[NUI][ACR-319][Add Position, Size two parameter constructor TCs]

[NUI][ACR-319][Add Position, Size two parameter constructor TCs]

- This doesn't violate API break so it originally doesn't need ACR.
- However, API team requested ACR to maintain the history and manage API.
- Size and Position have already been public-released, so if exception is added the behavior will be changed also.
  This could make unexpected exception from VD application side and could make some user complain.
- I strongly recommand not to change the behavior for public-released API, so I don't want to change them.
  I politely request for you to consider current situation.

Change-Id: I9a8b156eb5109ff023456a7f30b67c27af8413f0