* ImplFillSwappedGraphicObject method is part of
the old caching mechanism which interferes with
the newer one, so remove this method.
* Use Graphic size directly becuase in some case
it does not match with the GraphicObject's
size.
* Assertions to avoid underflow of mnUsedSize

Change-Id: I3381f49ca05e3e5d565848c8af24c78e7b9ac3af