we go to compute xMin, yMin, xMax, and yMax for the pixels, we no longer need
the assistance of Math.min() and Math.max(), in other words we no longer use
m_clipXMin, m_clipYMin, m_clipXMax, and m_clipYMax as boundaries. This is a
rather delicate change but theoretically everything should work. Some simple
tests show that things still work the way they're supposed to. Unfortunately
I don't have extensive regression tests at the moment.
