R=reed@google.com BUG=skia:959 GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1562333002 Review URL: https://codereview.chromium.org/1562333002
BUG=None TEST=make tests && out/Debug/tests -m Interpolator R=mtklein@google.com, bsalomon@google.com Author: tfarina@chromium.org Review URL: https://codereview.chromium.org/351713005