https://zom.im/#faq state of expandable boxes starts cycling if doubleclicked

Google Chrome	54.0.2840.100 (Official Build) (64-bit)
Revision	ed651c97177b2ac846b27f62bb8efed6dac0f90b-refs/branch-heads/2840@{#833}
OS	Linux 
JavaScript	V8 5.4.500.41
Flash	23.0.0.207
User Agent	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.100 Safari/537.36
Command Line	/usr/bin/google-chrome-stable --wm-user-time-ms=258160 --flag-switches-begin --flag-switches-end --disable_transparent_visuals --window-depth=24 --x11-visual-id=32

Doubleclick on text of any expandable box in the FAQ.

Actual
The box starts expanding -> collapsing -> expanding -> ... until clicked once again.

Expected
The state of the box must transit only once.