Fix access of muted errors flag in "report an error"

Changes "report an error" to check that the argument script is
a classic script before accessing its muted errors field, which is
not defined for other kinds of scripts.

Also applies the change to HostPromiseRejectionTracker.

Fixes whatwg#7501.

source

@@ -93240,9 +93240,10 @@ document.querySelector("button").addEventListener("click", bound);
     multiple lines.</p>
    </li>
 
-   <li><p>If <var>script</var>'s <span>muted errors</span> is true, then set <var>message</var> to
-   "<code data-x="">Script error.</code>", <var>urlString</var> to the empty string, <var>line</var>
-   and <var>col</var> to 0, and <var>errorValue</var> to null.</p></li>
+   <li><p>If <var>script</var> is a <span>classic script</span> and <var>script</var>'s <span>muted
+   errors</span> is true, then set <var>message</var> to "<code data-x="">Script error.</code>",
+   <var>urlString</var> to the empty string, <var>line</var> and <var>col</var> to 0, and
+   <var>errorValue</var> to null.</p></li>
 
    <li><p>Let <var>notHandled</var> be true.</p></li>
 
@@ -93450,7 +93451,8 @@ dictionary <dfn dictionary>PromiseRejectionEventInit</dfn> : <span>EventInit</sp
   <ol>
    <li><p>Let <var>script</var> be the <span>running script</span>.</p></li>
 
-   <li><p>If <var>script</var>'s <span>muted errors</span> is true, terminate these steps.</p></li>
+   <li><p>If <var>script</var> is a <span>classic script</span> and <var>script</var>'s <span>muted
+   errors</span> is true, terminate these steps.</p></li>
 
    <li><p>Let <var>settings object</var> be <var>script</var>'s <span>settings object</span>.</p>
    </li>