[FF]: Problems with deleting last list item

[Jakub Ś]

I have found this issue when reproducing 8248

Scenario 1

1. Paste the following code:

   <ol>
   	<li> FirstListItem  </li>
   	<li> SecondListItem
   			<ol> 
   				<li> ThirdListItem  </li>
   				<li>  FourthListItem  </li>
   				<li>  FifthListItem  </li>
   			</ol>
   	</li>
   	<li> SixthListItem  </li>
   </ol>
   

2. Place the cursor before "sixth item" ^SixthListItem and press backspace

Result: You wont be able to delete "3".
NOTE: Webkit and Opera concatenates fith item with sixth item - FifthListItemSixthListItem. IE puts sixth item in new paragraph. Not sure which behavior is correct.

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Scenario 2

1. The same as above
2. Put the cursor behind fifth item FifthListItem^ and start pressing delete.

Result: When all text in sixth item gets deleted, number is deleted at the end.