List is incorrectly counting br

[Garry Yao]

Reproducing Procedures

1. Open the replace by class example page;
2. Make the following content with the selection by click 'Select All' command;

   ^text^
   

3. Click on 'Numbered List ' command to apply ;
   • Actual Result:

     <ol>
     	<li>
     		text</li>
     	<li>
                     <br />
     	</li>
     </ol>
     

   • Expected Result:

     <ol>
     	<li>
     		text</li>
     </ol>
     

[Garry Yao]

DUP of #3149

[Garry Yao]

After investigatoin, the bug is found to be caused by incorrectly counting bookmark nodes, which should be handled at #3352.