Pressing F4 for full screen editor freezes page

[kurzninja]

I haven't been able to figure out the exact cause, but in some of the editor windows, pressing F4 to try to enter full-screen editing causes the page to freeze up and eventually causes Chrome to say the page has stopped responding and ask to kill the tab. Reloading the tab brings the page back up, but trying to hit F4 on the same editor box repeats the problem.

Currently using Chrome 44.0.2403.52 beta-m (64-bit)

[madbernard]

I encountered this problem on Exercise 12. Because you have to reload the page, also leads to issue #83 where you have to re-run concatAll, so exercise 12 will work with the provided answer. Using Chrome 44.0.2403.155 m