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chromium/third_party/blink/renderer/core/testing/data/mouse-wheel-overflow-body.html 

<!DOCTYPE HTML>
<head>
  <style>
    html {
      height: 100%;
      width: 100%;
      overflow-y: scroll;
    }

    body {
      height: 100%;
      width: 50%;
      margin: 0px 0px 100px 0px;
      overflow-y: scroll;
    }
  </style>
</head>
<body>
  <div style="height:1000px"></div>
</body>