The change in [1] is likely responsible for a regression in which we're
not taking into account P2 for gradient skewing anymore.
Fix that, and add a test case to the gradient set of test cases.
Source for test glyph, see here:
https://github.com/googlefonts/color-fonts/pull/90/files
[1] 2da029b28f
Cq-Include-Trybots: luci.skia.skia.primary:Test-Android-Clang-GalaxyS20-GPU-MaliG77-arm64-Release-All-Android_NativeFonts,Test-Debian10-Clang-GCE-CPU-AVX2-x86_64-Debug-All-NativeFonts
Bug: skia:12822, chromium:1287162
Change-Id: I8b790e2a5c6c04487118306b4b38b1d77349431d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/494676
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Dominik Röttsches <drott@google.com>
6dece64b9d