Fix fuzzer bug in SkGradientShader::MakeSweep

In this case, startAngle was NaN while endAngle was -NaN

Change-Id: Ic3498a6f08700437590eb219e2baf535db912cc2
Reviewed-on: https://skia-review.googlesource.com/139980
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
1 file changed