UAIG Menu events

We are going to get UAIG published but we need the menu mappings to be
correct for MSAA. They are not:

http://www.w3.org/WAI/PF/aria-implementation/#mapping_events_menus

1. Row 1: We ONLY get an EVENT_MENU_START if we first focus a menu item in
the menu bar. The current test suite fires a EVENT_SYSTEM_MENUPOPUPSTART
when you open the sub menu as it is a pop-up menu. IOW you have to go to
the menubar first to get a EVENT_MENU_START event which starts the menu
start sequence.  Menu mode should include popping up a menu.
2. Row 3: When a popup menu is made visible (we have this in the tests
cases). We do not get an EVENT_SYSTEM_MENUSTART. We only get a
EVENT_SYSTEM_MENUPOPUPSTART. Additionally, just showing a pop up menu is
all that is required to get: EVENT_SYSTEM_MENUPOPUPSTART. You don't need to
set focus on it.
3. Row 5: If you simply show and hide a popup menu I am not seeing a
EVENT_SYSTEM_MENUEND
4. Row 6: I am not seeing a EVENT_SYSTEM_MENUEND in Firefox for a popup
menu leaving