BR tag replacement seems to be to agressive

[Jakub Ś]

1. Use enter mode sample with allowedContent:true.
2. Paste below code into editor in Enter P or Div mode (in BR more some BR's are removed: #10497, #11392)

   <span>
   Some Text
   <br />
   <br />
   <br />
   </span>
   

3. Switch to WYSIWYG.

Results: BRs get extracted out side of span and changed into divs or paragraphs.

Problem can be reproduced from CKEditor 3.5.4 rev. [6740].

[Piotrek Koszuliński]

DUP of #12209.