Add model test of CodegenWorldBuilder to compile_from_dill_test

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

Index: pkg/compiler/lib/src/universe/resolution_world_builder.dart
diff --git a/pkg/compiler/lib/src/universe/resolution_world_builder.dart b/pkg/compiler/lib/src/universe/resolution_world_builder.dart
index 4573a9106a8ff70516f6873488ac3cac4351b119..6f00df791d3e52167c07825b3aa5964c53536555 100644
--- a/pkg/compiler/lib/src/universe/resolution_world_builder.dart
+++ b/pkg/compiler/lib/src/universe/resolution_world_builder.dart
@@ -285,14 +285,22 @@ abstract class ResolutionWorldBuilderBase
   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 =