Take Symbol-keyed properties into account in Object.freeze and friends

test/mjsunit/regress/regress-539875.js

+// Copyright 2015 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+(function testSeal() {
+  var sloppy = arguments;
+  var sym = Symbol();
+  sloppy[sym] = 123;
+  Object.seal(sloppy);
+  assertTrue(Object.isSealed(sloppy));
+  var desc = Object.getOwnPropertyDescriptor(sloppy, sym);
+  assertEquals(123, desc.value);
+  assertFalse(desc.configurable);
+  assertTrue(desc.writable);
+})();
+
+
+(function testFreeze() {
+  var sloppy = arguments;
+  var sym = Symbol();
+  sloppy[sym] = 123;
+  Object.freeze(sloppy);
+  assertTrue(Object.isFrozen(sloppy));
+  var desc = Object.getOwnPropertyDescriptor(sloppy, sym);
+  assertEquals(123, desc.value);
+  assertFalse(desc.configurable);
+  assertFalse(desc.writable);
+})();
+
+
+(function testIsFrozenAndIsSealed() {
+  var sym = Symbol();
+  var obj = { [sym]: 123 };
+  Object.preventExtensions(obj);
+  assertFalse(Object.isFrozen(obj));
+  assertFalse(Object.isSealed(obj));
+})();