Popup invisible when clicking too fast while closing

[EtienneBruines]

Browser: Google Chrome 39

When clicking outside the popup to close it (so, anywhere within the document), and click the "show popup" button while the popup hasn't been fully closed (or has only just closed), the page does blur / go dark, but no popup is shown.

Reproduction:

• Go here: http://jsfiddle.net/m923boou/
• Click "show" to open the popup
• Now click anywhere to close it. While its being closed, hit "show" again.

The problem

The screen is grayed out, but there is no popup.