Doesn't handle <br><br> within <strong></strong>

[bkazez]

ReverseMarkdown.convert("<strong>hello<br><br>world</strong>")

=>

**hello  
  
world** 

Expected:

**hello**  
  
**world**  

[directionless]

Related:

[70] pry(main)> ReverseMarkdown.convert '<h1>foo<br>bar</h1>'

=> "# foo  \nbar\n"