Fix conical test where r1 = r2 = 0

Bug: skia:7436
Change-Id: I0fdbd458d4e2da53e587be27ac90fbb2d32584e5
Reviewed-on: https://skia-review.googlesource.com/89520
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Yuqian Li <liyuqian@google.com>
1 file changed