When enabling seamless iframes fast/regions/seamless-iframe-flowed-into-regions.html fails. This happens because the RenderFlowThread objects are shared between the root RenderView and the iframe RenderView but they have different layout state objects.
Created attachment 205161 [details]
Comment on attachment 205161 [details]
Clearing flags on attachment: 205161
Committed r151992: <http://trac.webkit.org/changeset/151992>
All reviewed patches have been landed. Closing bug.