.com>
Cr-Commit-Position: refs/heads/main@{#91139}

test/staging/set-is-subset-on-set-like.js

@@ -0,0 +1,24 @@
+// Copyright (C) 2023 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Test isSubsetOf set method on a set like with equal size.
+features: [set-methods]
+---*/
+
+const SetLike = {
+  arr: [42, 44, 45],
+  size: 3,
+  keys() {
+    return this.arr[Symbol.iterator]();
+  },
+  has(key) {
+    return this.arr.indexOf(key) != -1;
+  }
+};
+
+const firstSet = new Set();
+firstSet.add(42);
+firstSet.add(43);
+firstSet.add(45);
+
+assert.sameValue(firstSet.isSubsetOf(SetLike), false);

test/staging/set-is-subset-table-receiver-cleared.js

@@ -0,0 +1,25 @@
+// Copyright (C) 2023 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Test isSubsetOf set method receiver is cleared.
+features: [set-methods]
+---*/
+
+const firstSet = new Set();
+firstSet.add(42);
+firstSet.add(43);
+
+const otherSet = new Set();
+otherSet.add(42);
+otherSet.add(43);
+otherSet.add(47);
+
+Object.defineProperty(otherSet, 'size', {
+  get: function() {
+    firstSet.clear();
+    return 3;
+  },
+
+});
+
+assert.sameValue(firstSet.isSubsetOf(otherSet), true);

test/staging/set-is-subset-table-transition.js

@@ -0,0 +1,29 @@
+// Copyright (C) 2023 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+description: Test isSubsetOf set method after table transition in receiver.
+features: [set-methods]
+---*/
+
+const firstSet = new Set();
+firstSet.add(42);
+firstSet.add(43);
+firstSet.add(44);
+
+const setLike = {
+  size: 5,
+  keys() {
+    return [1, 2, 3, 4, 5].keys();
+  },
+  has(key) {
+    if (key == 42) {
+      // Cause a table transition in the receiver.
+      firstSet.clear();
+    }
+    // Return true so we keep iterating the transitioned receiver.
+    return true;
+  }
+};
+
+assert.sameValue(firstSet.isSubsetOf(setLike), true);
+assert.sameValue(firstSet.size, 0);