Refactor unittests

tests/compiler/dart2js/serialization/helper.dart

 // Copyright (c) 2016, 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_helper;
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:compiler/src/commandline_options.dart';
@@ skipping 10 matching lines @@
 import 'package:compiler/src/serialization/json_serializer.dart';
 import 'package:compiler/src/serialization/modelz.dart';
 import 'package:compiler/src/serialization/resolved_ast_serialization.dart';
 import 'package:compiler/src/serialization/serialization.dart';
 import 'package:compiler/src/serialization/task.dart';
 import 'package:compiler/src/tokens/token.dart';
 import 'package:compiler/src/universe/call_structure.dart';
 import 'package:compiler/src/universe/world_impact.dart';
 import 'package:compiler/src/universe/use.dart';
 
-import 'memory_compiler.dart';
+import '../memory_compiler.dart';
 
 class Arguments {
   final String filename;
   final bool loadSerializedData;
   final bool saveSerializedData;
   final String serializedDataFileName;
   final bool verbose;
 
   const Arguments({
     this.filename,
@@ skipping 298 matching lines @@
 
   @override
   void onElement(Element element, ObjectDecoder getDecoder(String tag)) {
     ObjectDecoder decoder = getDecoder(RESOLVED_AST_TAG);
     if (decoder != null) {
       _decoderMap[element] = decoder;
     }
   }
 }