It should be possible to animate two CSS properties on an SVG with a CSS animation. This behaviour can be seen in Firefox but Safari (and Chrome) only render the last defined property change.
Chrome had the same issue and it has been confirmed as a bug there: https://code.google.com/p/chromium/issues/detail?id=319407 The workaround is to ensure a fill property is declared (although the is obviously still a bug).
Safari, Chrome, and Firefox all agree on rendering for this test case. I don't believe there is any remaining compatibility issue. (Tested with test case used in the Chromium bug).