Remove deprecated string features.

runtime/lib/mirrors_impl.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.
 
 // VM-specific implementation of the dart:mirrors library.
 
 // These values are allowed to be passed directly over the wire.
 bool _isSimpleValue(var value) {
   return (value == null || value is num || value is String || value is bool);
 }
@@ skipping 226 matching lines @@
       case '\b' :
         output = r'\b';
         break;
       case '\t' :
         output = r'\t';
         break;
       case '\v' :
         output = r'\v';
         break;
       default:
-        int code = input.charCodeAt(0);
+        // TODO(lrn): Someone decide if this should combine surrogate pairs.
+        int code = input.codeUnitAt(0);
         if (isNice(code)) {
           output = input;
         } else {
           output = '\\u{${code.toRadixString(16)}}';
         }
         break;
     }
     buf.add(output);
   }
   return buf.toString();
@@ skipping 706 matching lines @@
 
   // Creates a new local InstanceMirror
   static InstanceMirror makeLocalInstanceMirror(Object reflectee)
       native 'Mirrors_makeLocalInstanceMirror';
 
   // Creates a new local mirror for some Object.
   static InstanceMirror reflect(Object reflectee) {
     return makeLocalInstanceMirror(reflectee);
   }
 }