Comment 20 for bug 1404715

It is also possible to round intersections to their nearest integer,
it is a little more elaborate:

it is necessary to

properly round the integer quotient to the nearest integer,
change the cairo_bo_intersect_ordinate 'exactness' member to hold
say {EXCESS, EXACT, DEFECT } values, and split INTERSECTION events
in INTERSECTION_ABOVE and INTERSECTION_BELOW events which should
be processed

INTERSECTION_ABOVE < STOP < START < INTERSECTION_ABOVE

with that approach few image tests that fail with the patch
above do pass.