Ensure we can reliably check the cell for validity of global property

test/mjsunit/regress/convert-global-data-to-accessor.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 f(o) {
+  return o.x;
+}
+this.x = 100;
+f(this);
+f(this);
+f(this);
+
+Object.defineProperty(this, 'x', { get: function() { return 10; }});
+assertEquals(10, this.x);
+assertEquals(10, f(this));
+
+function f2(o) {
+  return o.y;
+}
+
+f2(this);
+f2(this);
+f2(this);
+
+Object.defineProperty(this, 'y', { get: function() { return 10; }});
+assertEquals(10, this.y);
+assertEquals(10, f2(this));