LayoutTests/fast/flexbox/collapse-anonymous-wrappers-assertion.html

<style>
div {
  display: -webkit-box;
}
</style>

<div><div></div>PASS</div>

<br><br>

<span>
    WebKit Bug #<a href="https://bugs.webkit.org/show_bug.cgi?id=117176">117176</a>: Assertion below WebCore::FlexBoxIterator::next(). This test passes if it does not assert in a debug build.
</span>

<script>
    if (window.testRunner)
        window.testRunner.dumpAsText();

    style = document.getElementsByTagName("style")[0];
    style.innerText += "div:last-child { position: absolute; }";
</script>