Move closed world reasoning methods from ClassWorld to ClosedWorld.

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;
 import '../constants/constant_system.dart';
 import '../constants/expressions.dart';
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../resolution/operators.dart';
 import '../resolution/semantic_visitor.dart';
 import '../resolution/tree_elements.dart' show TreeElements;
 import '../tree/tree.dart';
 import '../types/constants.dart' show computeTypeMask;
 import '../types/types.dart' show TypeMask;
 import '../universe/call_structure.dart' show CallStructure;
 import '../universe/selector.dart' show Selector;
 import '../util/util.dart';
-import '../world.dart' show ClassWorld;
+import '../world.dart' show ClosedWorld;
 
 /**
  * The interface [InferrerVisitor] will use when working on types.
  */
 abstract class TypeSystem<T> {
   T get dynamicType;
   T get nullType;
   T get intType;
   T get uint31Type;
   T get uint32Type;
@@ skipping 908 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.closedWorld;
-    if (classWorld.isUsedAsMixin(cls)) {
+    ClosedWorld closedWorld = compiler.closedWorld;
+    if (closedWorld.isUsedAsMixin(cls)) {
       return _thisType = types.nonNullSubtype(cls);
     } else {
       return _thisType = types.nonNullSubclass(cls);
     }
   }
 
   T _superType;
   T get superType {
     if (_superType != null) return _superType;
     return _superType =
@@ skipping 519 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();
   }
 }