It seems unlikely that this can be made deterministic by saving/restoring initial main frame size. Instead we can just memoize the attribute values as script accesses them.
Created attachment 228902 [details]
Comment on attachment 228902 [details]
Clearing flags on attachment: 228902
Committed r166984: <http://trac.webkit.org/changeset/166984>
All reviewed patches have been landed. Closing bug.