Add tolerance to quadratic and linear cubic detection
Add tolerance to quadratic and linear cubic detection

Otherwise these can be misclassified as cusps since there is already
tolerance in the discriminant test.

BUG=skia:

Change-Id: Id02c12f671714cebf799953ebed5335ee4c4d52a
Reviewed-on: https://skia-review.googlesource.com/9355
Reviewed-by: Cary Clark <52792aa984ff6c4e9c802c7fa3093ed6a52a791f@google.com>
Commit-Queue: Chris Dalton <ef7fc3a08ada7d31f16e9a18b5f3c728256e041e@google.com>

aosp-mirror/platform_external_skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,google/skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,HalCanary/skia-hc,rubenvb/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,google/skia,google/skia,rubenvb/skia,HalCanary/skia-hc,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,rubenvb/skia,rubenvb/skia,google/skia,HalCanary/skia-hc,google/skia,google/skia,google/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia,Hikari-no-Tenshi/android_external_skia