Introduce OpenWorld.

pkg/compiler/lib/src/use_unused_api.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.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
@@ skipping 229 matching lines @@
     ..addFirst(null, null, null)
     ..forEachLine(null)
     ..getFirstElementsInLine(null)
     ..forEachColumn(null, null);
   provider.getOffset(null, null);
 }
 
 usedByTests() {
   // TODO(ahe): We should try to avoid including API used only for tests. In
   // most cases, such API can be moved to a test library.
-  World world = null;
+  WorldImpl world = null;
   type_graph_inferrer.TypeGraphInferrer typeGraphInferrer = null;
   source_file_provider.SourceFileProvider sourceFileProvider = null;
   sourceFileProvider.getSourceFile(null);
   world.hasAnyUserDefinedGetter(null, null);
   world.subclassesOf(null);
   world.getClassHierarchyNode(null);
   world.getClassSet(null);
   world.haveAnyCommonSubtypes(null, null);
   typeGraphInferrer.getCallersOf(null);
   dart_types.Types.sorted(null);
@@ skipping 48 matching lines @@
   operators.UnaryOperator.fromKind(null);
   operators.BinaryOperator.fromKind(null);
   new semantic_visitor.BulkSendVisitor()..apply(null, null);
   new semantic_visitor.TraversalVisitor(null).apply(null, null);
   new semantic_visitor.BulkDeclarationVisitor().apply(null, null);
 }
 
 useDeferred([deferred.DeferredLoadTask task]) {
   task.dump();
 }