text: FAIL
  |  <!--
  |    Copyright 2019 The AMP HTML Authors. All Rights Reserved.
  |
  |    Licensed under the Apache License, Version 2.0 (the "License");
  |    you may not use this file except in compliance with the License.
  |    You may obtain a copy of the License at
  |
  |        http://www.apache.org/licenses/LICENSE-2.0
  |
  |    Unless required by applicable law or agreed to in writing, software
  |    distributed under the License is distributed on an "AS-IS" BASIS,
  |    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  |    See the License for the specific language governing permissions and
  |    limitations under the license.
  |  -->
  |  <!--
  |    Test Description:
  |    Only html attribute is allowed in <!doctype> declaration.
  |  -->
  |  <!doctype html data-foo id=doctype>
  >> ^~~~~~~~~
  amp4ads_feature_tests/doctype.html:20:0 Invalid or missing doctype declaration. Should be '!doctype html'. (see https://amp.dev/documentation/guides-and-tutorials/start/create/basic_markup/)
  |  <html ⚡4ads>
  |  <head>
  |    <meta charset="utf-8">
  |    <meta name="viewport" content="width=device-width,minimum-scale=1">
  |    <style amp4ads-boilerplate>body{visibility:hidden}</style>
  |    <script async src="https://cdn.ampproject.org/amp4ads-v0.js"></script>
  |  </head>
  |  <body>Hello, world.</body>
  |  </html>
  