[FF] Create list result incorrect with Ctrl-A

[garry.yao]

Reproducing Procedures

1. Open the 'replace by class' sample page in Firefox;
2. Load the document with the following content and selection with Ctrl-A:

   [<p>line1</p>
   <p>line2</p>]
   

3. Click on 'Insert/Remove Bulleted List' button;
   • Actual Result: Four list items created.

[garry.yao]

Fixed with [3969].