more fixes for fasta analyzer integration

pkg/analyzer/test/generated/utilities_test.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.test.generated.utilities_test;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/standard_ast_factory.dart';
@@ skipping 43 matching lines @@
     }
     return super.isEqualNodes(first, second);
   }
 
   @override
   bool isEqualTokens(Token first, Token second) {
     if (expectTokensCopied && first != null && identical(first, second)) {
       fail('Failed to copy token: ${first.lexeme} (${first.offset})');
       return false;
     }
-    if (first is TokenWithComment) {
+    if (first?.precedingComments != null) {
       CommentToken comment = first.precedingComments;
       if (comment.parent != first) {
         fail('Failed to link the comment "$comment" with the token "$first".');
       }
     }
     return super.isEqualTokens(first, second);
   }
 }
 
 @reflectiveTest
@@ skipping 4314 matching lines @@
     tokenMap.put(key, value);
     expect(tokenMap.get(key), same(value));
   }
 }
 
 class _ExceptionThrowingVisitor extends SimpleAstVisitor {
   visitNullLiteral(NullLiteral node) {
     throw new ArgumentError('');
   }
 }