Use packages dart_parser, dart_scanner, and compiler_util.

pkg/compiler/lib/src/closure.dart

 // Copyright (c) 2012, 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 closureToClassMapper;
 
 import 'common/names.dart' show Identifiers;
 import 'common/resolution.dart' show ParsingContext, Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'common.dart';
 import 'compiler.dart' show Compiler;
 import 'constants/expressions.dart';
 import 'elements/resolution_types.dart';
 import 'elements/elements.dart';
 import 'elements/modelx.dart'
     show BaseFunctionElementX, ClassElementX, ElementX;
 import 'elements/visitor.dart' show ElementVisitor;
 import 'js_backend/js_backend.dart' show JavaScriptBackend;
 import 'resolution/tree_elements.dart' show TreeElements;
-import 'tokens/token.dart' show Token;
+import 'package:dart_scanner/dart_scanner.dart' show Token;
 import 'tree/tree.dart';
 import 'util/util.dart';
 import 'world.dart' show ClosedWorldRefiner;
 
 class ClosureTask extends CompilerTask {
   Map<Element, ClosureClassMap> _closureMappingCache =
       <Element, ClosureClassMap>{};
   Compiler compiler;
   ClosureTask(Compiler compiler)
       : compiler = compiler,
@@ skipping 1184 matching lines @@
 ///
 /// Move the below classes to a JS model eventually.
 ///
 abstract class JSEntity implements Entity {
   Entity get declaredEntity;
 }
 
 abstract class PrivatelyNamedJSEntity implements JSEntity {
   Entity get rootOfScope;
 }