Issue 26148. Don't use a current token if it does not match - create a new synthetic.

pkg/analyzer/lib/src/generated/parser.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.generated.parser;
 
 import 'dart:collection';
 import "dart:math" as math;
 
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 3798 matching lines @@
         _reportErrorForCurrentToken(
             ParserErrorCode.UNEXPECTED_TOKEN, [_currentToken.lexeme]);
         _advance();
         return getAndAdvance();
       }
       _reportErrorForToken(ParserErrorCode.EXPECTED_TOKEN,
           _currentToken.previous, [type.lexeme]);
       return _createSyntheticToken(TokenType.SEMICOLON);
     }
     _reportErrorForCurrentToken(ParserErrorCode.EXPECTED_TOKEN, [type.lexeme]);
-    return _currentToken;
+    return _createSyntheticToken(type);
   }
 
   /**
    * If the current token has the type [TokenType.GT], return it after advancing
    * to the next token. Otherwise report an error and create a synthetic token.
    */
   Token _expectGt() {
     if (_matchesGt()) {
       return getAndAdvance();
     }
@@ skipping 6129 matching lines @@
    */
   const ParserErrorCode(String name, String message, [String correction])
       : super(name, message, correction);
 
   @override
   ErrorSeverity get errorSeverity => ErrorSeverity.ERROR;
 
   @override
   ErrorType get type => ErrorType.SYNTACTIC_ERROR;
 }