Turns out there&#x27;s no good public API from Webkit that can let us do that easily.<p>We&#x27;re working on an alternative here <a href="https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1164067" rel="nofollow">https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1164067</a>