title: RichText :inserthtml not working properly in Firefox
body: <p>I am trying to insert some text content at the cursor position in my contentEditable iframe
  for the following content(<code>&lt;span style='fontweight:bold'&gt;ab&lt;/span&gt;</code>)
  ab... Here i place the cursor after ab and if if i execute the following command
  <code>document.execCommand('insertHTML',false,"c")</code>
  The resulting html is as follows
  <code>&lt;span style='fontweight:bold'&gt;ab&lt;/span&gt;c</code></p>
  
  <p>What i required is 
  <code>&lt;span style='fontweight:bold'&gt;abc&lt;/span&gt;</code></p>
  
  <p>Note: This issue is only in Firefox, In chrome and safari i get the expected behavior which is needed for me.</p>
  
  <p>Please suggest a way to get this behavior in FF</p>