I made a silly-looking mess with Document::m_styleResolverThrowawayTimer, there's a better ready-made abstraction.
Created attachment 201379 [details] Patch
Comment on attachment 201379 [details] Patch Clearing flags on attachment: 201379 Committed r150013: <http://trac.webkit.org/changeset/150013>
All reviewed patches have been landed. Closing bug.