Many resource-fetching elements have support for the `referrerpolicy` attribute, which lets developers provide a keyword to influence the value of the `Referer` HTTP header that accompanies a request. The <link> element has support for this, so it is technically possible to preload a script with a developer-set referrer policy even though the <script> element does not have support for this attribute. This feature adds `referrerpolicy` support to the <script> element.
Docs: https://github.com/w3c/webappsec-referrer-policy/issues/96