chromium/third_party/blink/web_tests/editing/execCommand/25256.html

<div id="description">This tests for https://bugs.webkit.org/show_bug.cgi?id=25256 where we would add a newline during an alignment change operation. You should see a single paragraph in the editable region below, and it should be right aligned.</div>
<div id="edit" contentEditable="true"><br></div>

<script>
edit = document.getElementById("edit");
edit.focus();
document.execCommand("JustifyRight");
if (window.testRunner) {
    testRunner.dumpAsText();
    document.body.innerText = document.getElementById("description").innerText + "\n\n" + edit.innerHTML;
}
</script>