LibWeb: Parse scroll() for the animation-timeline CSS property

Author: https://github.com/Calme1709
Commit: https://github.com/LadybirdBrowser/ladybird/commit/7d70714eac3
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/6912
Reviewed-by: https://github.com/AtkinsSJ ✅

Libraries/LibWeb/CSS/StyleValues/ScrollFunctionStyleValue.cpp

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2025, Callum Law <callumlaw1709@outlook.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include "ScrollFunctionStyleValue.h"
+
+namespace Web::CSS {
+
+String ScrollFunctionStyleValue::to_string(SerializationMode) const
+{
+    StringBuilder builder;
+    builder.append("scroll("sv);
+
+    if (m_scroller != Scroller::Nearest)
+        builder.append(CSS::to_string(m_scroller));
+
+    if (m_axis != Axis::Block) {
+        if (m_scroller != Scroller::Nearest)
+            builder.append(' ');
+        builder.append(CSS::to_string(m_axis));
+    }
+
+    builder.append(')');
+    return builder.to_string_without_validation();
+}
+
+}