Revert "Revert "Add arcs as a specialized geometry to GrShape.""

This reverts commit af88ec37124846a0168a4ab061bf10cc6030c2d6.

Bug: skia:7794
Change-Id: I2d0e1d7b4e025481241d823b09f5de5d0f1a13eb
Reviewed-on: https://skia-review.googlesource.com/123627
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
7 files changed