Early-out in Region::unite() for adding an empty region.
Created attachment 128099 [details] Patch We've noticed that unite() with an empty region ends up making a copy of the entire current Region, and may also add an empty rect in the return from rects(). This early out saves a lot of work for this case, and fixes Region uniqueness for the given area it covers.
Comment on attachment 128099 [details] Patch Clearing flags on attachment: 128099 Committed r108433: <http://trac.webkit.org/changeset/108433>
All reviewed patches have been landed. Closing bug.