title: Make CKEditor ignore widget content
body: <p>The HTML inside the <code>aside</code> isn't editable but CKEditor still runs the content filter and removes tags and shows hidden input fields.</p>
  
  <p>The relevant HTML widget code is as follows:</p>
  
  <pre><code>&lt;aside class="widget widget-form" contenteditable="false" data-widget-id="12" id="widget-4564" style="width: 40%; float: left;"&gt;
      // my form HTML goes here
  &lt;/aside&gt;
  </code></pre>
  
  <p>The relevant CKEditor widget code is as follows:</p>
  
  <pre><code>template : 
      '&lt;aside class="widget" contenteditable="false" style="width: 50%; float: left;" id="widget-'+Date.now().toString().substring(Date.now().toString().length-4)+'"&gt;\
          New Widget\
      &lt;/aside&gt;',
  allowedContent : true,
  upcast: function( element ) {
      if ( element.name == 'aside' &amp;&amp; element.hasClass( 'widget' ) )
          return true;
  },
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/3Pzfq.png" alt="enter image description here"></p>