title: document.execCommand('insertHtml') not working twice when line is empty
body: <p>When i use document.execCommand(insertHTML) twice (e.g. hitting enter twice to insert new paragraph) nothing will happen. So only one new line is created.</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;div id="editor" contenteditable="true"&gt;&lt;p&gt;Some text&lt;/p&gt;&lt;/div&gt;
  </code></pre>
  
  <p>JS:</p>
  
  <pre><code>$('#editor').on('keyup keydown keypress',function(e){
      if(e.keyCode === 13){
      document.execCommand("insertHTML",false,"&lt;p&gt;&lt;br&gt;&lt;/p&gt;");
      return false;
      }
  });
  </code></pre>
  
  <p>So how can i create two new empty paragraphs when the user hits twice enter?</p>
  
  <p>See also fiddle: <a href="http://jsfiddle.net/auvnbz5o/" rel="nofollow">http://jsfiddle.net/auvnbz5o/</a> (hit enter twice and nothing will happen - only when u enter a character a new paragraph can be created)</p>