Updated reference assemblies

Author: alefranz

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

@@ -149,6 +149,7 @@ protected override void Dispose(bool disposing) { }
         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; }
+        public override string ReadLine() { throw null; }
         [System.Diagnostics.DebuggerStepThroughAttribute]
         public override System.Threading.Tasks.Task<string> ReadLineAsync() { throw null; }
     }