ted");
    let beforeLoad = performance.now();
    let firstCallback = true;
    const url = window.location.origin + '/images/black-rectangle.png';
    const observer = new PerformanceObserver(
      t.step_func(entryList => {
        assert_equals(entryList.getEntries().length, 1);
        const entry = entryList.getEntries()[0];

        // First image is shrunk to be 10 x 10. The second image is added at its natural size: 100 x 50.
        const size = firstCallback ? 10 * 10 : 100 * 50;
        const i