When the page clears notifications (URL changed, window closed, etc), the WebNotificationManager forwards that request to the client, but doesn't clean up its internal state. This could lead to notifications not being released when they should since the manager is still holding onto them.
<rdar://problem/10881167>
Created attachment 127478 [details] Patch
Committed r108566: <http://trac.webkit.org/changeset/108566>