Remove deprecated string features.

utils/css/parser.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 
 /**
  * A simple recursive descent parser for CSS.
  */
 class Parser {
   Tokenizer tokenizer;
 
   var _fs;                        // If non-null filesystem to read files.
@@ skipping 981 matching lines @@
       return c - 55;
     } else {
       return -1;
     }
   }
 
   static int parseHex(String hex) {
     var result = 0;
 
     for (int i = 0; i < hex.length; i++) {
-      var digit = _hexDigit(hex.charCodeAt(i));
+      var digit = _hexDigit(hex.codeUnitAt(i));
       if (digit < 0) {
         throw new HexNumberException();
       }
       result = (result << 4) + digit;
     }
 
     return result;
   }
 }
 
 /** Not a hex number. */
 class HexNumberException implements Exception {
   HexNumberException();
 }