Remove StreamSink(replaced by EventSink) and make IOSink extend EventSink.

tests/standalone/io/secure_socket_test.dart

Index: tests/standalone/io/secure_socket_test.dart
diff --git a/tests/standalone/io/secure_socket_test.dart b/tests/standalone/io/secure_socket_test.dart
index 8af2b2893128508b260475c9fe9cdec38449acc2..09a5852fddb28d52624ef620a7732adf4a6804ab 100644
--- a/tests/standalone/io/secure_socket_test.dart
+++ b/tests/standalone/io/secure_socket_test.dart
@@ -23,7 +23,7 @@ Future<HttpServer> startServer() {
         onDone: () {
           request.response.contentLength = 100;
           for (int i = 0; i < 10; i++) {
-            request.response.writeBytes([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
+            request.response.add([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]);
           }
           request.response.close();
         });