<a href="https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1188121" rel="nofollow">https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1188121</a> appears to be the main tracking bug for this feature. It says &quot;... for developers&quot; in its summary.