LayoutTests/fast/html/details-mathml-crash.html

This test passes if it doesn't crash.
<div><br><summary><mrow></mrow><br>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
document.execCommand("SelectAll", false, null);
var style = document.createElement("style");
style.innerHTML="* { position: absolute; }";
document.getElementsByTagName("head")[0].appendChild(style);
</script>