This uses quad approximations of the outer and inner paths describing a stroke. Cubic...

This uses quad approximations of the outer and inner paths describing a stroke. Cubics and conics' thick strokes are approximated with quads as well.

The approximation uses a similar error term as the fill scan converter to determine the number of quads to use.

This also updates SampleApp QuadStroker test with conics, ovals, and stroked text.

Review URL: https://codereview.chromium.org/932113002