chromium/third_party/blink/web_tests/editing/inserting/4960120-1.html

<p>This tests for a bug where the first newline entered into a text area would be lost.</p>
<textarea id="textarea"></textarea>

<script>
var textarea = document.getElementById("textarea");
textarea.setSelectionRange(0, 0);
textarea.focus();
document.execCommand("InsertLineBreak");
</script>