It's no longer needed, as CSSRule and CSSStyleDeclaration both have it as a pure virtual member.
Created attachment 111799 [details] A patch
Comment on attachment 111799 [details] A patch r=me
Comment on attachment 111799 [details] A patch Clearing flags on attachment: 111799 Committed r98006: <http://trac.webkit.org/changeset/98006>
All reviewed patches have been landed. Closing bug.