pkg/compiler: fix imports

pkg/compiler/lib/src/tokens/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.
 
 library dart2js.tokens.keywords;
 
 import '../util/characters.dart' as Characters show $a;
-
 import 'precedence.dart' show PrecedenceInfo;
 import 'precedence_constants.dart' as Precedence
     show AS_INFO, IS_INFO, KEYWORD_INFO;
 
 /**
  * A keyword in the Dart programming language.
  */
 class Keyword {
   static const List<Keyword> values = const <Keyword>[
     const Keyword("assert"),
@@ skipping 187 matching lines @@
 /**
  * A state that has no outgoing transitions.
  */
 class LeafKeywordState extends KeywordState {
   LeafKeywordState(String syntax) : super(Keyword.keywords[syntax]);
 
   KeywordState next(int c) => null;
 
   String toString() => keyword.syntax;
 }