Add `blocking=render`

[Schweinepriester]

• Spec:
  • https://html.spec.whatwg.org/multipage/urls-and-fetching.html#blocking-attributes
  • Add the render-blocking mechanism and blocking=render attribute whatwg/html#7474
• Chrome:
  • https://chromestatus.com/feature/5452774595624960
  • Shipping in 105
• Firefox:
  • blocking="render" attribute on <link>, <script> and <style> mozilla/standards-positions#608
  • https://bugzilla.mozilla.org/show_bug.cgi?id=1751383
• Safari:
  • https://lists.webkit.org/pipermail/webkit-dev/2022-January/032088.html

[Schweinepriester]

Available via WF by now: https://caniuse.com/wf-blocking-render