demo is broken with Epiphany browser

[jerch]

Currently the demo will not start up with the Epiphany browser (webkit based, gnome's default browser), because of the webgl addon being set as default.

Prolly linked to #3357, I think we need to find a more general conditional than isSafari for those webkit driven browsers, along with a more fine-grained version inspection (assuming newer webkit versions work already?)

[Tyriar]

That sucks, I don't think there was a way to detect this issue with the canvas going blank and Chrome includes AppleWebKit 😕