2699: spoof Navigator API
2699: spoof Navigator API

https://reviewboard.mozilla.org/r/147474/diff/4#index_header

I would have thought rounding DOWN to the nearest multiple of 10 would be better. Imagine being on FF61 and claiming to be 70 = might cause site issues
ghacksuserjs/ghacks-user.js,ghacksuserjs/ghacks-user.js