Some apps depend on the keyboard sending something to them
when the text is empty. This is BROKEN. Your app must not lie
to the keyboard about what is before the cursor. If there is something
to delete, you must not pretend there is not and try to catch some
delete event. This will result in a bad user experience. This will not
work with all IMEs. If your app needs this broken behavior, you're
doing it wrong. Seriously guys, we're not in the era of typewriters
any more, there are touch screens, there are gestures, there is
accessibility, there are many innovative IMEs that don't have
keys. Do *NOT* rely on key events.

This change implements an ugly hack so that these broken apps
may continue half-working with LatinIME. We are very unhappy
about this.

Bug: 12998568
Change-Id: Ia62ae2fbee4fee65b463acf3a79aafcfd0defa1d