Use SumOfUs.org w/o its Javascript v1.1resigned1
Allows you to submit petitions on sumofus.org without disabling LibreJS or running non-free Javascript.
To use it just visit the website sumofus.org with LibreJS installed. Then, it will automatically recognize the site and start working.
This add-on assumes that you are running LibreJS and was tested on the latest version of GNU IceCat, a version of Firefox.
For more info about non-free Javascript and why it should be avoided:
https://www.gnu.org/philosophy/javascript-trap.en.html