LibWeb: Add CSSGroupingRule

This is an abstract base class for CSSRules that hold a CSSRuleList.

Userland/Libraries/LibWeb/CSS/CSSGroupingRule.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibWeb/CSS/CSSGroupingRule.h>
+#include <LibWeb/CSS/CSSRuleList.h>
+
+namespace Web::CSS {
+
+CSSGroupingRule::CSSGroupingRule(NonnullRefPtrVector<CSSRule>&& rules)
+    : m_rules(CSSRuleList { move(rules) })
+{
+}
+
+CSSGroupingRule::~CSSGroupingRule()
+{
+}
+
+size_t CSSGroupingRule::insert_rule(StringView const&, size_t)
+{
+    // https://www.w3.org/TR/cssom-1/#insert-a-css-rule
+    TODO();
+}
+
+void CSSGroupingRule::delete_rule(size_t)
+{
+    // https://www.w3.org/TR/cssom-1/#remove-a-css-rule
+    TODO();
+}
+
+}