LibWeb/CSS: Use CSSRule's context to parse new child rules

Keep track of which CSSRule owns a CSSRuleList, and then use that to
produce a stack of RuleContexts for the CSS Parser to use.

There are certainly other places we should do this!

Libraries/LibWeb/CSS/CSSGroupingRule.cpp

@@ -18,6 +18,7 @@ CSSGroupingRule::CSSGroupingRule(JS::Realm& realm, CSSRuleList& rules, Type type
     : CSSRule(realm, type)
     , m_rules(rules)
 {
+    m_rules->set_owner_rule(*this);
     for (auto& rule : *m_rules)
         rule->set_parent_rule(this);
 }

Libraries/LibWeb/CSS/CSSRuleList.cpp

@@ -46,6 +46,7 @@ void CSSRuleList::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);
     visitor.visit(m_rules);
+    visitor.visit(m_owner_rule);
 }
 
 // https://drafts.csswg.org/cssom/#insert-a-css-rule
@@ -62,11 +63,12 @@ WebIDL::ExceptionOr<unsigned> CSSRuleList::insert_a_css_rule(Variant<StringView,
     // NOTE: The insert-a-css-rule spec expects `rule` to be a string, but the CSSStyleSheet.insertRule()
     //       spec calls this algorithm with an already-parsed CSSRule. So, we use a Variant and skip step 3
     //       if that variant holds a CSSRule already.
+    Parser::ParsingParams parsing_params { realm() };
+    parsing_params.rule_context = rule_context();
+
     CSSRule* new_rule = nullptr;
     if (rule.has<StringView>()) {
-        new_rule = parse_css_rule(
-            Parser::ParsingParams { realm() },
-            rule.get<StringView>());
+        new_rule = parse_css_rule(parsing_params, rule.get<StringView>());
     } else {
         new_rule = rule.get<CSSRule*>();
     }
@@ -74,7 +76,7 @@ WebIDL::ExceptionOr<unsigned> CSSRuleList::insert_a_css_rule(Variant<StringView,
     // 4. If new rule is a syntax error, and nested is set, perform the following substeps:
     if (!new_rule && nested == Nested::Yes) {
         // - Set declarations to the results of performing parse a CSS declaration block, on argument rule.
-        auto declarations = parse_css_property_declaration_block(Parser::ParsingParams { realm() }, rule.get<StringView>());
+        auto declarations = parse_css_property_declaration_block(parsing_params, rule.get<StringView>());
 
         // - If declarations is empty, throw a SyntaxError exception.
         if (declarations.custom_properties.is_empty() && declarations.properties.is_empty())
@@ -225,4 +227,13 @@ Optional<JS::Value> CSSRuleList::item_value(size_t index) const
     return {};
 }
 
+Vector<Parser::RuleContext> CSSRuleList::rule_context() const
+{
+    Vector<Parser::RuleContext> context;
+    for (auto* rule = m_owner_rule.ptr(); rule; rule = rule->parent_rule())
+        context.append(Parser::rule_context_type_for_rule(rule->type()));
+    context.reverse();
+    return context;
+}
+
 }

Libraries/LibWeb/CSS/CSSRuleList.h

@@ -11,6 +11,7 @@
 #include <AK/Function.h>
 #include <LibWeb/Bindings/PlatformObject.h>
 #include <LibWeb/CSS/CSSRule.h>
+#include <LibWeb/CSS/Parser/RuleContext.h>
 #include <LibWeb/Forward.h>
 #include <LibWeb/TraversalOrder.h>
 #include <LibWeb/WebIDL/ExceptionOr.h>
@@ -62,6 +63,7 @@ public:
     // Returns whether the match state of any media queries changed after evaluation.
     bool evaluate_media_queries(HTML::Window const&);
 
+    void set_owner_rule(GC::Ref<CSSRule> owner_rule) { m_owner_rule = owner_rule; }
     void set_rules(Badge<CSSStyleSheet>, Vector<GC::Ref<CSSRule>> rules) { m_rules = move(rules); }
 
