Visiting the page given in the URL above (found at "Test runner online" at www.jsunit.net) and clicking the "Run" button gives one failure at server/jsUnitServerAjaxTests.html, testReceiveServerStatus failed. The explanation is "Expected <server started|test run requested> (String) but was <null>. I do not know JavaScript processing enough to say, whether this is a bug in the test (ok in Firefox 3b5 anyway) or in Webkit. The test was run with Webkit r33029.
Confirming as a regression from Safari 3.1.1. It is not immediately clear what has changed though, a reduction will need to be made.
Not knowing what has been done to correct this bug I noticed that at least in version r34278 (WinXP) this works ok.
THis fails in revisions up to r33980, but passes in r33944-sf and r34020, which means that switching JavaScript interpreter to SquirrelFish magically fixed this.