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

pkg/compiler/lib/src/js_emitter/class_stub_generator.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.class_stub_generator;
 
 import '../common/names.dart' show Identifiers;
 import '../compiler.dart' show Compiler;
 import '../elements/entities.dart';
 import '../js/js.dart' as jsAst;
@@ skipping 22 matching lines @@
     // TODO(sra): Implement placeholders in VariableDeclaration position:
     //
     //     String constructorName = namer.getNameOfClass(classElement);
     //     return js.statement('function #(#) { #; }',
     //        [ constructorName, fields,
     //            fields.map(
     //                (name) => js('this.# = #', [name, name]))]));
     var typeParameters = const <jsAst.Parameter>[];
     var typeInits = const <jsAst.Expression>[];
     if (hasRtiField) {
-      typeParameters = namer.rtiFieldName;
-      typeInits = js('this.# = #', [namer.rtiFieldName, namer.rtiFieldName]);
+      var rtiName = namer.rtiFieldJsName;
+      typeParameters = rtiName
+      typeInits = js('this.# = #', [rtiName, rtiName]);
     }
     return js('function(#, #) { #; #; this.#();}', [
       fields,
       typeParameters,
       fields.map((name) => js('this.# = #', [name, name])),
       typeInits,
       namer.deferredAction
     ]);
   }
 
@@ skipping 257 matching lines @@
               if (cache === void 0) cache = #tearOff(
                   this, funcs, reflectionInfo, true, [], name).prototype;
               return cache;
             }
           : tearOffGetter(funcs, reflectionInfo, name, isIntercepted);
     }''',
       {'tearOff': tearOffAccessExpression});
 
   return <jsAst.Statement>[tearOffGetter, tearOff];
 }