Merge "Fix elliptical rrect clip shaders for large radii on devices with mediump" into master-skia

https://skia.googlesource.com/skia/+/c41f4d60559b0891353f8028d521b52e7a36d5da

Change-Id: If8bd23caa759ff9eea920b88f811b4cb0bc7c39e