After the latest `NoScript` update (https://noscript.net/?ver=2.6.9.29&prev=2.6.9.27), needed to allow `ajax.googleapis.com` to be able to do *anything* on the site (upvoting, commenting, etc).

Not sure though whether this is due to said update or a concurrent change on SX.

<sub>The above applies to Firefox (and NoScript) ... </sub>

----------

Further reading:

https://developers.google.com/speed/libraries/

> The Google **Hosted Libraries** is a stable, reliable, high-speed,
> globally available content distribution network for the most popular,
> open-source JavaScript libraries.
> 
> Google works directly with the key stakeholders for each library
> effort and accepts the latest versions as they are released. 
> 
> Libraries
> 
> To load a hosted library, copy and paste the HTML snippet for that
> library (shown below) in your web page. For instance, to load jQuery,
> embed the `<script
> src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>`
> snippet in your web page.

http://www.w3schools.com/jquery/jquery_get_started.asp

> One big advantage of using the hosted **jQuery** from Google or Microsoft:
> 
> Many users already have downloaded jQuery from Google or Microsoft
> when visiting another site. As a result, it will be loaded from cache
> when they visit your site, which leads to faster loading time. Also,
> most CDN's will make sure that once a user requests a file from it, it
> will be served from the server closest to them, which also leads to
> faster loading time.

http://encosia.com/3-reasons-why-you-should-let-google-host-jquery-for-you/

> (...) I urge you to use the Google HostedLibraries content delivery
> network to serve **jQuery** to your users directly from Google’s network
> of datacenters. Doing so has several advantages over hosting jQuery on
> your server(s): **decreased latency, increased parallelism,** and **better
> caching**.