chromium/third_party/blink/perf_tests/layout/multicol/nested-forced-breaks.html

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<script>
    var target = document.getElementById("target");
    var style = target.style;

    function test() {
        style.display = "block";
        PerfTestRunner.forceLayout();
        style.display = "none";
        PerfTestRunner.forceLayout();
    }

    PerfTestRunner.measureRunsPerSecond({
        description: "Measures performance of block fragmentation with deeply nested forced breaks.",
        run: test
    });
</script>