http://test-results.appspot.com/dashboards/flakiness_dashboard.html#showAllRuns=true&showExpectations=true&tests=tables%2Fmozilla%2Fmarvin%2Fbackgr_index.html%20tables%2Fmozilla_expected_failures%2Fmarvin%2Fbackgr_border-table-cell.html
Removed the 2 entries from TestExpectations in http://trac.webkit.org/changeset/130969. According to the flakiness dashboard, they hadn't failed for 100 runs. Not sure why they were flaky a week ago but it's pretty obvious on the flakiness dashboard that it just stopped.