Contains polyfills from the mscorlib for .NET Framework 3.5. Add: System.IProgress System.Progress System.Collections.Generic System.Collections.Generic.IReadOnlyCollection System.Collections.Generic.IReadOnlyDictionary System.Collections.Generic.IReadOnlyList System.Collections.Generic.IReadOnlySet System.Net.DnsEndPoint System.Threading.SpinWait System.Threading.Volatile Extensions: System.ArgumentNullExceptionEx: - ThrowIfNull System.EventHandlerEx: - EventHandlerEx<TEventArgs> System.StringEx: - Join<T> - IsNullOrWhiteSpace System.EnumEx: - TryParse<TEnum> System.EnvironmentEx: - Is64BitProcess - Is64BitOperatingSystem System.OperatingSystemEx: - VersionString - IsOSPlatform - IsOSPlatformVersionAtLeast System.Text.StringBuilderEx: - Clear