patch 9.0.1035: object members are not being marked as used

Problem:    Object members are not being marked as used, garbage collection
            may free them.
Solution:   Mark object members as used.  Fix reference counting.
diff --git a/src/vim9execute.c b/src/vim9execute.c
index b164502..3b142b8 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -3018,7 +3018,9 @@
 				       iptr->isn_arg.construct.construct_size);
 		tv->vval.v_object->obj_class =
 				       iptr->isn_arg.construct.construct_class;
+		++tv->vval.v_object->obj_class->class_refcount;
 		tv->vval.v_object->obj_refcount = 1;
+		object_created(tv->vval.v_object);
 		break;
 
 	    // execute Ex command line