Use entities in NativeResolutionEnqueuer and make it reusable for kernel

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

Index: pkg/compiler/lib/src/kernel/world_builder.dart
diff --git a/pkg/compiler/lib/src/kernel/world_builder.dart b/pkg/compiler/lib/src/kernel/world_builder.dart
index 80a67d597da80091303069cc782b9a58e8574de3..1356c0f4b3bfca4757e098f5ac9e797a423fe39a 100644
--- a/pkg/compiler/lib/src/kernel/world_builder.dart
+++ b/pkg/compiler/lib/src/kernel/world_builder.dart
@@ -23,9 +23,11 @@ import '../js_backend/backend_helpers.dart';
 import '../js_backend/constant_system_javascript.dart';
 import '../js_backend/no_such_method_registry.dart';
 import '../native/native.dart' as native;
+import '../native/resolver.dart';
 import 'element_adapter.dart';
 import 'elements.dart';
 
+part 'native_class_resolver.dart';
 part 'no_such_method_resolver.dart';
 
 /// World builder used for creating elements and types corresponding to Kernel
@@ -550,6 +552,11 @@ class KernelElementEnvironment implements ElementEnvironment {
   }
 
   @override
+  bool isSubtype(DartType a, DartType b) {
+    throw new UnimplementedError('KernelElementEnvironment.isSubtype');
+  }
+
+  @override
   ConstructorEntity lookupConstructor(ClassEntity cls, String name,
       {bool required: false}) {
     ConstructorEntity constructor = worldBuilder.lookupConstructor(cls, name);