Fix some task view fling calculations

- Map to progress 1 instead of dividing by 0 if expectedDuration == 0
- Map to starting progress one frame ahead based on velocity
- Change direction of velocity so it's in the same direction as the
  task progress (0 is down and 1 is up).

Change-Id: I5ac3f8a0d6c616bd303ac1a902242964bb33d3c7