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chromium
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chromium/third_party/blink/web_tests/virtual/text-antialias/firstline/001.html 

<html>
<head>
<style>
p:first-line {
  color: green;
  font-size: 50px;
}
</style>
<body><p>BigAndGreen<br>SmallAndBlack</p></body>
</html>