Refactor CompilerOutput

tests/compiler/dart2js/serialization/compilation_test_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_compilation_test;
 
 import 'dart:async';
 import 'package:async_helper/async_helper.dart';
+import 'package:compiler/compiler_new.dart';
 import 'package:compiler/src/commandline_options.dart';
 import 'package:compiler/src/filenames.dart';
 import '../memory_compiler.dart';
 import 'helper.dart';
 import 'test_data.dart';
 import '../output_collector.dart';
 
 /// Number of tests that are not part of the automatic test grouping.
 int SKIP_COUNT = 2;
 
@@ skipping 37 matching lines @@
       options.add(Flags.enableCheckedMode);
     }
     await runCompiler(
         entryPoint: entryPoint,
         memorySourceFiles: sourceFiles,
         resolutionInputs: resolutionInputs,
         options: options,
         outputProvider: outputCollector);
   });
   if (verbose) {
-    print(outputCollector.getOutput('', 'js'));
+    print(outputCollector.getOutput('', OutputType.js));
   }
 }