Split World usage into open, inference, and closed world.

pkg/compiler/lib/src/inferrer/inferrer_visitor.dart

 // Copyright (c) 2013, 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 inferrer_visitor;
 
 import 'dart:collection' show IterableMixin;
 
 import '../common.dart';
 import '../compiler.dart' show Compiler;
@@ skipping 932 matching lines @@
   bool isThisOrSuper(Node node) => node.isThis() || node.isSuper();
 
   Element get outermostElement {
     return analyzedElement.outermostEnclosingMemberOrTopLevel.implementation;
   }
 
   T _thisType;
   T get thisType {
     if (_thisType != null) return _thisType;
     ClassElement cls = outermostElement.enclosingClass;
-    ClassWorld classWorld = compiler.world;
+    ClassWorld classWorld = compiler.closedWorld;
     if (classWorld.isUsedAsMixin(cls)) {
       return _thisType = types.nonNullSubtype(cls);
     } else {
       return _thisType = types.nonNullSubclass(cls);
     }
   }
 
   T _superType;
   T get superType {
     if (_superType != null) return _superType;
@@ skipping 520 matching lines @@
     return type;
   }
 
   T visitCascade(Cascade node) {
     // Ignore the result of the cascade send and return the type of the cascade
     // receiver.
     visit(node.expression);
     return cascadeReceiverStack.removeLast();
   }
 }