Use module referrer policy for descendant fetches

Fixes w3c/webappsec-referrer-policy#111.

source

@@ -102628,8 +102628,15 @@ document.querySelector("button").addEventListener("click", bound);
 
    <dt><dfn data-x="concept-script-fetch-options-referrer-policy">referrer policy</dfn></dt>
 
-   <dd><p>The <span data-x="concept-request-referrer-policy">referrer policy</span> used for the
-   initial fetch and for fetching any imported modules</p></dd>
+   <dd>
+    <p>The <span data-x="concept-request-referrer-policy">referrer policy</span> used for the
+    initial fetch and for fetching any imported modules</p>
+
+    <p class="note">This policy can mutate after a <span>module script</span>'s <span
+    data-x="concept-response">response</span> is received, to be the <span>referrer policy</span>
+    <span data-x="parse-referrer-policy-header">parsed</span> from the <span
+    data-x="concept-response">response</span>, and used when fetching any module dependencies.</p>
+   </dd>
 
    <dt><dfn data-x="concept-script-fetch-options-render-blocking">render-blocking</dfn></dt>
 
@@ -103404,6 +103411,14 @@ document.querySelector("button").addEventListener("click", bound);
 
      <li><p>Let <var>module script</var> be null.</p></li>
 
+     <li><p>Let <var>referrerPolicy</var> be the result of <span
+     data-x="parse-referrer-policy-header">parsing the `<code>Referrer-Policy</code>` header</span>
+     given <var>response</var>. <ref spec="REFERRERPOLICY"></p></li>
+
+     <li><p>If <var>referrerPolicy</var> is not the empty string, set <var>options</var>'s <span
+     data-x="concept-script-fetch-options-referrer-policy">referrer policy</span> to
+     <var>referrerPolicy</var>.</p></li>
+
      <li><p>If <var>MIME type</var> is a <span>JavaScript MIME type</span> and <var>moduleType</var>
      is "<code data-x="">javascript</code>", then set <var>module script</var> to the result of
      <span>creating a JavaScript module script</span> given <var>source text</var>, <var>module map
@@ -105643,7 +105658,7 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
      <li><p>Set <var>settingsObject</var> to <var>referencingScript</var>'s <span>settings
      object</span>.</p></li>
 
-     <li><p>Set <var>fetchOptions</var> to the <span>descendant script fetch options</span> for
+     <li><p>Set <var>fetchOptions</var> to the new <span>descendant script fetch options</span> for
      <var>referencingScript</var>'s <span data-x="concept-script-script-fetch-options">fetch
      options</span>.</p></li>