or any other icon then there's no support for svg favicons in your browser.If you can see the green torus then the data-uri favicon is working.
If you can see the gold torus (Mmm doughnuts) then you are being clever and have the TamperMonkey script running.
If you can see an happy smileyface icon
in the addressfield/tab/tab-switcher of your browser then there is support for svg favicons,
however if you see a sad smileyface icon
or any other icon then there's no support for svg favicons in your browser.
Thanks to http://xn--dahlstrm-t4a.net/svg/favicon/favicon.html for idea for page.