'They' as a singular pronoun is gramatically correct, you absolute fuckwaffle.
I've added some additional gender neutral replacements: his or her -> their man or woman -> person (s)he -> they Clicking the extension's button in Chrome will now also run the script. Since the script only runs on its own when the page first loads, some dynamically loading pages (such as facebook) will still show the unreplaced text. Clicking the button will scan the document as it is now and do all the replacements.
- (2018-05-15) poofballoon TM: I love it! It works great and is so needed. Thank you, creator <3