Restore 'medPrecision' label in ellipse effect FP.

This was removed in http://review.skia.org/377842 to allow compilation
without control-flow analysis. We now support const bools in @if
statements (as of http://review.skia.org/379063) and can relax this
restriction a bit.

Change-Id: If3e8018c599d765075568a90af94fb4e4cb25118
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/379797
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
3 files changed