insertHTML destroyed html in selctedtext

<strong>Initial value</strong>

function getSelectionHTML(selection)
{
   var range = (document.all ? selection.createRange() : selection.getRangeAt(selection.rangeCount - 1).cloneRange());
   if (document.all)
   {
      return range.htmlText;
   }
   else
   {
      var clonedSelection = range.cloneContents();
      var div = document.createElement('div');
      div.appendChild(clonedSelection);
      return div.innerHTML;
   }
}

var mySelection = editor.getSelection();
var selectedText = getSelectionHTML(mySelection.getNative());
editor.insertHtml('<span style="color:red;">'+selectedText+'</span>');

<strong>Initial </strong><span style="color:red;">value</span><strong>.</strong>