MouseEvent.layer empty in older browsers

Whenever I receive mouse events from markers and objects the derive from L.Path, e.layer is empty.  Instead I have to use e.target.  This used to work just fine with 0.5.1,  but is broken as of at least 0.6.3 (possibly earlier).  It's doubly strange in that it's only affecting older browsers -- FF22 reports the event using e.layer.
