Remove deprecated string features.

utils/tests/string_encoding/utf8_test.dart

 #!/usr/bin/env 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.
 
 library utf8_tests;
 import 'dunit.dart';
 import '../../../lib/utf/utf.dart';
 
 void main() {
@@ skipping 448 matching lines @@
   void testIterableMethods() {
     IterableUtf8Decoder englishDecoder = decodeUtf8AsIterable(testEnglishUtf8);
     // get the first character
     Expect.equals(testEnglishUtf8[0], englishDecoder.first);
     // get the whole translation using the Iterable interface
     Expect.stringEquals(testEnglishPhrase,
         new String.fromCharCodes(new List<int>.from(englishDecoder)));
 
     IterableUtf8Decoder kataDecoder = decodeUtf8AsIterable(testKatakanaUtf8);
     // get the first character
-    Expect.equals(testKatakanaPhrase.charCodes[0], kataDecoder.first);
+    Expect.equals(testKatakanaPhrase.codeUnits[0], kataDecoder.first);
     // get the whole translation using the Iterable interface
     Expect.stringEquals(testKatakanaPhrase,
         new String.fromCharCodes(new List<int>.from(kataDecoder)));
   }
 }