I simplified the determining of the next region part of updateShapeAndSegmentsForCurrentLineInFlowThread's implementation in order to make the code more straightforward. I also tried to avoid using regionAtBlockOffset(...) function as possible, since it's always that reliable, what I'll will report in a separate bug.
Created attachment 214974 [details] Patch
Comment on attachment 214974 [details] Patch r=me
Comment on attachment 214974 [details] Patch Clearing flags on attachment: 214974 Committed r158016: <http://trac.webkit.org/changeset/158016>
All reviewed patches have been landed. Closing bug.