Introduce OpenWorld.

pkg/compiler/lib/src/resolution/resolution.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 dart2js.resolution;
 
 import 'dart:collection' show Queue;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers;
@@ skipping 46 matching lines @@
 import 'members.dart';
 import 'registry.dart';
 import 'resolution_result.dart';
 import 'signatures.dart';
 import 'tree_elements.dart';
 import 'typedefs.dart';
 
 class ResolverTask extends CompilerTask {
   final ConstantCompiler constantCompiler;
   final Resolution resolution;
-  final World world;
+  final OpenWorld world;
 
   ResolverTask(
       this.resolution, this.constantCompiler, this.world, Measurer measurer)
       : super(measurer);
 
   String get name => 'Resolver';
 
   DiagnosticReporter get reporter => resolution.reporter;
   Target get target => resolution.target;
   CoreTypes get coreTypes => resolution.coreTypes;
@@ skipping 933 matching lines @@
           element,
           new ResolutionRegistry(
               resolution.target, _ensureTreeElements(element)),
           defaultValuesError: defaultValuesError,
           createRealParameters: true));
     });
   }
 
   WorldImpact resolveTypedef(TypedefElementX element) {
     if (element.isResolved) return const ResolutionImpact();
-    world.allTypedefs.add(element);
+    world.registerTypedef(element);
     return _resolveTypeDeclaration(element, () {
       ResolutionRegistry registry = new ResolutionRegistry(
           resolution.target, _ensureTreeElements(element));
       return reporter.withCurrentElement(element, () {
         return measure(() {
           assert(element.resolutionState == STATE_NOT_STARTED);
           element.resolutionState = STATE_STARTED;
           Typedef node = element.parseNode(parsingContext);
           TypedefResolverVisitor visitor =
               new TypedefResolverVisitor(resolution, element, registry);
@@ skipping 91 matching lines @@
   TreeElements get treeElements {
     assert(invariant(this, _treeElements != null,
         message: "TreeElements have not been computed for $this."));
     return _treeElements;
   }
 
   void reuseElement() {
     _treeElements = null;
   }
 }