Increase accuracy of expected values in color-computed-relative-color.html
The tests in the modified section looks like it uses values that are
slightly inaccurate, failing tests on Firefox. It looks like they were
created with results from another browser, so I've changed the values
to be closer to reference values from colorjs.io.
This might fails tests in other browsers, but now the expected values
at least are more accurate.
Differential Revision: https://phabricator.services.mozilla.com/D211033
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1897975
gecko-commit: 4ca581a76a5912cc11aba86f17d038717dcce467
gecko-reviewers: layout-reviewers, emilio