Fix non-fetch-scheme navigation params initiator origin

Fixes whatwg#9517.

Also adds a note explaining the relationship between responseOrigin, response's URL, and response's location URL.

source

@@ -98193,11 +98193,18 @@ location.href = '#foo';</code></pre>
      data-x="policy-container-csp-list">CSP list</span>'s <span>CSP-derived sandboxing
      flags</span>.</p></li>
 
-     <li><p>Set <var>responseOrigin</var> to the result of <span>determining the origin</span>
-     given <var>response</var>'s <span data-x="concept-response-url">URL</span>,
-     <var>finalSandboxFlags</var>, and <var>entry</var>'s <span
-     data-x="she-document-state">document state</span>'s <span
-     data-x="document-state-initiator-origin">initiator origin</span>.</p></li>
+     <li>
+      <p>Set <var>responseOrigin</var> to the result of <span>determining the origin</span> given
+      <var>response</var>'s <span data-x="concept-response-url">URL</span>,
+      <var>finalSandboxFlags</var>, and <var>entry</var>'s <span
+      data-x="she-document-state">document state</span>'s <span
+      data-x="document-state-initiator-origin">initiator origin</span>.</p>
+
+      <p class="note">If <var>response</var> is a redirect, then <var>response</var>'s <span
+      data-x="concept-response-url">URL</span> will be the URL that led to the redirect to
+      <var>response</var>'s <span data-x="concept-response-location-url">location URL</span>; it
+      will not be the <span data-x="concept-response-location-url">location URL</span> itself.</p>
+     </li>
 
      <li>
       <p>If <var>navigable</var> is a <span>top-level traversable</span>, then:</p>
@@ -98408,7 +98415,7 @@ location.href = '#foo';</code></pre>
      transient activation</span></dd>
 
      <dt><span data-x="non-fetch-scheme-params-initiator-origin">initiator origin</span></dt>
-     <dd><span data-x="concept-url-origin">origin</span></dd>
+     <dd><var>responseOrigin</var></dd>
 
      <dt><span data-x="non-fetch-scheme-params-nav-timing-type">navigation timing type</span></dt>
      <dd><var>navTimingType</var></dd>