Remove package imports from itself.

pkg/front_end/lib/src/fasta/parser/top_level_parser.dart

 // Copyright (c) 2011, 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.parser.top_level_parser;
 
-import 'package:front_end/src/fasta/scanner/token.dart' show Token;
+import '../scanner/token.dart' show Token;
 
 import 'listener.dart' show Listener;
 
 import 'class_member_parser.dart' show ClassMemberParser;
 
 /// Parser which only parses top-level elements, but ignores their bodies.
 /// Use [Parser] to parse everything.
 class TopLevelParser extends ClassMemberParser {
   TopLevelParser(Listener listener, {bool asyncAwaitKeywordsEnabled: false})
       : super(listener, asyncAwaitKeywordsEnabled: asyncAwaitKeywordsEnabled);
 
   Token parseClassBody(Token token) => skipClassBody(token);
 }