Add model test of CodegenWorldBuilder to compile_from_dill_test

pkg/compiler/lib/src/universe/resolution_world_builder.dart

 // Copyright (c) 2017, 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.
 
 part of world_builder;
 
 abstract class ResolutionWorldBuilder implements WorldBuilder, OpenWorld {
   /// Set of all local functions in the program. Used by the mirror tracking
   /// system to find all live closure instances.
   Iterable<Local> get localFunctions;
@@ skipping 267 matching lines @@
   final Map<String, Map<Selector, SelectorConstraints>> _invokedNames =
       <String, Map<Selector, SelectorConstraints>>{};
   final Map<String, Map<Selector, SelectorConstraints>> _invokedGetters =
       <String, Map<Selector, SelectorConstraints>>{};
   final Map<String, Map<Selector, SelectorConstraints>> _invokedSetters =
       <String, Map<Selector, SelectorConstraints>>{};
 
   final Map<ClassEntity, _ClassUsage> _processedClasses =
       <ClassEntity, _ClassUsage>{};
 
+  Map<ClassEntity, _ClassUsage> get classUsageForTesting => _processedClasses;
+
   /// Map of registered usage of static members of live classes.
   final Map<Entity, _StaticMemberUsage> _staticMemberUsage =
       <Entity, _StaticMemberUsage>{};
 
+  Map<Entity, _StaticMemberUsage> get staticMemberUsageForTesting =>
+      _staticMemberUsage;
+
   /// Map of registered usage of instance members of live classes.
   final Map<MemberEntity, _MemberUsage> _instanceMemberUsage =
       <MemberEntity, _MemberUsage>{};
 
+  Map<MemberEntity, _MemberUsage> get instanceMemberUsageForTesting =>
+      _instanceMemberUsage;
+
   /// Map containing instance members of live classes that are not yet live
   /// themselves.
   final Map<String, Set<_MemberUsage>> _instanceMembersByName =
       <String, Set<_MemberUsage>>{};
 
   /// Map containing instance methods of live classes that are not yet
   /// closurized.
   final Map<String, Set<_MemberUsage>> _instanceFunctionsByName =
       <String, Set<_MemberUsage>>{};
 
@@ skipping 649 matching lines @@
         typesImplementedBySubclasses: typesImplementedBySubclasses,
         classHierarchyNodes: _classHierarchyNodes,
         classSets: _classSets);
   }
 
   @override
   void registerClass(ClassEntity cls) {
     throw new UnimplementedError('KernelResolutionWorldBuilder.registerClass');
   }
 }