test/custom_element_proxy_test.html

<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="dart.unittest" content="full-stack-traces">
  <title> custom_element_proxy test </title>
  <style>
     .unittest-table { font-family:monospace; border:1px; }
     .unittest-pass { background: #6b3;}
     .unittest-fail { background: #d55;}
     .unittest-error { background: #a11;}
  </style>
  <script src="/packages/web_components/webcomponents.js"></script>
  <script src="/packages/web_components/interop_support.js"></script>
  <script src="/packages/web_components/dart_support.js"></script>
</head>
<body>
  <h1> Running custom_element_proxy </h1>
  <div id="container"></div>

  <script>
    var basicElementProto = Object.create(HTMLElement.prototype);
    basicElementProto.isBasicElement = true;
    document.registerElement('basic-element', {
      prototype: basicElementProto
    });

    var extendedElementProto = Object.create(HTMLInputElement.prototype);
    extendedElementProto.isExtendedElement = true;
    document.registerElement('extended-element', {
      prototype: extendedElementProto,
      extends: 'input'
    });
  </script>

  <script type="text/javascript"
      src="/root_dart/tools/testing/dart/test_controller.js"></script>
  <script type="application/dart" src="custom_element_proxy_test.dart"></script>
  <script type="text/javascript" src="/packages/browser/dart.js"></script>
</body>
</html>