The Tor Browser / file revision

 const Cu = Components.utils;

 function run_test() {

   // We rely on the crazy "wantXrays:false also causes values return from the

   // sandbox to be waived" behavior, because it's the simplest way to get

   // waivers out of the sandbox (which has no native objects). :-(

   var sb = new Cu.Sandbox('http://www.example.com', {wantXrays: false});

   Cu.evalInSandbox("this.foo = {}; Object.defineProperty(foo, 'bar', {get: function() {return {};}});", sb);

   do_check_true(sb.foo != XPCNativeWrapper(sb.foo), "sb.foo is waived");

   var desc = Object.getOwnPropertyDescriptor(sb.foo, 'bar');

   var b = desc.get();

   do_check_true(b != XPCNativeWrapper(b), "results from accessor descriptors are waived");

 }