Use a basic filtered response for redirect navigations

Fixes whatwg/html#8740.

fetch.bs

@@ -5221,19 +5221,25 @@ these steps:
 
     <dl class=switch>
      <dt>"<code>error</code>"
-     <dd><p>Set <var>response</var> to a <a>network error</a>.
+     <dd>
+      <ol><li><p>Set <var>response</var> to a <a>network error</a>.</ol>
 
      <dt>"<code>manual</code>"
-     <dd><p>Set <var>response</var> to an <a>opaque-redirect filtered response</a> whose
-     <a for="filtered response">internal response</a> is <var>actualResponse</var>. If
-     <var>request</var>'s <a for=request>mode</a> is "<code>navigate</code>", then set
-     <var>fetchParams</var>'s <a for="fetch params">controller</a>'s <a
-     for="fetch controller">next manual redirect steps</a> to run <a>HTTP-redirect fetch</a> given
-     <var>fetchParams</var> and <var>response</var>.
+     <dd>
+      <ol>
+       <li><p>If <var>request</var>'s <a for=request>mode</a> is "<code>navigate</code>", then set
+       <var>fetchParams</var>'s <a for="fetch params">controller</a>'s
+       <a for="fetch controller">next manual redirect steps</a> to run <a>HTTP-redirect fetch</a>
+       given <var>fetchParams</var> and <var>response</var>.
+
+       <li><p>Otherwise, set <var>response</var> to an <a>opaque-redirect filtered response</a>
+       whose <a for="filtered response">internal response</a> is <var>actualResponse</var>.
+      </ol>
 
      <dt>"<code>follow</code>"
-     <dd><p>Set <var>response</var> to the result of running <a>HTTP-redirect fetch</a> given
-     <var>fetchParams</var> and <var>response</var>.
+     <dd>
+      <ol><li><p>Set <var>response</var> to the result of running <a>HTTP-redirect fetch</a> given
+      <var>fetchParams</var> and <var>response</var>.</ol>
     </dl>
     <!-- not resetting actualResponse since it's no longer used anyway -->
   </ol>