GC and jsdIStackFrame.script.functionObject.getWrappedValue();

In Firebug I had this line:
  var fn = frame.script.functionObject.getWrappedValue();
As far as I can tell this line prevented the script from being 
destroyed, even if I issue
  fn = null;
directly after it.  Is it possible?

Admittedly my evidence is indirect. With the line in, I see one script 
for every page reload.  Else not.

Ok, its even more indirect: I have a table that has an entry per script, 
filled when OnScriptCreated is called and removed when OnScriptDestroyed 
  is called.  Its very hard to find a bug caused by an object not being 
collected...

John.