Enable choosing a bigram prediction several times in a row.

This change fixes a bug that prevented to choose a prediction
several times in a row because the predictions would be replaced
right away by punctuations.
Please note several things about this change:
- Recorrection is pretty much in the middle of being refactored.
  This change has no effect on recorrection itself, but may make
  existing strange behavior more obvious when moving the cursor
  for example.
- The part of this change in Recorrection.java is not used in
  master at the moment because ongoing changes on recorrection
  result in the control never landing there, but would have been
  needed in the past and may be needed in the future.
- This change may have adverse effects on performance which need
  to be evaluated. A comment in the code has also been written
  to this effect.
- This does not fix bug 4466199, only addresses a pinpoint case
  of it to help evaluating the bigram predictions feature.

Bug: 4466199
Change-Id: I7219e5aeb74dff9251d12b2a72f94448dbb3e63f