Actually, if you look at the original tests they submitted it was 100% for IE across the board, and if I recall correctly (since they've just replaced the old page) no other browser passed any subset 100%. Clearly they cherry picked the tests, it makes no sense that every test they wrote just happened to pass at that point in time. Either they didn't publish the tests that IE failed, or they intentionally stopped writing new tests some point before they went public to give them time to pass everything fully.

Of course after they published these results it was pointed out that a) the test were wrong and so other browsers were marked as failing, even when they actually passed, and b) IE was getting things wrong but getting marked correct because the tests were wrong. (That's not even touching the fact that they don't even indicate that Firefox and Webkit would pass a whole heap of the tests just by changing a single string in their code to check a different prefix)

They've since scrambled to get their column back up to 100% pass rate and that's why they've updated this page with their new version. Pretty weak all round.