Support all non-absolute colors as a basis for relative color syntax
This is simply a matter of lifting the restriction in the parsing code.
Existing recursive behaviors in CSSColorFunctionParser and
StyleColor::UnresolvedColorFunction are already set up to handle cases
beyond just currentcolor as an origin.
Bug: 325309578, 41492196
Change-Id: I5ce01dc6eb7757955583c7ae4a606a3306478dca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5757594
Reviewed-by: Fredrik Söderquist fs@opera.com
Commit-Queue: Kevin Babbitt kbabbitt@microsoft.com
Cr-Commit-Position: refs/heads/main@{#1353402}