Deopt popover remains across tabs if not closed prior

[mraleph]

Originally reported by @paulfryzel

What steps will reproduce the problem?

1. Load demo #1
2. Select the 'y' method in the left tray
3. Click on the deopt marker for CheckMaps (t12 CheckMaps t2 [0x2360e9d1])
4. Without closing the popover, select the 'graph' tab in the upper tray

The deopt popover (div.popover-content) remains across tabs and can no longer be hidden/removed without a page refresh. This can be repeated with numerous popover artifacts leftover.

https://code.google.com/p/irhydra/issues/detail?id=33