The fast/css/text-overflow-ellipsis-behind-floats.html reftest is failing since introduced in r150602 http://trac.webkit.org/changeset/150602 http://webkit-test-results.appspot.com/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=fast%2Fcss%2Ftext-overflow-ellipsis-behind-floats.html The failure is minimal, various letters like p and q getting their bottom cut off in the reference file.
Fixed in r222086.