This article is from my exp. on turning on the configuration in FF after each release.The script window.close() won’t work after every release from mozilla. The reason i found was “dom.allow_scripts_to_close_windows” in all.js will be set to false by default. I was trying to do it in the hard way,i.e Go to the location of all.js and change it manually. But i found a another easy method we can call the about:config page in FireFox, we can toggle it easier. The following shows how to do it.
Enter about:config in location bar
Shows all the options available
Search for dom.allow_script
Highlight the entry dom.allow_scripts_to_close_windows and double click to toggle to true
Then write a simple script to check window.close()