See attached test case.
This was caused by http://trac.webkit.org/changeset/34681
In moveParagraphs, the style from the empty paragraph gets applied to the first line after the delete occurs.
I have a patch on the way...
Created attachment 29787 [details]
Created attachment 29788 [details]
This is the same as https://bugs.webkit.org/show_bug.cgi?id=24862 which Julie is actively working on. I think I remember her saying that there was a case in which the strategy you used wouldn't work, but you'll have to ask her for the specifics.
Hmm ok. I checked in revision 42869, but I'll move this discussion over to the other bug.