Refactor CompilerOutput

tests/compiler/dart2js/use_strict_test.dart

 // Copyright (c) 2011, 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.
 
 import 'package:async_helper/async_helper.dart';
+import 'package:compiler/compiler_new.dart';
 import 'package:expect/expect.dart';
 import 'memory_compiler.dart';
 
 // Use strict does not allow parameters or locals named "arguments" or "eval".
 
 const MEMORY_SOURCE_FILES = const {
   'main.dart': '''
       class A {
         final arguments;
         final eval;
@@ skipping 27 matching lines @@
           print(list[i].foo(i, i + 1));
         }
       }'''
 };
 
 main() {
   OutputCollector collector = new OutputCollector();
   asyncTest(() async {
     await runCompiler(
         memorySourceFiles: MEMORY_SOURCE_FILES, outputProvider: collector);
-    String jsOutput = collector.getOutput('', 'js');
+    String jsOutput = collector.getOutput('', OutputType.js);
 
     // Skip comments.
     List<String> lines = jsOutput.split("\n");
     RegExp commentLine = new RegExp(r' *//');
     String filtered =
         lines.where((String line) => !commentLine.hasMatch(line)).join("\n");
 
     // TODO(floitsch): we will need to adjust this filter if we start using
     // 'eval' or 'arguments' ourselves. Currently we disallow any 'eval' or
     // 'arguments'.
     RegExp re = new RegExp(r'[^\w$](arguments|eval)[^\w$]');
     Expect.isFalse(re.hasMatch(filtered));
   });
 }