Refactor CompilerOutput

tests/compiler/dart2js/preserve_uris_test.dart

 // Copyright (c) 2014, 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:expect/expect.dart';
 import 'package:async_helper/async_helper.dart';
+import 'package:compiler/compiler_new.dart';
 import 'memory_compiler.dart' show runCompiler, OutputCollector;
 
 const MEMORY_SOURCE_FILES = const <String, String>{
   'main.dart': """
 library main;
 
 @MirrorsUsed(targets: const ['main', 'lib'])
 import 'dart:mirrors';
 import 'lib.dart';
 
@@ skipping 21 matching lines @@
 };
 
 runTest(bool preserveUris) async {
   OutputCollector collector = new OutputCollector();
   var options = ["--minify"];
   if (preserveUris) options.add("--preserve-uris");
   await runCompiler(
       memorySourceFiles: MEMORY_SOURCE_FILES,
       outputProvider: collector,
       options: options);
-  String jsOutput = collector.getOutput('', 'js');
+  String jsOutput = collector.getOutput('', OutputType.js);
   Expect.equals(preserveUris, jsOutput.contains("main.dart"));
   Expect.equals(preserveUris, jsOutput.contains("lib.dart"));
 }
 
 void main() {
   asyncTest(() async {
     await runTest(true);
     await runTest(false);
   });
 }