ments with the specified tag name and specified attributes.</p>
<p>This will allow the elements as custom tags (such as &lt;x-foo&gt;&lt;/x-foo&gt;),
but will not allow tag extensions. Use <a href="polymer_app_layout/NodeValidatorBuilder/allowTagExtension.html">allowTagExtension</a> to allow
tag extensions.</p>
    
    </section>

    <section class="summary source-code" id="source">
      <h2>Source</h2>
      <pre><code class="prettyprint lang-dart">/**
 * Allow custom elements with the specified tag nam