test/Bugs/bug_OS17614914.js

//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------

Object.prototype.length = undefined;
var ary = Array();
ary.prop1 = 1;
Object.defineProperty(ary, "prop2", {
    value: 1,
    enumerable: false
});
for (var prop in ary) {
    if (prop !== "prop1") {
        console.log(`Fail: ${prop} property should not show in for-in`);
    }
}
console.log("pass");