Before r135750 the line layout algorithm was also detecting lines invalidated by regions changing width. The case of a region changing width should be handled by the blocks by setting the relayoutChildren flag and thus invalidating the lines.
Created attachment 177734 [details] Patch
Comment on attachment 177734 [details] Patch r=me
Comment on attachment 177734 [details] Patch Clearing flags on attachment: 177734 Committed r136793: <http://trac.webkit.org/changeset/136793>
All reviewed patches have been landed. Closing bug.
*** Bug 103680 has been marked as a duplicate of this bug. ***