Emit to StreamCodeOutput instead of CodeBuffer.

pkg/compiler/lib/src/dart2js.dart

 // Copyright (c) 2013, 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.cmdline;
 
 import 'dart:async'
     show Future, EventSink;
 import 'dart:convert' show UTF8, LineSplitter;
 import 'dart:io'
     show exit, File, FileMode, Platform, RandomAccessFile, FileSystemException,
          stdin, stderr;
 
 import '../compiler.dart' as api;
-import 'source_file.dart';
+import 'io/source_file.dart';
 import 'source_file_provider.dart';
 import 'filenames.dart';
 import 'util/uri_extras.dart';
 import 'util/util.dart' show stackTraceFilePrefix;
 import 'util/command_line.dart';
 import 'package:_internal/libraries.dart';
 
 const String LIBRARY_ROOT = '../../../../../sdk';
 const String OUTPUT_LANGUAGE_DART = 'Dart';
 
@@ skipping 678 matching lines @@
       } else if (exitCode == 253) {
         print(">>> TEST CRASH");
       } else {
         print(">>> TEST FAIL");
       }
       stderr.writeln(">>> EOF STDERR");
       subscription.resume();
     });
   });
 }