Language not spoofed for en-CA and en-UK
If a user installs an en-US tor-browser and then changes it to
English (Canada) or
English (United Kingdom) then neither the "locale spoofing prompt" is shown nor
Accept-Language is spoofed (e.g. for Canada it's
en-CA,en-US;q=0.7,en;q=0.3). The prompt is not shown because of https://searchfox.org/mozilla-central/source/toolkit/components/resistfingerprinting/RFPHelper.jsm#196. Besides, given
I'm not sure about the right solution, though. Should we show the spoofing prompt for these cases too? Or should we always spoof these two cases by default?