Rich Text Editor Inserts Extra Lines using FireFox

To Reproduce

1. Use Firefox
2. Using Wiki Markup mode, enter the following text

   x
   
   y
   
   z

3. Save the page
4. Edit the page in Rich Text mode
5. Change 'y' to 'y y'
6. Save the Page
7. Look at the wiki markup

Expected Result

x

y y

z

Actual Result
Every time you add a space something else to the 'y' line, an extra blank line is inserted between the 'y' and 'z' lines, like this

x

y y


z

I think that https://studio.plugins.atlassian.com/browse/TBL-97 is actually an occurrence of this.

I've tested this in IE and Chrome. The behavior only occurs in Firefox.