You can either use a current version of FireFox or Chromium/Google Chrome/Opera.
In order to run Metapolator in Chrome, Opera, or Chromium
# if the command for your chrome-browser is "chrome" $ chrome --js-flags="--harmony --harmony_proxies" # in a current *ubuntu linux that might be for chromium: $ chromium-browser --js-flags="--harmony --harmony_proxies" # and for chrome $ google-chrome-stable --js-flags="--harmony --harmony_proxies" # and for opera $ opera --js-flags="--harmony --harmony_proxies"