chromium/third_party/blink/web_tests/editing/spelling/spelling_after_newline.html

<!doctype html>
<script src="../../resources/testharness.js"></script>
<script src="../../resources/testharnessreport.js"></script>
<script src="../assert_selection.js"></script>
<script src="spellcheck_test.js"></script>

<script>
spellcheck_test(
  '<div contenteditable>|a</div>',
  document => {
    document.execCommand('insertText', false, 'x');
    document.execCommand('insertParagraph');
    document.execCommand('insertText', false, 'zz ');
  },
  '<div contenteditable>x<div>#zz# a</div></div>',
  'Mark misspelling in new line.'
);
</script>