Avoid GrEllipseEffect for small radii on devices without 32 bit float.

Also limit small radius bail in GrCircleEffect to clip out cases.

Change-Id: I14ce736969b05203219d68f30283c36c84f78f3a
Reviewed-on: https://skia-review.googlesource.com/80621
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
17 files changed