Reduce use of elements/resolution_types in enqueuer.

pkg/compiler/lib/src/universe/world_builder.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 world_builder;
 
 import 'dart:collection';
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers;
@@ skipping 138 matching lines @@
 
 /// The [WorldBuilder] is an auxiliary class used in the process of computing
 /// the [ClosedWorld].
 // TODO(johnniwinther): Move common implementation to a [WorldBuilderBase] when
 // universes and worlds have been unified.
 abstract class WorldBuilder {
   /// All directly instantiated classes, that is, classes with a generative
   /// constructor that has been called directly and not only through a
   /// super-call.
   // TODO(johnniwinther): Improve semantic precision.
-  Iterable<ClassElement> get directlyInstantiatedClasses;
+  Iterable<ClassEntity> get directlyInstantiatedClasses;
 
   /// All types that are checked either through is, as or checked mode checks.
-  Iterable<ResolutionDartType> get isChecks;
+  Iterable<DartType> get isChecks;
+
+  /// All directly instantiated types, that is, the types of the directly
 
   /// Registers that [type] is checked in this world builder. The unaliased type
   /// is returned.
-  ResolutionDartType registerIsCheck(ResolutionDartType type);
+  void registerIsCheck(DartType type);
 
-  /// All directly instantiated types, that is, the types of the directly
   /// instantiated classes.
   // TODO(johnniwinther): Improve semantic precision.
-  Iterable<ResolutionDartType> get instantiatedTypes;
+  Iterable<InterfaceType> get instantiatedTypes;
 }