Remove deprecated string features.

runtime/lib/integers_patch.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.
 // Dart core library.
 
 // VM implementation of int.
 
 patch class int {
   static int _parse(String str) native "Integer_parse";
 
@@ skipping 32 matching lines @@
     const NA = 99;
     const List<int> digits = const <int>[
       00, 01, 02, 03, 04, 05, 06, 07, 08, 09, NA, NA, NA, NA, NA, NA,  // 0x30
       NA, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,  // 0x40
       25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, NA, NA, NA, NA, NA,  // 0x50
       NA, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24,  // 0x60
       25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, NA, NA, NA, NA, NA,  // 0x70
     ];
 
     int i = 0;
-    int code = source.charCodeAt(i);
+    int code = source.codeUnitAt(i);
     if (code == 0x2d || code == 0x2b) { // Starts with a plus or minus-sign.
       negative = (code == 0x2d);
       if (source.length == 1) return onError(source);
       i = 1;
-      code = source.charCodeAt(i);
+      code = source.codeUnitAt(i);
     }
     do {
       if (code < 0x30 || code > 0x7f) return onError(source);
       int digit = digits[code - 0x30];
       if (digit >= radix) return onError(source);
       result = result * radix + digit;
       i++;
       if (i == source.length) break;
-      code = source.charCodeAt(i);
+      code = source.codeUnitAt(i);
     } while (true);
     return negative ? -result : result;
   }
 }