fasta.Token implement analyzer.Token

pkg/front_end/lib/src/fasta/scanner/error_token.dart

 // Copyright (c) 2017, 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 licenset hat can be found in the LICENSE file.
 
 library dart_scanner.error_token;
 
 // TODO(ahe): ErrorKind doesn't belong in dart_parser. Move to compiler_util or
 // this package?
 import '../parser/error_kind.dart' show ErrorKind;
 
@@ skipping 61 matching lines @@
 
   ErrorKind get errorCode;
 
   int get character => null;
 
   String get start => null;
 
   int get endOffset => null;
 
   BeginGroupToken get begin => null;
+
+  @override
+  Token copyWithoutComments() {
+    throw 'unsupported operation';

[ahe, 2017/03/20 12:32:48]

import '../errors.dart';

internalError("Unsupported operation.", null, charOffset);

+  }
 }
 
 /// Represents an encoding error.
 class EncodingErrorToken extends ErrorToken {
   EncodingErrorToken(int charOffset) : super(charOffset);
 
   String toString() => "EncodingErrorToken()";
 
   String get assertionMessage => "Unable to decode bytes as UTF-8.";
 
@@ skipping 111 matching lines @@
   UnmatchedToken(BeginGroupToken begin)
       : this.begin = begin,
         super(begin.charOffset);
 
   String toString() => "UnmatchedToken(${begin.lexeme})";
 
   String get assertionMessage => "'$begin' isn't closed.";
 
   ErrorKind get errorCode => ErrorKind.UnmatchedToken;
 }