chromium/third_party/blink/web_tests/editing/execCommand/6444148.html

<div id="description">This tests applying style to a selection that ends with a line break.  Only the first paragraph should be styled.</div>
<div id="edit" contentEditable="true"><blockquote id="blockquote" type="cite">hello</blockquote>world</div>

<script>
if (window.testRunner)
    testRunner.dumpAsText();
blockquote = document.getElementById("blockquote");
edit = document.getElementById("edit");
description = document.getElementById("description");

window.getSelection().setBaseAndExtent(blockquote, 0, edit, 1);
document.execCommand("Bold");
if (window.testRunner)
    document.body.innerText = description.innerText + "\n\n" + edit.innerHTML;
</script>