It's opt-in at runtime. https://glandium.org/blog/?p=3899 https://glandium.org/blog/?p=3899 https://news.ycombinator.com/item?id=18465506 https://news.ycombinat

It's opt-in at runtime. https://glandium.org/blog/?p=3899 https://glandium.org/blog/?p=3899 https://news.ycombinator.com/item?id=18465506 https://news.ycombinator.com/item?id=18465506 And because that can cause problems when spawning third party applications from Firefox, there's another environment variable to opt-in in last nightly: https://bugzilla.mozilla.org/show_bug.cgi?id=1522780 https://bugzilla.mozilla.org/show_bug.cgi?id=1522780