<!DOCTYPE html> <meta charset=utf-8> <title>Test for ...</title> <script src="/resources/testharness.js"></script> <script src="/resources/testharnessreport.js"></script> <div id="log"></div> <script> test(function() { assert_throws(new TypeError, function() { Object.setPrototypeOf(window, Object.create(window)); }, "Setting prototype via setPrototypeOf"); assert_throws(new TypeError, function() { window.__proto__ = Object.create(window); }, "Setting prototype via __proto__"); }, "Setting the prototype of a window to something that has the window on its proto chain should throw"); </script>