Allow Latin IME to cancel smiley-auto-correct consistenly

This change makes Latin IME behave consistently with regards
to other auto-correction cancellations in cases of auto-correction
cancellation after smiley-triggered auto-correction. That is,
pressing the smiley key when the keyboard signals it's about to
auto-correct will get the auto-correction there plus a smiley,
and pressing backspace will cancel the auto-correction, and
pressing backspace again will delete the smiley.

Bug: 7067593
Change-Id: Ia7eef70a5d06b8b9afa1f1fbb0ed1dbc21a3059f