Linux sandboxing improvements in Firefox 60
And if WebGl no longer works, try setting (in about:config)<p><pre><code>  security.sandbox.content.read_path_whitelist</code></pre>
to<p><pre><code>  /sys/class/drm/card0/device/config,/sys/class/drm/renderD128/device/config,/sys/class/drm/controlD64/device/config</code></pre>