LibWeb: Add RatioStyleValue and parsing

Author: https://github.com/AtkinsSJ
Commit: 5e3da93f1a
Pull-request: https://github.com/SerenityOS/serenity/pull/19323

Userland/Libraries/LibWeb/CSS/Ratio.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, Sam Atkins <atkinssj@serenityos.org>
+ * Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -19,6 +19,23 @@ public:
 
     ErrorOr<String> to_string() const;
 
+    bool operator==(Ratio const& other) const
+    {
+        return value() == other.value();
+    }
+
+    int operator<=>(Ratio const& other) const
+    {
+        auto this_value = value();
+        auto other_value = other.value();
+
+        if (this_value < other_value)
+            return -1;
+        if (this_value > other_value)
+            return 1;
+        return 0;
+    }
+
 private:
     float m_first_value { 0 };
     float m_second_value { 1 };