Remove deprecated string features.

tests/standalone/io/raw_secure_socket_pause_test.dart

 // Copyright (c) 2012, 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";
 import "dart:io";
 import "dart:isolate";
 
 
 void main() {
-  List<int> message = "GET / HTTP/1.0\r\nHost: www.google.dk\r\n\r\n".charCodes;
+  List<int> message = "GET / HTTP/1.0\r\nHost: www.google.dk\r\n\r\n".codeUnits;
   int written = 0;
   List<String> chunks = <String>[];
   SecureSocket.initialize();
   // TODO(whesse): Use a Dart HTTPS server for this test.
   // The Dart HTTPS server works on bleeding-edge, but not on IOv2.
   // When we use a Dart HTTPS server, allow --short_socket_write. The flag
   // causes fragmentation of the client hello message, which doesn't seem to
   // work with www.google.dk.
   RawSecureSocket.connect("www.google.dk", 443).then((socket) {
     StreamSubscription subscription;
@@ skipping 45 matching lines @@
           String fullPage = chunks.join();
           Expect.isTrue(fullPage.contains('</body></html>'));
           break;
         default: throw "Unexpected event $event";
       }
       }, onError: (AsyncError a) {
         Expect.fail("onError handler of RawSecureSocket stream hit: $a");
       });
   });
 }