Remove deprecated string features.

tests/standalone/io/mime_multipart_parser_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.
 
 import 'dart:math';
 
 part "../../../sdk/lib/io/http_parser.dart";
 part "../../../sdk/lib/io/mime_multipart_parser.dart";
 
 void testParse(String message,
@@ skipping 24 matching lines @@
     parser.partDataReceived = (List<int> data) {
       if (currentPart == null) currentPart = new List<int>();
       currentPart.addAll(data);
     };
     parser.partEnd = (lastPart) {
       Expect.isFalse(lastPartCalled);
       lastPartCalled = lastPart;
       if (expectedParts[partCount] != null) {
         List<int> expectedPart;
         if (expectedParts[partCount] is String) {
-          expectedPart = expectedParts[partCount].charCodes;
+          expectedPart = expectedParts[partCount].codeUnits;
         } else {
           expectedPart = expectedParts[partCount];
         }
         Expect.listEquals(expectedPart, currentPart);
       }
       currentPart = null;
       partCount++;
       if (lastPart) Expect.equals(expectedParts.length, partCount);
     };
 
@@ skipping 15 matching lines @@
       int parsed =
           parser.update(data.getRange(pos, writeLength), 0, writeLength);
       unparsed = writeLength - parsed;
       Expect.equals(0, unparsed);
     }
     Expect.isTrue(lastPartCalled);
   }
 
   // Test parsing the data three times delivering the data in
   // different chunks.
-  List<int> data = message.charCodes;
+  List<int> data = message.codeUnits;
   testWrite(data);
   testWrite(data, 10);
   testWrite(data, 2);
   testWrite(data, 1);
 }
 
 void testParseValid() {
   String message;
   Map headers;
   Map headers1;
@@ skipping 239 matching lines @@
 \r
 Body2\r
 --xxx\r\n""";
   Expect.throws(() => testParse(message, "xxx", null, [null, null]));
 }
 
 void main() {
   testParseValid();
   testParseInvalid();
 }