Refactoring all coordinate-switching functionality to use a single "mode" flag
as opposed to having a bunch of boolean values. This enables the same set of
options across the board, and a consistent interface. This was previously
done for mapLocalToContainer.
The imptetus for this for this stems from the one logical change in this patch
which only effects sub-pixel layout. FrameView::convertToRenderer and
convertFromRenderer return IntPoint coordinates, and need to also snap transform
offsets to determine proper rects for scrolling.
Unlabeled functions below are simply being updated to these new interfaces.