title: Create a New HTML Document Including Doctype
body: <p>If I do:</p>
  
  <pre><code>let html = `&lt;!DOCTYPE html&gt;
  &lt;html&gt;
      &lt;head&gt;
          &lt;title&gt;Hello, world!&lt;/title&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;p&gt;Hello, world!&lt;/p&gt;
      &lt;/body&gt;
  &lt;/html&gt;`;
  
  let newHTMLDocument = document.implementation.createHTMLDocument().documentElement;
  
  newHTMLDocument.innerHTML = html;
  
  console.log( newHTMLDocument );
  </code></pre>
  
  <p>The output is:</p>
  
  <pre><code>&lt;html&gt;
      &lt;head&gt;
          &lt;title&gt;Hello, world!&lt;/title&gt;
      &lt;/head&gt;
      &lt;body&gt;
          &lt;p&gt;Hello, world!&lt;/p&gt;
      &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Why isn't the doctype tag included? What do I need to do so that when I output newHTMLDocument, it includes the doctype tag?</p>