chromium/third_party/blink/web_tests/paint/selection/text-selection-editing-crash.html

<!doctype html>
<style>
.box {
    height: 100px;
    -webkit-user-modify: read-only;
}
</style>
<script>
</script>
Test passes if it does not CRASH.
<div class="box">
<script>
if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.waitUntilDone();
}

document.designMode = 'on';
document.execCommand("selectAll");
document.execCommand("selectAll");
document.execCommand("formatblock", false, "h1");
document.execCommand("InsertHTML", false, "<blockquote type='cite'>xxxx xxxxxx xxx xx blockquoted.</blockquote>");
document.execCommand("InsertText", false, "xxxxxxxxxxxxxxxxxxx");
document.execCommand("FindString", true, "d");
document.execCommand("selectAll");
document.execCommand("forwardDelete");

window.requestAnimationFrame(function() {
    testRunner.notifyDone();
});
</script>