Revert "Straighten the dead char implementation."

This reverts commit 5ef447ae.

Reverting because this broke a bunch of unit tests -- https://sponge.corp.google.com/target?id=b6439742-099e-46cb-8f00-d0c602a4d9bb&target=com.google.android.inputmethod.latin.tests&searchFor=&show=FAILED&sortBy=STATUS

Change-Id: Ibbd9e11372993f62e630fd9da37158ffcf47c17a