Track the object element during init and remove it if the tech is dispos...

...ed before onReady. For #1339.

If dispose() was called before the SWF triggered onReady(), the placeholder div would be cleaned up but the actual object element would be left behind to mess things up in the future. Keep track of the object element during initialization and make sure it is removed if flash is unloaded early.
Sounds like an improvement to me. I'll update the PR.