Description:
------------
In the WeakReference documentation it says: "Weak references allow the programmer to retain a reference to an object which does not prevent the object from being destroyed. They are useful for implementing cache like structures."

And in the RFC it says:"The application might want to fetch the same serial number multiple times. Fetching the same product again and making a new object could have several problems. It might be slow and expensive."

However the current implementation means thats weak references don't prevent destruction when an object loses scope. This means that a cache service that persists objects in memory can't use the WeakReference object as hoped.

Ideally WeakReferences would prevent an object being destroyed until garbage collection is run.

For more information see https://www.drupal.org/project/drupal/issues/3190992#comment-14055154

Test script:
---------------
$obj = new stdClass;
$weakref = WeakReference::create($obj);
var_dump($weakref->get());
unset($obj);
var_dump($weakref->get());
gc_collect_cycles();
var_dump($weakref->get());

Expected result:
----------------
object(stdClass)#1 (0) {
}
object(stdClass)#1 (0) {
}
NULL

Actual result:
--------------
object(stdClass)#1 (0) {
}
NULL
NULL