Scroll to text fragment highlight style can create unreadable text, especially in dark mode

[hortont424]

32caf7b

Scroll to text fragment highlight style can create unreadable text, especially in dark mode
https://bugs.webkit.org/show_bug.cgi?id=272583
rdar://126539910

Reviewed by Abrar Rahman Protyasha.

Scroll-to-Text-Fragment highlights (and App Highlights) dramatically change
the surrounding color of the highlighted text. In many cases, this is fine, but
on dark pages with light or mid-tone text, the default highlight background
color (yellow) makes it hard to read the text.

Align ourselves with Chrome's behavior: pick a contrasting color, but only
if using the default highlight color; if the author uses ::target-text to style
the background, we leave it alone, assuming they knew what they were doing.

Test: http/tests/scroll-to-text-fragment/highlighted-text-contrast.html,
      http/tests/scroll-to-text-fragment/highlighted-text-contrast-targettext.html

* LayoutTests/http/tests/scroll-to-text-fragment/highlighted-text-contrast-expected.html: Added.
* LayoutTests/http/tests/scroll-to-text-fragment/highlighted-text-contrast.html: Added.
Add a test that ensures that we contrastify highlighted text colors.

* LayoutTests/http/tests/scroll-to-text-fragment/highlighted-text-contrast-targettext-expected-mismatch.html: Added.
* LayoutTests/http/tests/scroll-to-text-fragment/highlighted-text-contrast-targettext.html: Added.
Add a test that ensures that we do NOT contrastify text colors when the author overrides the default style.

* Source/WebCore/rendering/RenderReplaced.cpp:
(WebCore::RenderReplaced::calculateHighlightColor const):
* Source/WebCore/rendering/RenderTheme.cpp:
(WebCore::RenderTheme::annotationHighlightBackgroundColor const):
(WebCore::RenderTheme::platformAnnotationHighlightBackgroundColor const):
Rename annotationHighlightColor to annotationHighlightBackgroundColor, to allow
space for our "Foreground" variant.

(WebCore::RenderTheme::annotationHighlightForegroundColor const):
Add annotationHighlightForegroundColor, which is computed by using the CSS
contrast-color() algorithm on the background color.

(WebCore::RenderTheme::annotationHighlightColor const): Deleted.
(WebCore::RenderTheme::platformAnnotationHighlightColor const): Deleted.
* Source/WebCore/rendering/RenderTheme.h:
* Source/WebCore/rendering/StyledMarkedText.cpp:
(WebCore::resolveStyleForMarkedText):
Adopt annotationHighlightForegroundColor for STTF and app highlights, only if ::target-text is not used.

Canonical link: https://commits.webkit.org/301930@main

9166da1

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	🛠 watch
	✅ 🛠 watch-sim

[webkit-early-warning-system]

EWS run on previous version of this PR (hash ade6616)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	⏳ 🧪 ios-wk2	🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	⏳ 🧪 ios-wk2-wpt	⏳ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	⏳ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	🧪 api-gtk
	✅ 🧪 vision-wk2	⏳ 🧪 mac-intel-wk2	🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	🛠 tv-sim
	🛠 watch
	🛠 watch-sim

[webkit-early-warning-system]

EWS run on current version of this PR (hash 9166da1)

Misc	iOS, visionOS, tvOS & watchOS	macOS	Linux	Windows	Apple Internal
✅ 🧪 style	✅ 🛠 ios	✅ 🛠 mac	✅ 🛠 wpe	🛠 win	✅ 🛠 ios-apple
✅ 🧪 bindings	✅ 🛠 ios-sim	✅ 🛠 mac-AS-debug	✅ 🧪 wpe-wk2	🧪 win-tests	✅ 🛠 mac-apple
✅ 🧪 webkitperl	✅ 🧪 ios-wk2	✅ 🧪 api-mac	✅ 🧪 api-wpe		✅ 🛠 vision-apple
	🧪 ios-wk2-wpt	✅ 🧪 mac-wk1	✅ 🛠 wpe-cairo
	✅ 🧪 api-ios	✅ 🧪 mac-wk2	✅ 🛠 gtk
	✅ 🛠 vision	🧪 mac-AS-debug-wk2	✅ 🧪 gtk-wk2
	✅ 🛠 vision-sim	✅ 🧪 mac-wk2-stress	✅ 🧪 api-gtk
✅ 🛠 🧪 merge	✅ 🧪 vision-wk2	🧪 mac-intel-wk2	✅ 🛠 playstation
	✅ 🛠 tv	✅ 🛠 mac-safer-cpp
	✅ 🛠 tv-sim
	🛠 watch
	✅ 🛠 watch-sim

[webkit-commit-queue]

Committed 301930@main (32caf7b): https://commits.webkit.org/301930@main

Reviewed commits have been landed. Closing PR #52779 and removing active labels.