Handle deferred access of unserialized code.

pkg/compiler/lib/src/serialization/task.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.
 
 library dart2js.serialization.task;
 
 import 'dart:async' show EventSink, Future;
 import '../common.dart';
 import '../common/resolution.dart' show ResolutionImpact, ResolutionWorkItem;
 import '../common/tasks.dart' show CompilerTask;
@@ skipping 99 matching lines @@
       sink
         ..add(createSerializer(libraries)
             .toText(const JsonSerializationEncoder()))
         ..close();
     });
   }
 
   void deserializeFromText(Uri sourceUri, String serializedData) {
     measure(() {
       if (deserializer == null) {
-        deserializer = new DeserializerSystemImpl(
-            compiler, compiler.backend.impactTransformer);
+        deserializer = new DeserializerSystemImpl(compiler);
       }
       DeserializerSystemImpl deserializerImpl = deserializer;
       DeserializationContext context = deserializerImpl.deserializationContext;
       Deserializer dataDeserializer = new Deserializer.fromText(
           context, sourceUri, serializedData, const JsonSerializationDecoder());
       context.deserializers.add(dataDeserializer);
     });
   }
 }
 
@@ skipping 24 matching lines @@
 /// elements.
 abstract class DeserializerSystem {
   Future<LibraryElement> readLibrary(Uri resolvedUri);
   bool isDeserialized(Element element);
   bool hasResolvedAst(ExecutableElement element);
   ResolvedAst getResolvedAst(ExecutableElement element);
   bool hasResolutionImpact(Element element);
   ResolutionImpact getResolutionImpact(Element element);
   WorldImpact computeWorldImpact(Element element);
 }