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chromium/third_party/blink/web_tests/compositing/framesets/composited-frame-alignment.html 

<!DOCTYPE html>
<html>
<head>
  <title>Composited frame test</title>
  <style type="text/css" media="screen">
    #frame2 {
        position: absolute;
        left:100px;
        top:100px;
        padding: 0;
        height: 300px;
        width: 400px;
    }
  </style>
</head>
<frameset rows="*,400">
    <frame></frame>
    <frame id="frame2" src="resources/composited-subframe.html">
    </frame>
</frameset>
</html>