rename fasta.Token.value --> lexeme

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 37 matching lines @@
     case 0xFEFF: // Zero width no-break space.
       return new NonAsciiWhitespaceToken(character, charOffset);
 
     default:
       return new NonAsciiIdentifierToken(character, charOffset);
   }
 }
 
 /// Common superclass for all error tokens.
 ///
-/// It's considered an implementation error to access [value] of an
+/// It's considered an implementation error to access [lexeme] of an
 /// [ErrorToken].
 abstract class ErrorToken extends Token {
   ErrorToken(int charOffset) : super(charOffset);
 
   PrecedenceInfo get info => BAD_INPUT_INFO;
 
-  String get value => throw assertionMessage;
+  String get lexeme => throw assertionMessage;
 
   String get stringValue => null;
 
   bool isIdentifier() => false;
 
   String get assertionMessage;
 
   ErrorKind get errorCode;
 
   int get character => null;
@@ skipping 121 matching lines @@
 ///
 /// In this case, brace means any of `(`, `{`, `[`, and `<`, parenthesis, curly
 /// brace, square brace, and angle brace, respectively.
 class UnmatchedToken extends ErrorToken {
   final BeginGroupToken begin;
 
   UnmatchedToken(BeginGroupToken begin)
       : this.begin = begin,
         super(begin.charOffset);
 
-  String toString() => "UnmatchedToken(${begin.value})";
+  String toString() => "UnmatchedToken(${begin.lexeme})";
 
   String get assertionMessage => "'$begin' isn't closed.";
 
   ErrorKind get errorCode => ErrorKind.UnmatchedToken;
 }