Add more condition to avoid recomputations for async text

Add more condition to avoid recomputations for async text

Do not request async render if only the size has changed when manual render is completed.
Users may attempt to change the size inside the completed callback post manual render.
In case of ASYNC_AUTO, this could potentially trigger relayout and engender further computation.
This is needed to avoid recomputations, but it may have some limitations.

Change-Id: I6a54b6c47866f65faaa38ba4280b4f4ced4c637e
Signed-off-by: Bowon Ryu <bowon.ryu@samsung.com>