Enterkey on empty list item result weird

[garry.yao]

Reproducing Procedures

1. Open the 'replace by class' sample page.
2. Load the document with following content and selection:

   <table>
   	<tbody>
   	<tr>
   		<td>
   			<ol>
   				<li>item1
   					<ol>
   						<li>item2</li>
   						<li><br />^</li>
   					</ol>
   				</li>
   			</ol>
   		</td>
   	</tr>
   	</tbody>
   </table>
   

3. Press enter two times;
   • Actual Result: The result structure is in a mess;
   • Expected Result: The list keep unchanged with cursor stay at the end of list;

[garry.yao]

Actually it's a quite a serious bug, actually when the first enter is pressed, the DOM is already wrong, which shows that simply outdent the list as currently does is not enough:

<ol>
	<li>item1
		<ol>
			<li>item2</li>
		</ol>
		<li><br/></li>
	</li>
</ol>

[garry.yao]

Fixed with [3967].