Instead of CSSColorValue holding a Gfx::Color, make it an abstract class
with subclasses for each different color function, to match the Typed-OM
spec. This means moving the color calculations from the parsing code to
the `to_color()` method on the style value.
This lets us have calc() inside a color function, instead of having to
fully resolve the color at parse time. The canvas fillStyle tests have
been updated to reflect this.
The other test change is Screenshot/css-color-functions.html: previously
we produced slightly different colors for an alpha of 0.5 and one of
50%, and this incorrect behavior was baked into the test. So now it's
more correct. :^)
(cherry picked from commit 3af6a69f1e13803c64466a9b24b7bd7d75d459df;
amended to:
* resolve a minor conflict in Parser.cpp due to upstream not having
https://github.com/LadybirdBrowser/ladybird/pull/385#issuecomment-2227130015
* rebaseline canvas-fillstyle-rgb.png since the diff didn't apply due to
us not having https://github.com/LadybirdBrowser/ladybird/pull/999
* remove css-color-functions-ref.png and instead update
css-color-functions-ref.html since that file is still a reftest due to us
not having https://github.com/LadybirdBrowser/ladybird/pull/736
Makes it much easier to see what actually changed.
)
b65ccb4dc6