me2 = document.createElement('iframe');
            document.head.appendChild(iframe2);
            document.head.removeChild(iframe1);
            document.head.removeChild(iframe2);
            const elm = document.getElementById('testPerformanceTimingNavigationStart');
            const perf = window.performance;
            const timing = perf.timing;
            const navigationStart = timing.navigationStart
            elm.textContent = navigationStart;
            elm.className = 'testPerformanceTimi