Bah, Humbug!

I was hoping  typeof(T).IsValueType would get evaluated during JIT
compilation which would allow for dead code elimination, but alas:
https://github.com/dotnet/corefx/issues/16217

src/SignalR/server/Core/src/Internal/AsyncEnumeratorAdapters.cs

@@ -15,13 +15,7 @@ internal static class AsyncEnumeratorAdapters
  public static IAsyncEnumerator<object> GetAsyncEnumeratorFromAsyncEnumerable<T>(IAsyncEnumerable<T> asyncEnumerable, CancellationToken cancellationToken = default(CancellationToken))
  {
  var enumerator = asyncEnumerable.GetAsyncEnumerator(cancellationToken);
-
- if (typeof(T).IsValueType)
- {
- return new BoxedAsyncEnumerator<T>(enumerator);
- }
-
- return (IAsyncEnumerator<object>)enumerator;
+ return enumerator as IAsyncEnumerator<object> ?? new BoxedAsyncEnumerator<T>(enumerator);
  }
 
  public static IAsyncEnumerator<object> GetAsyncEnumeratorFromChannel<T>(ChannelReader<T> channel, CancellationToken cancellationToken = default(CancellationToken))