chromium/third_party/blink/web_tests/dom/mutation-event-tests/fast/css/first-letter-range-insert.html

<!DOCTYPE html>

<style>
div:first-child {
  -webkit-column-count:65540;
}
div:first-letter {
  color: green;
}
</style>
<script>
if (window.testRunner)
    testRunner.dumpAsText();
document.addEventListener("readystatechange", function() {
  document.execCommand("SelectAll")
  window.getSelection().deleteFromDocument();
});

document.addEventListener("DOMCharacterDataModified", modifiedListener);
function modifiedListener(evt) {
  document.removeEventListener("DOMCharacterDataModified", modifiedListener);
  window.getSelection().getRangeAt(0).insertNode(document.getElementById('dfn'));
}
</script>
<body>
<!-- Passes if no CRASH in debug. -->

<dfn id='dfn'></dfn>

<span>
<div id='node'>
c B
</div>
</span>
</body>