Fix GrPathUtils::convertLineToCubic

Change-Id: Ie096c9f0629102c5c6b2ca9ddfb8e5e2c31218f7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/333145
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
2 files changed