The whitelist was introduced here:
<a href="https:&#x2F;&#x2F;hg.mozilla.org&#x2F;releases&#x2F;mozilla-aurora&#x2F;rev&#x2F;1e9694bbffaa" rel="nofollow">https:&#x2F;&#x2F;hg.mozilla.org&#x2F;releases&#x2F;mozilla-aurora&#x2F;rev&#x2F;1e9694bbf...</a>
<a href="https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1128227" rel="nofollow">https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=1128227</a><p>It&#x27;s described as &quot;TLS Intolerance fallback whitelist&quot;. It seems to allow RC4 and SSL3