Minimal change to ensure that position is last saved when docking.

- When a task is docked from Recents, the last position is never updated
  if the user never touches the divider.  Ensure that the default dock
  snap target is saved in this case as well.

Bug: 66903645
Test: Dock a task from Recents, go home, and hit recents
Change-Id: Ia229d2ba0eee792424fb9e9c043320cec71695dc