Perform a microtask checkpoint only after a task

This further highlights the brokenness of "await a stable state". Tackling that fully is tracked by #2882.

Fixes #7845.

Author: annevk

source

@@ -106881,11 +106881,11 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
 
      <li><p>Set the <span>event loop</span>'s <span>currently running task</span> back to
      null.</p></li>
+
+     <li><p><span>Perform a microtask checkpoint</span>.</p></li>
     </ol>
    </li>
 
-   <li><p><span>Perform a microtask checkpoint</span>.</p></li>
-
    <li><p>Let <var>hasARenderingOpportunity</var> be false.</p></li>
 
    <li><p>Let <var>now</var> be the <span>unsafe shared current time</span>. <ref>HRT</ref></p></li>