[canvaskit] Add tests for gradients
[canvaskit] Add tests for gradients

Change-Id: I28a001f281d9dc0c64c37ad1f22a6387eadca843
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/277607
Reviewed-by: Nathaniel Nifong <1ce561679465ea4956c6210637580cd7ba456816@google.com>

aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia,google/skia,aosp-mirror/platform_external_skia,google/skia,google/skia,google/skia,aosp-mirror/platform_external_skia