|nsISupportsWeakReference| is a factory interface which produces appropriate
instances of |nsIWeakReference|. Weak references in this scheme can only be
produced for objects that implement this interface.
@version 1.0
@see nsIWeakReference
@see nsSupportsWeakReference
|GetWeakReference| produces an appropriate instance of |nsIWeakReference|.
As with all good XPCOM `getters’, you own the resulting interface and should
manage it with an |nsCOMPtr|.
@see nsIWeakReference
@see nsWeakPtr
@see nsCOMPtr