Remove list broken with enterMode = BR

[Garry Yao]

Originally reported by Martin, this related to #3773, but not a DUP.

1. Open the replace by code example page with enterMode = BR;
2. Make the content and selection as below:

   line1
   <ul><li>[item1</li><li>item2]</li></ul>
   line2
   

3. Click on 'Bullet List' to remove list;
   • Expected Result:

     line1<br />
     item1<br />
     item2<br />
     line2
     

   • Actual Result:

     line1item1item2line2