Make RenderBlock have a protected constructor so that it cannot be instantiated directly.
Created attachment 210647 [details] Patch
Landed in r155141.
I had to roll this out with http://trac.webkit.org/changeset/155162 because of the failing tests.
(In reply to comment #3) > I had to roll this out with http://trac.webkit.org/changeset/155162 because of the failing tests. Reopen, since it was rolled out.
Re-landed this in r155211..