Make ShadowRRectOp a non-legacy GrMeshDrawOp

This also removes the ability to have an arbitrary GrPaint with this op and as a consequence simplifies the op and its GrGeometryProcessor.

Change-Id: I19cc1c6f73a47e8925fc826291aad42e9423164d
Reviewed-on: https://skia-review.googlesource.com/22380
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Jim Van Verth <jvanverth@google.com>
9 files changed