ServiceHostFactory missing in .NET 4.0?

This is driving me nuts, maybe I'm missing something but I'm trying to upgrade a .NET 3.5 application to .NET 4.0 and the only problem I'm running into is this class:

3.5 Code:

   public class ServiceHostFactory : System.ServiceModel.Activation.ServiceHostFactory
    {
        protected override System.ServiceModel.ServiceHost CreateServiceHost(Type serviceType, Uri[] baseAddresses) {
            return new ServiceHost(serviceType, baseAddresses);
        }
    }

When I upgrade to 4.0, it appears that "ServiceHostFactory" doesn't exist (it is red). Going into Object Browser, under System.ServiceModel.Activation, it indeed shows no ServiceHostFactory.

According to this:

http://msdn.microsoft.com/en-us/library/system.servicemodel.activation.servicehostfactory.aspx

It should be supported in 4.0. What am I missing here?