[view-transitions] Register user agent @keyframes rules

https://bugs.webkit.org/show_bug.cgi?id=269504
rdar://123033600

Reviewed by Matthieu Dubet.

Add static storage for user agent @Keyframes, and use it for the viewTransitions.css stylesheet.

This is the same pattern used as `CounterStyleRegistry::userAgentCounterStyles`.

* Source/WebCore/style/StyleResolver.cpp:
(WebCore::Style::Resolver::userAgentKeyframes):
(WebCore::Style::Resolver::addUserAgentKeyframeStyle):
(WebCore::Style::Resolver::isAnimationNameValid):
(WebCore::Style::Resolver::keyframeRulesForName const):
* Source/WebCore/style/StyleResolver.h:
* Source/WebCore/style/UserAgentStyle.cpp:
(WebCore::Style::addUserAgentKeyframes):
(WebCore::Style::UserAgentStyle::ensureDefaultStyleSheetsForElement):

Canonical link: https://commits.webkit.org/274789@main

Source/WebCore/style/StyleResolver.cpp

@@ -216,10 +216,22 @@ void Resolver::appendAuthorStyleSheets(const Vector<RefPtr<CSSStyleSheet>>& styl
         renderView->style().fontCascade().update(&document().fontSelector());
 }
 
+KeyframesRuleMap& Resolver::userAgentKeyframes()
+{
+    static NeverDestroyed<KeyframesRuleMap> keyframes;
+    return keyframes;
+}
+
+void Resolver::addUserAgentKeyframeStyle(Ref<StyleRuleKeyframes>&& rule)
+{
+    const auto& animationName = rule->name();
+    userAgentKeyframes().set(animationName, WTFMove(rule));
+}
+
 // This is a simplified style setting function for keyframe styles
 void Resolver::addKeyframeStyle(Ref<StyleRuleKeyframes>&& rule)
 {
-    auto& animationName = rule->name();
+    const auto& animationName = rule->name();
     m_keyframesRuleMap.set(animationName, WTFMove(rule));
     document().keyframesRuleDidChange(animationName);
 }
@@ -347,7 +359,8 @@ std::unique_ptr<RenderStyle> Resolver::styleForKeyframe(const Element& element,
 
 bool Resolver::isAnimationNameValid(const String& name)
 {
-    return m_keyframesRuleMap.find(AtomString(name)) != m_keyframesRuleMap.end();
+    return m_keyframesRuleMap.find(AtomString(name)) != m_keyframesRuleMap.end()
+        || userAgentKeyframes().find(AtomString(name)) != userAgentKeyframes().end();
 }
 
 Vector<Ref<StyleRuleKeyframe>> Resolver::keyframeRulesForName(const AtomString& animationName) const
@@ -357,9 +370,13 @@ Vector<Ref<StyleRuleKeyframe>> Resolver::keyframeRulesForName(const AtomString&
 
     m_keyframesRuleMap.checkConsistency();
 
+    // Check author map first then check user-agent map.
     auto it = m_keyframesRuleMap.find(animationName);
-    if (it == m_keyframesRuleMap.end())
-        return { };
+    if (it == m_keyframesRuleMap.end()) {
+        it = userAgentKeyframes().find(animationName);
+        if (it == userAgentKeyframes().end())
+            return { };
+    }
 
     auto compositeOperationForKeyframe = [](Ref<StyleRuleKeyframe> keyframe) -> CompositeOperation {
         if (auto compositeOperationCSSValue = keyframe->properties().getPropertyCSSValue(CSSPropertyAnimationComposition)) {

Source/WebCore/style/StyleResolver.h

@@ -81,6 +81,8 @@ struct ResolutionContext {
     bool isSVGUseTreeRoot { false };
 };
 
+using KeyframesRuleMap = HashMap<AtomString, RefPtr<StyleRuleKeyframes>>;
+
 class Resolver : public RefCounted<Resolver>, public CanMakeSingleThreadWeakPtr<Resolver> {
     WTF_MAKE_ISO_ALLOCATED(Resolver);
 public:
@@ -133,6 +135,8 @@ class Resolver : public RefCounted<Resolver>, public CanMakeSingleThreadWeakPtr<
     bool hasViewportDependentMediaQueries() const;
     std::optional<DynamicMediaQueryEvaluationChanges> evaluateDynamicMediaQueries();
 
+    static KeyframesRuleMap& userAgentKeyframes();
+    static void addUserAgentKeyframeStyle(Ref<StyleRuleKeyframes>&&);
     void addKeyframeStyle(Ref<StyleRuleKeyframes>&&);
     Vector<Ref<StyleRuleKeyframe>> keyframeRulesForName(const AtomString&) const;
 
@@ -164,7 +168,6 @@ class Resolver : public RefCounted<Resolver>, public CanMakeSingleThreadWeakPtr<
 
     ScopeRuleSets m_ruleSets;
 
-    typedef HashMap<AtomString, RefPtr<StyleRuleKeyframes>> KeyframesRuleMap;
     KeyframesRuleMap m_keyframesRuleMap;
 
     MQ::MediaQueryEvaluator m_mediaQueryEvaluator;

Source/WebCore/style/UserAgentStyle.cpp

@@ -31,6 +31,7 @@
 
 #include "CSSCounterStyleRegistry.h"
 #include "CSSCounterStyleRule.h"
+#include "CSSKeyframesRule.h"
 #include "CSSValuePool.h"
 #include "Chrome.h"
 #include "ChromeClient.h"
@@ -60,6 +61,7 @@
 #include "RenderTheme.h"
 #include "RuleSetBuilder.h"
 #include "SVGElement.h"
+#include "StyleResolver.h"
 #include "StyleSheetContents.h"
 #include "UserAgentStyleSheets.h"
 #include <wtf/NeverDestroyed.h>
@@ -130,6 +132,15 @@ void static addToCounterStyleRegistry(StyleSheetContents& sheet)
     CSSCounterStyleRegistry::resolveUserAgentReferences();
 }
 
+void static addUserAgentKeyframes(StyleSheetContents& sheet)
+{
+    // This does not handle nested rules.
+    for (auto& rule : sheet.childRules()) {
+        if (auto* styleRuleKeyframes = dynamicDowncast<StyleRuleKeyframes>(rule.get()))
+            Style::Resolver::addUserAgentKeyframeStyle(*styleRuleKeyframes);
+    }
+}
+
 void UserAgentStyle::addToDefaultStyle(StyleSheetContents& sheet)
 {
     RuleSetBuilder screenBuilder(*defaultStyle, screenEval());
@@ -276,6 +287,7 @@ void UserAgentStyle::ensureDefaultStyleSheetsForElement(const Element& element)
     if (!viewTransitionsStyleSheet && element.document().settings().viewTransitionsEnabled()) {
         viewTransitionsStyleSheet = parseUASheet(StringImpl::createWithoutCopying(viewTransitionsUserAgentStyleSheet, sizeof(viewTransitionsUserAgentStyleSheet)));
         addToDefaultStyle(*viewTransitionsStyleSheet);
+        addUserAgentKeyframes(*viewTransitionsStyleSheet);
     }
 
     ASSERT(defaultStyle->features().idsInRules.isEmpty());