Revert "Remove Compiler.assembledCode."

tests/compiler/dart2js/analyze_only_test.dart

 // Copyright (c) 2012, 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.
 
 // Smoke test of the dart2js compiler API.
 library analyze_only;
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import "package:async_helper/async_helper.dart";
 
 import '../../utils/dummy_compiler_test.dart' as dummy;
 import 'package:compiler/compiler.dart';
 
 import 'package:compiler/src/dart2jslib.dart' show
     MessageKind;
 
-import 'output_collector.dart';
-
 runCompiler(String main, List<String> options,
             onValue(String code, List errors, List warnings)) {
   List errors = new List();
   List warnings = new List();
 
   Future<String> localProvider(Uri uri) {
     if (uri.scheme != 'main') return dummy.provider(uri);
     return new Future<String>.value(main);
   }
 
   void localHandler(Uri uri, int begin, int end,
                     String message, Diagnostic kind) {
     dummy.handler(uri, begin, end, message, kind);
     if (kind == Diagnostic.ERROR) {
       errors.add(message);
     } else if (kind == Diagnostic.WARNING) {
       warnings.add(message);
     }
   }
 
   print('-----------------------------------------------');
   print('main source:\n$main');
   print('options: $options\n');
   asyncStart();
-  OutputCollector outputCollector = new OutputCollector();
-  Future<CompilationResult> result =
+  Future<String> result =
       compile(new Uri(scheme: 'main'),
               new Uri(scheme: 'lib', path: '/'),
               new Uri(scheme: 'package', path: '/'),
-              localProvider, localHandler, options, outputCollector);
-  result.then((_) {
-    onValue(outputCollector.getOutput('', 'js'), errors, warnings);
+              localProvider, localHandler, options);
+  result.then((String code) {
+    onValue(code, errors, warnings);
   }, onError: (e) {
     throw 'Compilation failed: ${Error.safeToString(e)}';
   }).then(asyncSuccess).catchError((error, stack) {
     print('\n\n-----------------------------------------------');
     print('main source:\n$main');
     print('options: $options\n');
     print('threw:\n $error\n$stack');
     print('-----------------------------------------------\n\n');
     throw error;
   });
@@ skipping 109 matching lines @@
   // --analyze-signatures-only implies --analyze-only
   runCompiler(
     "",
     ['--analyze-signatures-only', '--analyze-all'],
     (String code, List errors, List warnings) {
       Expect.isNull(code);
       Expect.isTrue(errors.isEmpty);
       Expect.isTrue(warnings.isEmpty);
     });
 }