Remove .writeStream, .consume and rewrite IOSink to correctly implement a (sane) well-defined behav…

tests/standalone/io/http_server_response_test.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
 
 import "package:expect/expect.dart";
@@ skipping 38 matching lines @@
       Expect.equals(request.response, response);
       server.close();
     });
   });
 }
 
 void testResponseAddStream() {
   int bytes = new File(new Options().script).lengthSync();
 
   testServerRequest((server, request) {
-    request.response.writeStream(new File(new Options().script).openRead())
+    request.response.addStream(new File(new Options().script).openRead())
         .then((response) {
           response.close();
           response.done.then((_) => server.close());
         });
   }, bytes: bytes);
 
   testServerRequest((server, request) {
-    request.response.writeStream(new File(new Options().script).openRead())
+    request.response.addStream(new File(new Options().script).openRead())
         .then((response) {
-          request.response.writeStream(new File(new Options().script).openRead())
+          request.response.addStream(new File(new Options().script).openRead())
               .then((response) {
                 response.close();
                 response.done.then((_) => server.close());
               });
         });
   }, bytes: bytes * 2);
 
   testServerRequest((server, request) {
     var controller = new StreamController();
-    request.response.writeStream(controller.stream)
+    request.response.addStream(controller.stream)
         .then((response) {
           response.close();
           response.done.then((_) => server.close());
         });
     controller.close();
   }, bytes: 0);
 }
 
 void testBadResponseAdd() {
   testServerRequest((server, request) {
@@ skipping 45 matching lines @@
     }, test: (e) => e is HttpException);
   });
 }
 
 void main() {
   testResponseDone();
   testResponseAddStream();
   testBadResponseAdd();
   testBadResponseClose();
 }