Token of an empty comment reference should end with EOF.

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 5015 matching lines @@
    * first character of the reference source. Return the comment reference that
    * was parsed, or `null` if no reference could be found.
    *
    *     commentReference ::=
    *         'new'? prefixedIdentifier
    */
   CommentReference _parseCommentReference(
       String referenceSource, int sourceOffset) {
     // TODO(brianwilkerson) The errors are not getting the right offset/length
     // and are being duplicated.
-    if (referenceSource.length == 0) {
-      Token syntheticToken =
-          new SyntheticStringToken(TokenType.IDENTIFIER, "", sourceOffset);
-      return new CommentReference(null, new SimpleIdentifier(syntheticToken));
-    }
     try {
       BooleanErrorListener listener = new BooleanErrorListener();
       Scanner scanner = new Scanner(
           null, new SubSequenceReader(referenceSource, sourceOffset), listener);
       scanner.setSourceStart(1, 1);
       Token firstToken = scanner.tokenize();
       if (listener.errorReported) {
         return null;
       }
+      if (firstToken.type == TokenType.EOF) {
+        Token syntheticToken =
+            new SyntheticStringToken(TokenType.IDENTIFIER, "", sourceOffset);
+        syntheticToken.setNext(firstToken);
+        return new CommentReference(null, new SimpleIdentifier(syntheticToken));
+      }
       Token newKeyword = null;
       if (_tokenMatchesKeyword(firstToken, Keyword.NEW)) {
         newKeyword = firstToken;
         firstToken = firstToken.next;
       }
       if (_tokenMatchesIdentifier(firstToken)) {
         Token secondToken = firstToken.next;
         Token thirdToken = secondToken.next;
         Token nextToken;
         Identifier identifier;
@@ skipping 5392 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;
 }