Add 'part of' in dart2js code.

lib/compiler/implementation/scanner/scanner_implementation.dart

Index: lib/compiler/implementation/scanner/scanner_implementation.dart
diff --git a/lib/compiler/implementation/scanner/scanner_implementation.dart b/lib/compiler/implementation/scanner/scanner_implementation.dart
index 5bc43e71ce3e80bddc2eebb7b6e5ed29b07a4c89..1bd83272daa2624b185936135730173b60f9f1c6 100644
--- a/lib/compiler/implementation/scanner/scanner_implementation.dart
+++ b/lib/compiler/implementation/scanner/scanner_implementation.dart
@@ -2,8 +2,10 @@
 // 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('scanner_implementation');
-#import('scannerlib.dart');
-#import('../util/util.dart');
-#import('../util/characters.dart');
-#source('array_based_scanner.dart');
+library scanner_implementation;
+
+import 'scannerlib.dart';
+import '../util/util.dart';
+import '../util/characters.dart';
+
+part 'array_based_scanner.dart';