Create a special PrecedenceInfo for use during parser recovery.

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

 // Copyright (c) 2015, 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 fasta.scanner.precedence;
 
 import 'token_constants.dart';
 
 class PrecedenceInfo {
   final String value;
@@ skipping 211 matching lines @@
 const PrecedenceInfo PERIOD_INFO =
     const PrecedenceInfo('.', POSTFIX_PRECEDENCE, PERIOD_TOKEN);
 const PrecedenceInfo QUESTION_PERIOD_INFO =
     const PrecedenceInfo('?.', POSTFIX_PRECEDENCE, QUESTION_PERIOD_TOKEN);
 
 const PrecedenceInfo KEYWORD_INFO =
     const PrecedenceInfo('keyword', 0, KEYWORD_TOKEN);
 
 const PrecedenceInfo EOF_INFO = const PrecedenceInfo('EOF', 0, EOF_TOKEN);
 
+/// Precedence info used by synthetic tokens that are created during parser
+/// recovery (non-analyzer use case).
+const PrecedenceInfo RECOVERY_INFO =
+    const PrecedenceInfo('recovery', 0, RECOVERY_TOKEN);
+
 const PrecedenceInfo IDENTIFIER_INFO =
     const PrecedenceInfo('identifier', 0, IDENTIFIER_TOKEN);
 
 const PrecedenceInfo SCRIPT_INFO =
     const PrecedenceInfo('script', 0, SCRIPT_TOKEN);
 
 const PrecedenceInfo BAD_INPUT_INFO =
     const PrecedenceInfo('malformed input', 0, BAD_INPUT_TOKEN);
 
 const PrecedenceInfo OPEN_PAREN_INFO =
@@ skipping 26 matching lines @@
     const PrecedenceInfo('\${', 0, STRING_INTERPOLATION_TOKEN);
 
 const PrecedenceInfo STRING_INTERPOLATION_IDENTIFIER_INFO =
     const PrecedenceInfo('\$', 0, STRING_INTERPOLATION_IDENTIFIER_TOKEN);
 
 const PrecedenceInfo HEXADECIMAL_INFO =
     const PrecedenceInfo('hexadecimal', 0, HEXADECIMAL_TOKEN);
 
 const PrecedenceInfo COMMENT_INFO =
     const PrecedenceInfo('comment', 0, COMMENT_TOKEN);