Two fo the layout tests, dom/html/level2/events/dispatchEvent11 and dom/html/level2/events/ dispatchEvent13, are adding an event listener object, but then removing the event listener's "handleEvent" function instead of the object. That's incorrect, and that's why they're failing.
Created attachment 3436 [details] patch to correct the tests I presume Curt will also want to correct the originals somehow.
I beat you, see bug 4491.
*** This bug has been marked as a duplicate of 4491 ***