v8/test/mjsunit/harmony/regress/regress-405844.js

// Copyright 2014 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.
//
// Flags: --harmony-proxies --harmony-object-observe

var proxy = Proxy.create({ fix: function() { return {}; } });
Object.preventExtensions(proxy);
Object.observe(proxy, function(){});

var functionProxy = Proxy.createFunction({ fix: function() { return {}; } }, function(){});
Object.preventExtensions(functionProxy);
Object.observe(functionProxy, function(){});