We will be refactoring these into Sputnik and test262 tests. But the results below are immediately useful and seem correct, so here they are for now in an unpolished form. These tests assume a browser that's on its way to being ES5 compliant, as it uses some ES5 APIs to drive the tests.
It should work at least starting with Chrome 9, Safari 5, FireFox 3.6, IE 9, and Opera 11. I haven't tried it on earlier or other browsers.