Restart suggestions when backspacing into a reverted word.

This is required for the final corrected word to be learned,
as learning only occurs when suggestions are active.

Note: This is already happening when backspacing into a non-reverted
word

Bug: 19619907
Bug: 18465402
Change-Id: I99a1d4f0ca0d62a2cdfa24cc0833ce89391715d9