Wide color gamut support and working example.

Fixes release-cpu build issue, un-revert cl 289733

Color space arguments accepted at surface creation, paint, gradient, and other call sites.
Works correctly only when chrome happens to be rendering itself in the same color space
the canvaskit user has chosen, there's not yet end to end color management of
canvases supported in browsers.

readPixels not yet working due to possible chrome bug.

Reviewed-on: https://skia-review.googlesource.com/c/skia/+/289733
Commit-Queue: Nathaniel Nifong <nifong@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Change-Id: I65ce1c643dac57e14b8476f598c96b12b7e040ce
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/291896
10 files changed