The test is failing intermittently on Webkit Linux 32, Webkit Mac10.7 and Webkit Win chromium bots. Here is the link to flakiness dashboard: http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=perf%2Fshow-hide-table-rows.html From the graphs it looks like the flakiness was introduced in trac.webkit.org/changeset/130337