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

pkg/compiler/lib/src/js_emitter/startup_emitter/fragment_emitter.dart

 // Copyright (c) 2015, 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.
 
 part of dart2js.js_emitter.startup_emitter.model_emitter;
 
 /// The name of the property that stores the tear-off getter on a static
 /// function.
 ///
 /// This property is only used when isolates are used.
@@ skipping 637 matching lines @@
     js.Name name = cls.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.isNative || !cls.isDirectlyInstantiated) {
       return js.js('function #() { }', name);
     }
 
     List<js.Name> fieldNames =
         cls.fields.map((Field field) => field.name).toList();
     if (cls.hasRtiField) {
-      fieldNames.add(namer.rtiFieldName);
+      fieldNames.add(namer.rtiFieldJsName);
     }
 
     Iterable<js.Name> assignments = fieldNames.map((js.Name field) {
       return js.js("this.#field = #field", {"field": field});
     });
 
     // TODO(sra): Cache 'this' in a one-character local for 4 or more uses of
     // 'this'. i.e. "var _=this;_.a=a;_.b=b;..."
 
     // TODO(sra): Separate field and field initializer parameter names so the
@@ skipping 716 matching lines @@
     }
     statements.add(js.js.statement("setOrUpdateInterceptorsByTag(#);",
         js.objectLiteral(interceptorsByTag)));
     statements.add(
         js.js.statement("setOrUpdateLeafTags(#);", js.objectLiteral(leafTags)));
     statements.addAll(subclassAssignments);
 
     return new js.Block(statements);
   }
 }