Add 'part of' in dart2js code.

lib/compiler/implementation/scanner/keyword.dart

 // Copyright (c) 2011, 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.
 
+part of scanner;
+
 /**
  * A keyword in the Dart programming language.
  */
 class Keyword implements SourceString {
   static const List<Keyword> values = const <Keyword> [
       const Keyword("assert"),
       const Keyword("break"),
       const Keyword("case"),
       const Keyword("catch"),
       const Keyword("class"),
@@ skipping 207 matching lines @@
   final Keyword keyword;
 
   LeafKeywordState(String syntax) : keyword = Keyword.keywords[syntax];
 
   bool isLeaf() => true;
 
   KeywordState next(int c) => null;
 
   String toString() => keyword.syntax;
 }