chromium/chrome/test/data/chromedriver/attribute_colon_test.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Test Attribute with escape characters</title>
  </head>
  <body>
    <select name="phones" size="3" onchange="alert('hello');" ext:qtip="colonvalue">
      <option value="iphone">Apple IPhone</option>
      <option value="android">Google Android</option>
      <option value="wp">MS Windows Phone</option>
    </select>
  </body>
</html>