The Tor Browser / file revision

 var objectProxy = Proxy.create({});

 var functionProxy = Proxy.createFunction({}, function() {}, function() {});

 assertEq(Object.prototype.toString.call(objectProxy), '[object Object]');

 assertEq(Object.prototype.toString.call(functionProxy), '[object Function]');

 assertEq(Function.prototype.toString.call(functionProxy), 'function () {}');

 try {

   Function.prototype.toString.call(objectProxy);

   assertEq(true, false);

 } catch (e) {

   assertEq(!!/incompatible/.exec(e), true);

 }