Add experimental feature flag for CSS Typed OM Color support. The color API in CSS Typed OM is still changing a lot and Blink hasn't shipped this part yet.
Pull request: https://github.com/WebKit/WebKit/pull/6886
Committed 257172@main (dc6ec366afda): <https://commits.webkit.org/257172@main> Reviewed commits have been landed. Closing PR #6886 and removing active labels.
<rdar://problem/102801297>