Optimized size negotiation
1. Remove size negotiation from scrollable things as they are not layout containers (yes, ItemView does not do size negotiations)
2. Make size negotiation containers members of relayout controller so we avoid hundreds of memory allocations per frame
3. Reduce the overhead of size negotiation request by having a static flag instead of hundreds of handle creations and dynamic casts etc
Change-Id: I9f11a45a70b262c0c6a07358350a8203c21fc2ce
Signed-off-by: Adeel Kazmi <adeel.kazmi@samsung.com>