Remove deprecated string features.

tests/standalone/io/http_server_early_client_close_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.
 
 import "dart:async";
 import "dart:io";
 import "dart:isolate";
 
 void sendData(List<int> data, int port) {
   Socket.connect("127.0.0.1", port).then((socket) {
@@ skipping 39 matching lines @@
           Expect.isFalse(calledOnError);
           Expect.equals(exception, e.error.message);
           Expect.equals(expectRequest, calledOnRequest);
           calledOnError = true;
           port.close();
           c.complete(null);
         });
 
     List<int> d;
     if (data is List<int>) d = data;
-    if (data is String) d = data.charCodes;
+    if (data is String) d = data.codeUnits;
     if (d == null) Expect.fail("Invalid data");
     sendData(d, server.port);
 
     return c.future;
   }
 
   final data;
   final String exception;
   final bool expectRequest;
 }
@@ skipping 38 matching lines @@
     server.listen(
       (request) {
         String name = new Options().script;
         new File(name).openRead().pipe(request.response);
       },
       onError: (e) { /* ignore */ });
 
     var count = 0;
     makeRequest() {
       Socket.connect("127.0.0.1", server.port).then((socket) {
-        var data = "GET / HTTP/1.1\r\nContent-Length: 0\r\n\r\n".charCodes;
+        var data = "GET / HTTP/1.1\r\nContent-Length: 0\r\n\r\n".codeUnits;
         socket.add(data);
         socket.close();
         socket.done.then((_) {
           socket.destroy();
           if (++count < 10) {
             makeRequest();
           } else {
             server.close();
           }
         });
       });
     }
     makeRequest();
   });
 }
 
 void main() {
   testEarlyClose1();
 //  testEarlyClose2();
 }