Support user class in compile_from_dill_test

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

Index: pkg/compiler/lib/src/universe/world_builder.dart
diff --git a/pkg/compiler/lib/src/universe/world_builder.dart b/pkg/compiler/lib/src/universe/world_builder.dart
index 4ebfc28c9cd1b3cd285762cbf1ac3721d56adfdf..f2ac141c4aefa6cb4d05dc9164b07392795023ce 100644
--- a/pkg/compiler/lib/src/universe/world_builder.dart
+++ b/pkg/compiler/lib/src/universe/world_builder.dart
@@ -20,12 +20,12 @@ import '../js_backend/backend.dart' show JavaScriptBackend;
 import '../js_backend/backend_usage.dart' show BackendUsageBuilder;
 import '../js_backend/interceptor_data.dart' show InterceptorDataBuilder;
 import '../js_backend/native_data.dart' show NativeBasicData, NativeDataBuilder;
+import '../kernel/element_map_impl.dart';
 import '../universe/class_set.dart';
 import '../universe/function_set.dart' show FunctionSetBuilder;
 import '../util/enumset.dart';
 import '../util/util.dart';
-import '../world.dart'
-    show World, ClosedWorld, ClosedWorldImpl, KernelClosedWorld, OpenWorld;
+import '../world.dart' show World, ClosedWorld, ClosedWorldImpl, OpenWorld;
 import 'selector.dart' show Selector;
 import 'use.dart'
     show