Default Infinity Values Produce the `∞` Character

To reproduce:

```csharp
public interface IUseInfinity
{
  void Use(double value = double.PositiveInfinity);
}

public static class Test
{
  public static void Go()
  {
    var expectations = Rock.Create<IUseInfinity>();
  }
}
```

This produces `public void Use(double @value = ∞)` in the mock.

This was found on `StackExchange.Redis.IBatch`.