Fix sampling location for dashed circle in p3_ovals

I was sampling near the edge of the stroke, not the middle of it,
so some configs were picking up antialiased pixels.

Bug: skia:
Change-Id: I46314ba0bafe056505037deaa8dd32f4f68119f6
Reviewed-on: https://skia-review.googlesource.com/c/172503
Auto-Submit: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed