Fixing some drag and drop issues.

- When opening recents while there is a task docked, initialize the
  stack scroll to the front of the stack
- When undocking a task while recents is open, scroll to the front of
  the stack
- Fixing offset when adjusting the task stack size due to top inset 
  being double applied in some dock states
- Fixing issue with task view not scaling when picking up from the 
  freeform workspace

Change-Id: I15436ac21f05ff521492d8ae1c682a414503101a