Propagate origin and URL list through the Request constructor

Tests: WPT service-workers/service-worker/navigation-headers.https.html and service-workers/service-worker/same-site-cookies.https.html.

Fixes #1321 and fixes #1335.

Co-authored-by: Anne van Kesteren <annevk@annevk.nl>

fetch.bs

@@ -6867,7 +6867,7 @@ constructor steps are:
 
   <dl>
    <dt><a for=request>URL</a>
-   <dd><var>request</var>'s <a for=request>current URL</a>.
+   <dd><var>request</var>'s <a for=request>URL</a>.
 
    <dt><a for=request>method</a>
    <dd><var>request</var>'s <a for=request>method</a>.
@@ -6888,7 +6888,10 @@ constructor steps are:
    <dd><var>request</var>'s <a for=request>priority</a>.
 
    <dt><a for=request>origin</a>
-   <dd>"<code>client</code>".
+   <dd><var>request</var>'s <a for=request>origin</a>. <span class=note>The propagation of the
+   <a for=/>origin</a> is only significant for navigation requests being handled by a service
+   worker. In this scenario a request can have an origin that is different from the current
+   client.</span>
 
    <dt><a for=request>referrer</a>
    <dd><var>request</var>'s <a for=request>referrer</a>.
@@ -6919,6 +6922,9 @@ constructor steps are:
 
    <dt><a for=request>history-navigation flag</a>
    <dd><var>request</var>'s <a for=request>history-navigation flag</a>.
+
+   <dt><a for=request>URL list</a>
+   <dd>A <a for=list>clone</a> of <var>request</var>'s <a for=request>URL list</a>.
   </dl>
 
  <li>
@@ -6933,10 +6939,17 @@ constructor steps are:
 
    <li><p>Unset <var>request</var>'s <a for=request>history-navigation flag</a>.
 
-   <li><p>Set <var>request</var>'s <a for=request>referrer</a> to
-   "<code>client</code>"
+   <li><p>Set <var>request</var>'s <a for=request>origin</a> to "<code>client</code>".
+
+   <li><p>Set <var>request</var>'s <a for=request>referrer</a> to "<code>client</code>".
 
    <li><p>Set <var>request</var>'s <a for=request>referrer policy</a> to the empty string.
+
+   <li><p>Set <var>request</var>'s <a for=request>URL</a> to <var>request</var>'s
+   <a for=request>current URL</a>.
+
+   <li><p>Set <var>request</var>'s <a for=request>URL list</a> to « <var>request</var>'s
+   <a for=request>URL</a> ».
   </ol>
 
   <p class=note>This is done to ensure that when a service worker "redirects" a request, e.g., from