Add support for using 'currentcolor' with color-mix()
Pull request: https://github.com/WebKit/WebKit/pull/8529
<rdar://problem/104133292>
Committed 258970@main (f99a53e73e51): <https://commits.webkit.org/258970@main> Reviewed commits have been landed. Closing PR #8529 and removing active labels.
Re-opening for pull request https://github.com/WebKit/WebKit/pull/8852
Committed 259145@main (88a0736c2c2d): <https://commits.webkit.org/259145@main> Reviewed commits have been landed. Closing PR #8852 and removing active labels.