There is also make_ref_counted(), which does not call did_construct(),
so the method was not guaranteed to be run. Since there is only a single
user, and `WindowServer::Window` is a final class anyway (so there is no
need to separate the constructor and post-constructor phases), let's get
rid of this concept.
(The following commits reduce the opportunities to call
make_ref_counted, but still.)
2e6bb987a3