Guard against missing FF options https://github.com/sitespeedio/sitespeed.io/issues/3072 (#1319)
Guard against missing FF options https://github.com/sitespeedio/sitespeed.io/issues/3072 (#1319)


tobli/browsertime,sitespeedio/browsertime,sitespeedio/browsertime,sitespeedio/browsertime,sitespeedio/browsertime