A step towards handling `new Object()` in compile_from_dill_test

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

Index: pkg/compiler/lib/src/universe/codegen_world_builder.dart
diff --git a/pkg/compiler/lib/src/universe/codegen_world_builder.dart b/pkg/compiler/lib/src/universe/codegen_world_builder.dart
index 6a7f84abd8b027687b6f27f74c0db22bc4557609..7fb0523f3d6d5e08321306c24bc982eae7295e30 100644
--- a/pkg/compiler/lib/src/universe/codegen_world_builder.dart
+++ b/pkg/compiler/lib/src/universe/codegen_world_builder.dart
@@ -616,7 +616,9 @@ class KernelCodegenWorldBuilder extends CodegenWorldBuilderImpl {
   @override
   void forEachInstanceField(
       ClassEntity cls, void f(ClassEntity declarer, FieldEntity field)) {
-    throw new UnimplementedError(
-        'KernelCodegenWorldBuilder.forEachInstanceField');
+    _elementEnvironment.forEachClassMember(cls,
+        (ClassEntity declarer, MemberEntity member) {
+      if (member.isField && member.isInstanceMember) f(declarer, member);
+    });
   }
 }