Remove deprecated string features.

sdk/lib/io/http_headers.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.
 
 part of dart.io;
 
 class _HttpHeaders implements HttpHeaders {
   _HttpHeaders() : _headers = new Map<String, List<String>>();
 
   List<String> operator[](String name) {
@@ skipping 306 matching lines @@
 
     void writeBuffer() {
       connection._writeFrom(buffer, 0, bufferPos);
       bufferPos = 0;
     }
 
     // Format headers.
     _headers.forEach((String name, List<String> values) {
       bool fold = _foldHeader(name);
       List<int> nameData;
-      nameData = name.charCodes;
+      nameData = name.codeUnits;
       int nameDataLen = nameData.length;
       if (nameDataLen + 2 > bufferSize - bufferPos) writeBuffer();
       buffer.setRange(bufferPos, nameDataLen, nameData);
       bufferPos += nameDataLen;
       buffer[bufferPos++] = _CharCode.COLON;
       buffer[bufferPos++] = _CharCode.SP;
       for (int i = 0; i < values.length; i++) {
-        List<int> data = values[i].charCodes;
+        List<int> data = values[i].codeUnits;
         int dataLen = data.length;
         // Worst case here is writing the name, value and 6 additional bytes.
         if (nameDataLen + dataLen + 6 > bufferSize - bufferPos) writeBuffer();
         if (i > 0) {
           if (fold) {
             buffer[bufferPos++] = _CharCode.COMMA;
             buffer[bufferPos++] = _CharCode.SP;
           } else {
             buffer[bufferPos++] = _CharCode.CR;
             buffer[bufferPos++] = _CharCode.LF;
@@ skipping 337 matching lines @@
 
   String name;
   String value;
   DateTime expires;
   int maxAge;
   String domain;
   String path;
   bool httpOnly = false;
   bool secure = false;
 }