We'll need this for copy-on-write when style sheet data is shared between documents.
Created attachment 138633 [details] patch
Comment on attachment 138633 [details] patch Looks legit.
Comment on attachment 138633 [details] patch Attachment 138633 [details] did not pass mac-ews (mac): Output: http://queues.webkit.org/results/12525331
Comment on attachment 138633 [details] patch Attachment 138633 [details] did not pass qt-wk2-ews (qt): Output: http://queues.webkit.org/results/12490342
http://trac.webkit.org/changeset/115115 Build fix: http://trac.webkit.org/changeset/115117
Another build fix: http://trac.webkit.org/changeset/115120