Fix floating toolbar popping frequently after Replace/Copy

Invalidate the LAST_CUT_OR_COPY_TIME when text changes. Reflect
this in the variable names. Fixes the selection mode without
selection (PASTE|SELECT_ALL) toggling when changing text in the
15 sec window this mode has to show.

Bug: 20440790
Change-Id: Ie7ea55916e1633ed4981654c6d80168b1247bc35
2 files changed