Improve precision and speed of oval rendering.

Reduces computations, and fixes some issues with large ovals.

Change-Id: I2a961f2115e4e5fcb756714dd7e45c7528ed679a
Reviewed-on: https://skia-review.googlesource.com/136229
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Jim Van Verth <jvanverth@google.com>
1 file changed