chromium/third_party/blink/web_tests/fast/events/resources/mousedown-in-subframe-scrollbar.html

<body contentEditable>
<p id="p">
  This<br/>
  is<br/>
  text<br/>
  to<br/>
  force<br/>
  a<br/>
  vertical<br/>
  scrollbar<br/>
  to<br/>
  appear.<br/>
</p>
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