Hah. Thanks. I was stopping by this thread again to post exactly that. I have to say that config option was not obvious. After scrolling through about:config and filtering only the modified list I still couldn't find it. I finally backed up prefs.js, toggled it, then pulled a diff.
And, I needed the config entry because I couldn't find any gui option to opt out of it on mobile.
And, I needed the config entry because I couldn't find any gui option to opt out of it on mobile.