Invalidate 'fill'/'stroke' color expressions on currentcolor changes

For the 'fill' and 'stroke' properties, changes to currentcolor wasn't
picked up if the <color> value was a function.

Add checks for said properties within the diff-field-flag block that
responds to changes in currentcolor. Rename the invalidation flag to
"color-parameter" instead of "background-current-color" since it's
applies to more properties than just 'background-{color,image}".

A test for this case already existed, but since it wasn't guaranteed to
have triggered paint before changing the style it would flakily pass
(most of the time). Add an additional rAF cycle to ensure paint has
occurred.

Fixed: 400828292
Change-Id: I2113162d58044df7027e48c7d59d3aa403142f17
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6333535
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/main@{#1429467}