to help avoid confusion between several different layers that are all related to "root". This particular isRootLayer flag is only set by NonCompositedContentHost and actually refers to the non-composited content layer.
Created attachment 107598 [details] Patch
Comment on attachment 107598 [details] Patch Clearing flags on attachment: 107598 Committed r95348: <http://trac.webkit.org/changeset/95348>
All reviewed patches have been landed. Closing bug.