Find selection throws error on cut in IE6-8

[Jon Sykes]

Steps To Reproduce:

1. Go to the demo page in IE6 or IE7 or IE8.
2. Clear the content in the editor.
3. Type:

   foo bar
   boo far
   

4. Click on find icon
5. type foo into the find field
6. click find (foo will become selected)
7. click cancel in the find dialog
8. click 'cut' icon in ckeditor
9. (accept the permissions if the browser asks)
10. Error Invalid Argument gets thrown.

Looks like it's some issue with getting nodeValue (for nodeValue.length) within the GetRanges function of the selection plugin.

// Start the measuring until distance overflows, meanwhile count the text nodes.
var i = siblings.length;
while ( distance > 0 && i > 0 )
{
	sibling = siblings[ --i ];
	if ( sibling.nodeType == CKEDITOR.NODE_TEXT )
	{
		container = sibling;
		distance -= sibling.nodeValue.length;  <----- this line throws the error
	}
}

Same error occurs if you do a find a replace for foo then close the dialog and click cut.