Cherry-pick 80e4d73. rdar://problem/108683501

    [CSS] Resolve "currentcolor" with style if possible
    https://bugs.webkit.org/show_bug.cgi?id=257255
    rdar://108683501

    Reviewed by Tim Nguyen.

    Ideally, we should never try to resolve "currentcolor" during
    style building.
    However, for the rare cases where we do it (gradient, drop-shadow)
    it's better to use the incomplete style than assuming an absolute color.

    * LayoutTests/fast/css/color-mix-various-expected.html: Added.
    * LayoutTests/fast/css/color-mix-various.html: Added.
    * Source/WebCore/style/ColorFromPrimitiveValue.cpp:
    (WebCore::Style::colorFromPrimitiveValueWithResolvedCurrentColor):
    * Source/WebCore/style/ElementRuleCollector.cpp:
    (WebCore::Style::ElementRuleCollector::addMatchedProperties):

    Canonical link: https://commits.webkit.org/264737@main

Identifier: 259548.795@safari-7615-branch

LayoutTests/fast/css/color-mix-various-expected.html

@@ -0,0 +1,14 @@
+<style>
+body {
+  color: green;
+}
+span {
+  box-shadow: 5px 5px green;
+  text-shadow: 5px 5px green;
+  background: linear-gradient(green, green);
+  filter: drop-shadow(30px 10px 4px green);
+}
+</style>
+
+<span> PASS if no crash and only green</span>
+

LayoutTests/fast/css/color-mix-various.html

@@ -0,0 +1,14 @@
+<style>
+body {
+  color: green;
+}
+span {
+  box-shadow: 5px 5px color-mix(in srgb, green, currentColor);
+  text-shadow: 5px 5px color-mix(in srgb, green, currentColor);
+  background: linear-gradient(green, color-mix(in srgb, green, currentcolor));
+  filter: drop-shadow(30px 10px 4px color-mix(in srgb, green, currentcolor));
+}
+</style>
+
+<span> PASS if no crash and only green</span>
+

Source/WebCore/style/ColorFromPrimitiveValue.cpp

@@ -65,14 +65,14 @@ StyleColor colorFromPrimitiveValue(const Document& document, RenderStyle& style,
 Color colorFromPrimitiveValueWithResolvedCurrentColor(const Document& document, RenderStyle& style, const CSSPrimitiveValue& value)
 {
     // FIXME: 'currentcolor' should be resolved at use time to make it inherit correctly. https://bugs.webkit.org/show_bug.cgi?id=210005
-    if (StyleColor::isCurrentColor(value)) {
+    if (StyleColor::containsCurrentColor(value)) {
         // Color is an inherited property so depending on it effectively makes the property inherited.
         style.setHasExplicitlyInheritedProperties();
         style.setDisallowsFastPathInheritance();
-        return style.color();
     }
 
-    return colorFromPrimitiveValue(document, style, value, ForVisitedLink::No).absoluteColor();
+    auto color = colorFromPrimitiveValue(document, style, value, ForVisitedLink::No);
+    return style.colorResolvingCurrentColor(color);
 }
 
 } // namespace Style