Improve web-socket implementation by using making _WebSocketProtocolProcessor a StreamTransformer.

sdk/lib/io/http_impl.dart

Index: sdk/lib/io/http_impl.dart
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index 31099ccf03910fac880959c64a9b97e406ab6096..900bb3423027cc61139946779e95c4a29eb88891 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -445,6 +445,10 @@ class _HttpResponse extends _HttpOutboundMessage<HttpResponse>
     var future = _httpRequest._httpConnection.detachSocket();
     // Close connection so the socket is 'free'.
     close();
+    done.catchError((_) {
+      // Catch any error on done, as they automatically will be propegated to
+      // the websocket.
+    });
     return future;
   }