Previously, we couldn't actually unbind some event handlers. The
problem was that when a user called $.off(events, handler), the
passed handler wouldn't match any that were actually bound because
the handler that was actually bound was our wrapper.
This bug specifically caused the handlers for our idle timers to
never be unbound, effectively never cancelling them.
(imported from commit 48efac954994a05c356d326e64a78ab0ace9fe3e)