Add model test of CodegenWorldBuilder to compile_from_dill_test

pkg/compiler/lib/src/enqueue.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.enqueue;
 
 import 'dart:collection' show Queue;
 
 import 'common/tasks.dart' show CompilerTask;
 import 'common/work.dart' show WorkItem;
 import 'common.dart';
 import 'common_elements.dart' show ElementEnvironment;
 import 'constants/values.dart';
 import 'compiler.dart' show Compiler;
 import 'options.dart';
 import 'elements/entities.dart';
 import 'elements/resolution_types.dart' show ResolutionTypedefType;
 import 'elements/types.dart';
+import 'js_backend/enqueuer.dart';
 import 'universe/world_builder.dart';
 import 'universe/use.dart'
     show
         ConstantUse,
         DynamicUse,
         StaticUse,
         StaticUseKind,
         TypeUse,
         TypeUseKind;
 import 'universe/world_impact.dart'
     show ImpactStrategy, ImpactUseCase, WorldImpact, WorldImpactVisitor;
 import 'util/enumset.dart';
 import 'util/util.dart' show Setlet;
 import 'world.dart' show ClosedWorld;
 
 class EnqueueTask extends CompilerTask {
   ResolutionEnqueuer _resolution;
+  CodegenEnqueuer codegenEnqueuerForTesting;
   final Compiler compiler;
 
   String get name => 'Enqueue';
 
   EnqueueTask(Compiler compiler)
       : this.compiler = compiler,
         super(compiler.measurer);
 
   // TODO(johnniwinther): Remove the need for this.
   bool get hasResolution => _resolution != null;
 
   // TODO(johnniwinther): Remove the need for this.
   ResolutionEnqueuer get resolution {
     assert(invariant(NO_LOCATION_SPANNABLE, _resolution != null,
         message: "ResolutionEnqueuer has not been created yet."));
     return _resolution;
   }
 
   ResolutionEnqueuer createResolutionEnqueuer() {
     return _resolution ??=
         compiler.backend.createResolutionEnqueuer(this, compiler);
   }
 
   Enqueuer createCodegenEnqueuer(ClosedWorld closedWorld) {
-    return compiler.backend.createCodegenEnqueuer(this, compiler, closedWorld);
+    return codegenEnqueuerForTesting =
+        compiler.backend.createCodegenEnqueuer(this, compiler, closedWorld);
   }
 }
 
 abstract class Enqueuer {
   WorldBuilder get worldBuilder;
 
   void open(ImpactStrategy impactStrategy, FunctionEntity mainMethod,
       Iterable<LibraryEntity> libraries);
   void close();
 
@@ skipping 521 matching lines @@
   final Entity element;
   final DeferredActionFunction action;
 
   DeferredAction(this.element, this.action);
 }
 
 /// Interface for creating work items for enqueued member entities.
 abstract class WorkItemBuilder {
   WorkItem createWorkItem(MemberEntity entity);
 }