Firefox 57 / block Javascript per site
Solved it by developing an extension myself: https://addons.mozilla.org/en-US/firefox/addon/yesscript2/
uBlock Origin in "advanced mode" can block scripts with so-called dynamic filtering rules. It also distinguishes scripts between inline, 1st party and 3rd party. You can set up a default policy of blocking for all sites and selectively override it for specific sites.
Update:
uMatrix is even better and allows more fine-grained control