dart2js: don't reify type variables for reflectable typedefs.

pkg/compiler/lib/src/js_emitter/metadata_collector.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.
 
 part of dart2js.js_emitter;
 
 class MetadataCollector {
   final Compiler _compiler;
   final Emitter _emitter;
 
@@ skipping 73 matching lines @@
         _backend.constants.getConstantForMetadata(annotation);
     if (constant == null) {
       _compiler.internalError(annotation, 'Annotation value is null.');
       return -1;
     }
     return addGlobalMetadata(
         jsAst.prettyPrint(
             _emitter.constantReference(constant.value), _compiler).getText());
   }
 
-  int reifyType(DartType type) {
+  int reifyType(DartType type, {bool ignoreTypeVariables: false}) {
     return reifyTypeForOutputUnit(type,
-                                  _compiler.deferredLoadTask.mainOutputUnit);
+                                  _compiler.deferredLoadTask.mainOutputUnit,
+                                  ignoreTypeVariables: ignoreTypeVariables);
   }
 
-  int reifyTypeForOutputUnit(DartType type, OutputUnit outputUnit) {
+  int reifyTypeForOutputUnit(DartType type, OutputUnit outputUnit,
+                             {bool ignoreTypeVariables: false}) {
     jsAst.Expression representation =
         _backend.rti.getTypeRepresentation(
             type,
             (variable) {
+              if (ignoreTypeVariables) return new jsAst.LiteralNull();
               return js.number(
                   _typeVariableHandler.reifyTypeVariable(
                       variable.element));
             },
             (TypedefType typedef) {
               return _backend.isAccessibleByReflection(typedef.element);
             });
 
     return addTypeInOutputUnit(
         jsAst.prettyPrint(representation, _compiler).getText(), outputUnit);
@@ skipping 32 matching lines @@
       // TODO(ahe): Why is metadata sometimes null?
       if (link != null) {
         for (; !link.isEmpty; link = link.tail) {
           metadata.add(reifyMetadata(link.head));
         }
       }
       return metadata;
     });
   }
 }