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<html>
<head>
  <style>
    :read-only::-webkit-scrollbar {
      --a: var(--b), var(--c);
    }
  </style>
  <script>
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        testRunner.dumpAsText();
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        setTimeout(function() { document.write("Test passes if it does not crash."); testRunner.notifyDone(); });
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</head>
<body>
</body>
</html>