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

pkg/compiler/lib/src/js_emitter/full_emitter/class_emitter.dart

 // Copyright (c) 2013, 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.full_emitter.class_emitter;
 
 import '../../common.dart';
 import '../../common/names.dart' show Names;
 import '../../elements/resolution_types.dart' show ResolutionDartType;
 import '../../deferred_load.dart' show OutputUnit;
@@ skipping 39 matching lines @@
       jsAst.Name mixinName = mixinApplication.mixinClass.name;
       superName = new CompoundName([superName, Namer.literalPlus, mixinName]);
       emitter.needsMixinSupport = true;
     }
 
     ClassBuilder builder = new ClassBuilder.forClass(classElement, namer);
     builder.superName = superName;
     emitConstructorsForCSP(cls);
     emitFields(cls, builder);
     if (cls.hasRtiField) {
-      builder.addField(namer.rtiFieldName);
+      builder.addField(namer.rtiFieldJsName);
     }
     emitCheckedClassSetters(cls, builder);
     emitClassGettersSettersForCSP(cls, builder);
     emitInstanceMembers(cls, builder);
     emitStubs(cls.callStubs, builder);
     emitStubs(cls.typeVariableReaderStubs, builder);
     emitRuntimeTypeInformation(cls, builder);
     emitNativeInfo(cls, builder);
 
     if (classElement == backend.helpers.closureClass) {
@@ skipping 368 matching lines @@
         : new Selector.setter(
             new Name(member.name, member.library, isSetter: true));
     String reflectionName = emitter.getReflectionName(selector, name);
     if (reflectionName != null) {
       var reflectable =
           js(backend.mirrorsData.isAccessibleByReflection(member) ? '1' : '0');
       builder.addPropertyByName('+$reflectionName', reflectable);
     }
   }
 }