I'm getting this warning today when I try to use forum reactions. Also when I go to look at notifications it sends me to the profile page instead of to the little warning dialog.
I'm not seeing any warnings in the JS console in chrome, the only thing there is the adblock on autosave.
Nothing has changed on my system in weeks at this point.
I'm using chrome 43.0.2357.130 m with Windows 10.
Something I did notice while writing this post:
http://www.google-analytics.com/ga.js timed out for analytic tracking, then I got an XHR finished loading for analyticstick.json and notifications/inform and it appears like the Javascript is
mostly working now. But it's definitely taking a few moments after a page loads in for them to be fully active.

Edit:
Blocking google-analystics.com/ga.js seemed to fix the issue on my end, pages load snappy after I did that.