Fix some bugs with MenuPopupHelper and ListPopupWindow

Clean up handling of a few conditions in MenuPopupHelper that the
monkeys manage to trigger around the use of ViewTreeObserver. (bug
3443819, bug 3312949)

Fix a bug where a stale handler message could cause a ListPopupWindow
to reopen itself after being dismissed. (bug 3453607)

Change-Id: I488014767ccee785500862a2572beb35901d173b