title: google.script.host.close to close a dialog box not working
body: <p>I am trying to close a modeless dialog that I opened with the following:</p>
  
  <pre><code>var html = HtmlService.createHtmlOutputFromFile('dialog')
  .setSandboxMode(HtmlService.SandboxMode.IFRAME)
  .setWidth(150)
  .setHeight(150);
  DocumentApp.getUi().showModelessDialog(html, 'Help');
  </code></pre>
  
  <p>The dialog html looks like this</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
    &lt;html&gt;
     &lt;head&gt;
      &lt;base target="_top"&gt;
     &lt;/head&gt;
      &lt;body&gt;
       Working on it...
     &lt;/body&gt;
   &lt;/html&gt;
  </code></pre>
  
  <p>Now I want to close the dialog, but I can't get it to work.  This is what I have.</p>
  
  <pre><code>var html = HtmlService.createHtmlOutputFromFile('close');
  </code></pre>
  
  <p>And the close html looks like this:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
   &lt;html&gt;
     &lt;head&gt;
       &lt;base target="_top"&gt;
       &lt;script&gt;
         google.script.host.close();
       &lt;/script&gt;
     &lt;/head&gt;
     &lt;body&gt;
     &lt;/body&gt;
   &lt;/html&gt;
  </code></pre>
  
  <p>I've tried the google.script.host.close with the '()' and without.  Any ideas what I'm doing wrong?</p>
  
  <p>Thanks for your time!</p>