When the content of the editor is within a SPAN element, nested in a P, pasting data with P element inside it using the pasteHtml() method throws JavaScript errors and the SPAN element is broken by the nested P elements.

Steps to reproduce:
1.Set editor's content with this content: <p><span>Some text</span></p>

2.Use the editor's pasteHtml() method to paste this HTML in the middle of the above text: <p>Second text</p>

3.The result HTML is this:
<P><SPAN>Some</P>
<P>Second text</P>
<P>&nbsp;text</SPAN><SPAN>​</SPAN></P>