The Tor Browser / file revision

 // |reftest| skip-if(!xulRuntime.shell)

 // Any copyright is dedicated to the Public Domain.

 // http://creativecommons.org/licenses/publicdomain/

 // Contributor: Blake Kaplan

 function expect(actual, arg) {

     reportCompare(expect.expected, actual, arg);

 }

 var window = { set x(y) { expect(this, y) }, y: 4 };

 expect.expected = window;

 window.x = "setting through a setter directly";

 window.y = 5;

 reportCompare(5, window.y, "setting properties works");

 var easy = { easy: 'yes', __proto__: window }

 expect.expected = easy;

 easy.x = "setting through a setter all-native on prototype";

 easy.y = 6;

 reportCompare(5, window.y, "window.y remains as it was");

 reportCompare(6, easy.y, "shadowing works properly");

 var sandbox = evalcx('');

 sandbox.window = window;

 sandbox.print = print;

 sandbox.expect = expect;

 var hard = evalcx('Object.create(window)', sandbox);

 expect.expected = hard;

 hard.x = "a setter through proxy -> native";

 hard.y = 6;

 reportCompare(5, window.y, "window.y remains as it was through a proxy");

 reportCompare(6, hard.y, "shadowing works on proxies");

 hard.__proto__ = { 'passed': true }

 reportCompare(true, hard.passed, "can set proxy.__proto__ through a native");

 var inverse = evalcx('({ set x(y) { expect(this, y); }, y: 4 })', sandbox);

 expect.expected = inverse;

 inverse.x = "setting through a proxy directly";

 inverse.y = 5;

 reportCompare(5, inverse.y, "setting properties works on proxies");

 var inversehard = Object.create(inverse);

 expect.expected = inversehard;

 inversehard.x = "setting through a setter with a proxy on the proto chain";

 inversehard.y = 6;

 reportCompare(5, inverse.y, "inverse.y remains as it was");

 reportCompare(6, inversehard.y, "shadowing works native -> proxy");

 inversehard.__proto__ = { 'passed': true }

 reportCompare(true, inversehard.passed, "can set native.__proto__ through a proxy");