Don't use magic strings/properties to communicate between compiler and runtime.

pkg/compiler/lib/src/js_emitter/lazy_emitter/model_emitter.dart

 // Copyright (c) 2014, 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 dart2js.js_emitter.lazy_emitter.model_emitter;
 
 import 'package:js_runtime/shared/embedded_names.dart'
     show
         CREATE_NEW_ISOLATE,
         DEFERRED_LIBRARY_URIS,
@@ skipping 609 matching lines @@
   }
 
   js.Expression _generateConstructor(Class cls) {
     List<js.Name> fieldNames = const <js.Name>[];
 
     // If the class is not directly instantiated we only need it for inheritance
     // or RTI. In either case we don't need its fields.
     if (cls.isDirectlyInstantiated && !cls.isNative) {
       fieldNames = cls.fields.map((Field field) => field.name).toList();
       if (cls.hasRtiField) {
-        fieldNames.add(namer.rtiFieldName);
+        fieldNames.add(namer.rtiFieldJsName);
       }
     }
     js.Name name = cls.name;
 
     Iterable<js.Name> assignments = fieldNames.map((js.Name field) {
       return js.js("this.#field = #field", {"field": field});
     });
 
     return js.js('function #(#) { # }', [name, fieldNames, assignments]);
   }
@@ skipping 629 matching lines @@
   #eagerClasses;
 
   var end = Date.now();
   // print('Setup: ' + (end - start) + ' ms.');
 
   #invokeMain;  // Start main.
 
 })(Date.now(), #code)
 }""";
 }