The tile stitch variables are used (and overwritten) by all threads in the same time.
Created attachment 121996 [details]
Comment on attachment 121996 [details]
Ah thanks a lot for finding that annoying bug! You should mention in the ChangeLog that this fixes the problems with svg/dynamic-updates/SVGFETurb* and update the pixel test results.. still, r=me.
Landed in: http://trac.webkit.org/changeset/104824