Stop uselessly remembering a value (A2)

The value is only used in debug mode, and it can be recomputed
at the time.
This change does not impact the logic. There is however a side
effect: in debug mode, the normalized score will be displayed
also when the word comes out of the whitelist or is a valid word.
It's actually a good thing.

The end purpose is to make all methods in AutoCorrection static.

Change-Id: I1642b1fdfa6ae62b8aa2fed94a8a26ff4a7e4d0e