Use GrVertexWriter::writeQuad in ellipse ops

More concise and (hopefully), makes the underlying logic easier to spot.

Bug: skia:
Change-Id: I8dbdcee7c761259dc586311b8c703e87555634cc
Reviewed-on: https://skia-review.googlesource.com/c/172502
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
1 file changed