Fix typo jobCallable -> callback

Author: syg

source

@@ -89626,7 +89626,7 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
 
   <ol>
    <li><p>Let <var>incumbent settings</var> be
-   <var>jobCallable</var>.[[HostDefined]].[[IncumbentSettings]]</p></li>
+   <var>callback</var>.[[HostDefined]].[[IncumbentSettings]]</p></li>
 
    <li><p>Let <var>script execution context</var> be
    <var>callback</var>.[[HostDefined]].[[ActiveScriptContext]].</li>