Add 'part of' in dart2js code.

lib/compiler/implementation/scanner/array_based_scanner.dart

Index: lib/compiler/implementation/scanner/array_based_scanner.dart
diff --git a/lib/compiler/implementation/scanner/array_based_scanner.dart b/lib/compiler/implementation/scanner/array_based_scanner.dart
index 986caf9fc8050661fbb7fc3f0489dbee1d7c2b27..f0cb22ffe3071c5b9bac2b39fd5088b5be05856d 100644
--- a/lib/compiler/implementation/scanner/array_based_scanner.dart
+++ b/lib/compiler/implementation/scanner/array_based_scanner.dart
@@ -2,6 +2,8 @@
 // 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.
 
+part of scanner_implementation;
+
 abstract
 class ArrayBasedScanner<S extends SourceString> extends AbstractScanner<S> {
   int get charOffset => byteOffset + extraCharOffset;