Updated reference assembly

Author: alefranz

src/Http/WebUtilities/ref/Microsoft.AspNetCore.WebUtilities.netcoreapp.cs

@@ -145,8 +145,12 @@ protected override void Dispose(bool disposing) { }
         public override int Peek() { throw null; }
         public override int Read() { throw null; }
         public override int Read(char[] buffer, int index, int count) { throw null; }
-        [System.Diagnostics.DebuggerStepThroughAttribute]
+        public override int Read(System.Span<char> buffer) { throw null; }
         public override System.Threading.Tasks.Task<int> ReadAsync(char[] buffer, int index, int count) { throw null; }
+        [System.Diagnostics.DebuggerStepThroughAttribute]
+        public override System.Threading.Tasks.ValueTask<int> ReadAsync(System.Memory<char> buffer, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) { throw null; }
+        [System.Diagnostics.DebuggerStepThroughAttribute]
+        public override System.Threading.Tasks.Task<string> ReadLineAsync() { throw null; }
     }
     public partial class HttpResponseStreamWriter : System.IO.TextWriter
     {