     Function<void()> on_change;
@@ -72,7 +74,10 @@ private:
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;
 
+    Vector<Parser::RuleContext> rule_context() const;
+
     Vector<GC::Ref<CSSRule>> m_rules;
+    GC::Ptr<CSSRule> m_owner_rule;
 };
 
 }

Libraries/LibWeb/CSS/CSSStyleProperties.cpp

@@ -1216,6 +1216,8 @@ void CSSStyleProperties::set_declarations_from_text(StringView css_text)
     auto parsing_params = owner_node().has_value()
         ? Parser::ParsingParams(owner_node()->element().document())
         : Parser::ParsingParams();
+    parsing_params.rule_context.append(Parser::RuleContext::Style);
+
     auto style = parse_css_property_declaration_block(parsing_params, css_text);
     set_the_declarations(style.properties, style.custom_properties);
 }

Libraries/LibWeb/CSS/Parser/Parser.cpp

@@ -1360,9 +1360,7 @@ Parser::PropertiesAndCustomProperties Parser::parse_as_property_declaration_bloc
     };
 
     // 1. Let declarations be the returned declarations from invoking parse a block’s contents with string.
-    m_rule_context.append(RuleContext::Style);
     auto declarations_and_at_rules = parse_a_blocks_contents(m_token_stream);
-    m_rule_context.take_last();
 
     // 2. Let parsed declarations be a new empty list.
     PropertiesAndCustomProperties parsed_declarations;

Tests/LibWeb/Text/expected/wpt-import/css/css-conditional/js/conditional-CSSGroupingRule.txt

@@ -2,14 +2,14 @@ Harness status: OK
 
 Found 34 tests
 
-26 Pass
-8 Fail
+30 Pass
+4 Fail
 Pass	@media is CSSGroupingRule
 Pass	@media rule type
 Pass	Empty @media rule length
 Fail	insertRule of @import into @media
-Fail	insertRule into empty @media at bad index
-Fail	insertRule into @media updates length
+Pass	insertRule into empty @media at bad index
+Pass	insertRule into @media updates length
 Pass	insertRule of valid @media into @media
 Pass	insertRule of valid style rule into @media
 Fail	insertRule of invalid @media into @media
@@ -25,8 +25,8 @@ Pass	@supports is CSSGroupingRule
 Pass	@supports rule type
 Pass	Empty @supports rule length
 Fail	insertRule of @import into @supports
-Fail	insertRule into empty @supports at bad index
-Fail	insertRule into @supports updates length
+Pass	insertRule into empty @supports at bad index
+Pass	insertRule into @supports updates length
 Pass	insertRule of valid @media into @supports
 Pass	insertRule of valid style rule into @supports
 Fail	insertRule of invalid @media into @supports

Tests/LibWeb/Text/expected/wpt-import/css/css-nesting/nested-declarations-cssom.txt

@@ -2,8 +2,8 @@ Harness status: OK
 
 Found 12 tests
 
-7 Pass
-5 Fail
+8 Pass
+4 Fail
 Fail	Trailing declarations
 Fail	Mixed declarations
 Fail	CSSNestedDeclarations.style
@@ -12,7 +12,7 @@ Pass	Nested @scope rule
 Fail	Inner rule starting with an ident
 Pass	Inserting a CSSNestedDeclaration rule into style rule
 Pass	Inserting a CSSNestedDeclaration rule into nested group rule
-Fail	Attempting to insert a CSSNestedDeclaration rule into top-level @media rule
+Pass	Attempting to insert a CSSNestedDeclaration rule into top-level @media rule
 Pass	Attempting to insert a CSSNestedDeclaration rule into a stylesheet
 Pass	Attempting to insert a CSSNestedDeclaration rule, empty block
 Pass	Attempting to insert a CSSNestedDeclaration rule, all invalid declarations