switch to double in conic split on infinities

If the input conic doesn't contain infinities, it should be possible
to compute the split conic without infinities as well. Fix the case
fuzzer exposes.

R=reed@google.com,fmalita@chromium.org
Bug: skia:7435
Change-Id: Ic128fa14ea0622188e5c43efc16b684efa342e9e
Reviewed-on: https://skia-review.googlesource.com/102425
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
2 files changed