[TIMOB-589] db.close casuses crash

Blain -

I've attached the Resources directory for a simple test case. To reproduce:

1) open app
2) click button on first window (opens win1)
3) click button on second window (opens win2)
4) close window
5) close window (back on main window)

crash

The attributes that seem to cause the crash are:

1) having 3 windows on the stack where each window has a focus event listener that makes a database function call
2) the database function that is called calls db.close(). If you remove db.close() from the database function the crash does not occur
3) each window JS file includes the same db.js file