Pull the 'keyword' property into Token.

pkg/analyzer/lib/src/dart/ast/token.dart

 // Copyright (c) 2014, 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 analyzer.src.dart.ast.token;
 
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 
 /**
@@ skipping 124 matching lines @@
         new DocumentationCommentToken(type, _value, offset);
     references.forEach((ref) => copy.references.add(ref.copy()));
     return copy;
   }
 }
 
 /**
  * A token representing a keyword in the language.
  */
 class KeywordToken extends SimpleToken {
-  /**
-   * The keyword being represented by this token.
-   */
+  @override
   final Keyword keyword;
 
   /**
    * Initialize a newly created token to represent the given [keyword] at the
    * given [offset].
    */
   KeywordToken(this.keyword, int offset) : super(TokenType.KEYWORD, offset);
 
   @override
   String get lexeme => keyword.syntax;
@@ skipping 88 matching lines @@
   @override
   bool get isOperator => type.isOperator;
 
   @override
   bool get isSynthetic => length == 0;
 
   @override
   bool get isUserDefinableOperator => type.isUserDefinableOperator;
 
   @override
+  Keyword get keyword => null;
+
+  @override
   int get length => lexeme.length;
 
   @override
   String get lexeme => type.lexeme;
 
   @override
   Token get next => _next;
 
   @override
   CommentToken get precedingComments => null;
@@ skipping 297 matching lines @@
   CommentToken get precedingComments => _precedingComment;
 
   void set precedingComments(CommentToken comment) {
     _precedingComment = comment;
     _setCommentParent(_precedingComment);
   }
 
   @override
   Token copy() => new TokenWithComment(type, offset, precedingComments);
 }