The following layout test is failing/timing out on debug builds: fast/frames/lots-of-objects.html.
Marked as flaky in debug in <http://trac.webkit.org/r155902>.
It seems like it's currently failing on Apple MountainLion Debug WK1 (Tests) Apple Mavericks Debug WK2 (Tests) Apple Mavericks Release WK2 (Tests) http://webkit-test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=fast%2Fframes%2Flots-of-objects.html
Looks like lots-of-iframes.html is also failing on the exact same set of builders: http://webkit-test-results.appspot.com/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=fast%2Fframes%2Flots-of-iframes.html%2Cfast%2Fframes%2Flots-of-objects.html
Updated the test expectations accordingly in http://trac.webkit.org/changeset/158261.
*** Bug 132256 has been marked as a duplicate of this bug. ***