Add FwidthSquircleTestOp::onPrePrepare

This CL also introduces creating the geometryProcessor in the arena (which bypasses the GrProcessor memory pool).

Bug: skia:9455
Change-Id: Ia9d5c0d886ea918d9e4209078a1f7e8595234d0e
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/254963
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
2 files changed