update fasta scanner to generate two types of comments

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 '../../scanner/token.dart';
 import 'token_constants.dart';
 
 class PrecedenceInfo implements TokenType {
@@ skipping 75 matching lines @@
     OPEN_CURLY_BRACKET_INFO,
     CLOSE_CURLY_BRACKET_INFO,
     INT_INFO,
     STRING_INFO,
     OPEN_SQUARE_BRACKET_INFO,
     CLOSE_SQUARE_BRACKET_INFO,
     DOUBLE_INFO,
     STRING_INTERPOLATION_INFO,
     STRING_INTERPOLATION_IDENTIFIER_INFO,
     HEXADECIMAL_INFO,
-    COMMENT_INFO,
+    SINGLE_LINE_COMMENT_INFO,
+    MULTI_LINE_COMMENT_INFO,
   ];
 
   @override
   bool get isAdditiveOperator => precedence == ADDITIVE_PRECEDENCE;
 
   @override
   bool get isAssignmentOperator => precedence == ASSIGNMENT_PRECEDENCE;
 
   @override
   bool get isAssociativeOperator =>
@@ skipping 223 matching lines @@
 const int POSTFIX_PRECEDENCE = 16;
 const PrecedenceInfo PERIOD_INFO =
     const PrecedenceInfo('.', 'PERIOD', POSTFIX_PRECEDENCE, PERIOD_TOKEN);
 const PrecedenceInfo QUESTION_PERIOD_INFO = const PrecedenceInfo(
     '?.', 'QUESTION_PERIOD', POSTFIX_PRECEDENCE, QUESTION_PERIOD_TOKEN,
     isOperator: true);
 
 const PrecedenceInfo KEYWORD_INFO =
     const PrecedenceInfo('keyword', 'KEYWORD', 0, KEYWORD_TOKEN);
 
-const PrecedenceInfo EOF_INFO =
-    const PrecedenceInfo('', 'EOF', 0, EOF_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', 'RECOVERY', 0, RECOVERY_TOKEN);
 
 const PrecedenceInfo IDENTIFIER_INFO =
     const PrecedenceInfo('identifier', 'STRING_INT', 0, IDENTIFIER_TOKEN);
 
 const PrecedenceInfo SCRIPT_INFO =
@@ skipping 32 matching lines @@
 const PrecedenceInfo STRING_INTERPOLATION_INFO = const PrecedenceInfo(
     '\${', 'STRING_INTERPOLATION_EXPRESSION', 0, STRING_INTERPOLATION_TOKEN);
 
 const PrecedenceInfo STRING_INTERPOLATION_IDENTIFIER_INFO =
     const PrecedenceInfo('\$', 'STRING_INTERPOLATION_IDENTIFIER', 0,
         STRING_INTERPOLATION_IDENTIFIER_TOKEN);
 
 const PrecedenceInfo HEXADECIMAL_INFO =
     const PrecedenceInfo('hexadecimal', 'HEXADECIMAL', 0, HEXADECIMAL_TOKEN);
 
-const PrecedenceInfo COMMENT_INFO =
-    const PrecedenceInfo('comment', 'COMMENT', 0, COMMENT_TOKEN);
+const PrecedenceInfo SINGLE_LINE_COMMENT_INFO =
+    const PrecedenceInfo('comment', 'SINGLE_LINE_COMMENT', 0, COMMENT_TOKEN);
+
+const PrecedenceInfo MULTI_LINE_COMMENT_INFO =
+    const PrecedenceInfo('comment', 'MULTI_LINE_COMMENT', 0, COMMENT_TOKEN);