Importing System.Web.Script.Serialization in Xamarin

I wanted to user JavaScriptSerializer.Deserialize to convert a JSON array string to a list of objects. But this class uses the the System.Web.Script.Serialization in Xamarin namespace. So I wanted to import the System.Web assembly in my project to use the namespace, but System.Web or any similar assembly does not exist in the packages. How can I do that?