Make IOSink implement StringSink

tests/standalone/io/http_shutdown_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 "dart:async";
@@ skipping 22 matching lines @@
         });
     }
   });
 }
 
 
 void test2(int totalConnections, int outputStreamWrites) {
   // Server which responds without waiting for request body.
   HttpServer.bind().then((server) {
     server.listen((HttpRequest request) {
-      request.response.addString("!dlrow ,olleH");
+      request.response.write("!dlrow ,olleH");
       request.response.close();
     });
 
     int count = 0;
     HttpClient client = new HttpClient();
     for (int i = 0; i < totalConnections; i++) {
       client.get("127.0.0.1", server.port, "/")
         .then((HttpClientRequest request) {
           request.contentLength = -1;
           for (int i = 0; i < outputStreamWrites; i++) {
-            request.addString("Hello, world!");
+            request.write("Hello, world!");
           }
           request.done.catchError((_) {});
           return request.close();
         })
         .then((HttpClientResponse response) {
           response.listen(
             (_) {},
             onDone: () {
               count++;
               if (count == totalConnections) {
@@ skipping 14 matching lines @@
   });
 }
 
 
 void test3(int totalConnections) {
   // Server which responds when request body has been received.
   HttpServer.bind().then((server) {
 
   server.listen((HttpRequest request) {
     request.listen((_) {}, onDone: () {
-      request.response.addString("!dlrow ,olleH");
+      request.response.write("!dlrow ,olleH");
       request.response.close();
     });
   });
 
   int count = 0;
   HttpClient client = new HttpClient();
   for (int i = 0; i < totalConnections; i++) {
     client.get("127.0.0.1", server.port, "/")
       .then((HttpClientRequest request) {
         request.contentLength = -1;
-        request.addString("Hello, world!");
+        request.write("Hello, world!");
         return request.close();
       })
       .then((HttpClientResponse response) {
         response.listen((_) {}, onDone: () {
           count++;
           if (count == totalConnections) {
             client.close();
             server.close();
           }
         });
@@ skipping 46 matching lines @@
         },
         onError: (error) { });
 
     // Create a number of client requests and keep then active. Then
     // close the client and wait for the server to lose all active
     // connections.
     var client= new HttpClient();
     for (int i = 0; i < totalConnections; i++) {
       client.post("127.0.0.1", server.port, "/")
         .then((request) {
-            request.add([0]);
+            request.writeBytes([0]);
             // TODO(sgjesse): Make this test work with
             //request.response instead of request.close() return
             //return request.response;
             request.done.catchError((e) {});
             return request.close();
           })
         .then((response) { })
         .catchError((e) { }, test: (e) => e is HttpParserException);
     }
     bool clientClosed = false;
@@ skipping 19 matching lines @@
   test1(10);
   test2(1, 10);
   test2(10, 10);
   test2(10, 1000);
   test3(1);
   test3(10);
   test4();
   test5(1);
   test5(10);
 }