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chromium/third_party/blink/web_tests/paint/selection/first_letter/first_letter_1fr-expected.html 

<!doctype html>
<p><span style="font-size: 500%; color: red;">  [!(5)#]</span>9abcdefghi</p>
<script>
const selection = window.getSelection();
const sample = document.querySelector('p');
// Select "(5)#]9a"
selection.collapse(sample.firstChild.firstChild, 4);
selection.extend(sample.lastChild, 2);
</script>