Define the top-level origin of an environment settings object

This will provide the foundation for
whatwg/fetch#943 and other related changes
discussed in whatwg/fetch#904.

source

@@ -79269,8 +79269,8 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
   </ol>
 
   <p>To <dfn data-x="creating a new browsing context">create a new browsing context</dfn>, given
-  null or a <code>Document</code> object <var>creator</var> and <span>browsing context group</span>
-  <var>group</var>:</p>
+  null or a <code>Document</code> object <var>creator</var>, <span>browsing context group</span>
+  <var>group</var>, and an optional <var>intendedTopLevelOrigin</var>:</p>
 
   <!-- Note: Do not append the new browsing context to group as we might be creating a nested
        browsing context and not a top level browsing context -->
@@ -79315,8 +79315,12 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
     </ul>
    </li>
 
-   <li><p><span>Set up a window environment settings object</span> with <var>realm execution
-   context</var>, and let <var>settingsObject</var> be the result.</p></li>
+   <li><p>Let <var>topLevelOrigin</var> be <var>intendedTopLevelOrigin</var>, if present, otherwise
+   let <var>topLevelOrigin</var> be <var>origin</var>.
+
+   <li><p>Let <var>settingsObject</var> be the result of <span data-x="set up a window environment
+   settings object">setting up a window environment settings object</span> given <var>realm
+   execution context</var> and <var>topLevelOrigin</var>.</p></li>
 
    <li><p>Let <var>document</var> be a new <code>Document</code>, marked as an <span data-x="HTML
    documents">HTML document</span> in <span>quirks mode</span>, whose <span
@@ -79399,10 +79403,16 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
   given an element <var>element</var>:</p>
 
   <ol>
-   <li><p>Let <var>browsingContext</var> be the result of <span>creating a new browsing
-   context</span> with <var>element</var>'s <span>node document</span> and <var>element</var>'s
+   <li><p>Let <var>topLevelBrowsingContext</var> be <var>element</var>'s
    <span>node document</span>'s <span data-x="concept-document-bc">browsing context</span>'s
-   <span>top-level browsing context</span>'s <span data-x="tlbc group">group</span>.</p></li>
+   <span>top-level browsing context</span>.</p></li>
+
+   <li><p>Let <var>topLevelOrigin</var> be <var>topLevelBrowsingContext</var>'s
+   <span>active document</span>'s <span>origin</span>.</p></li>
+
+   <li><p>Let <var>browsingContext</var> be the result of <span>creating a new browsing
+   context</span> with <var>topLevelBrowsingContext</var>'s <span data-x="tlbc group">group</span>
+   and <var>topLevelOrigin</var>.</p></li>
 
    <li><p>Set <var>element</var>'s <span>nested browsing context</span> to
    <var>browsingContext</var>.</p></li>
@@ -81437,7 +81447,8 @@ interface <dfn>BarProp</dfn> {
   <h4>Script settings for <code>Window</code> objects</h4>
 
   <p>When the user agent is required to <dfn>set up a window environment settings object</dfn>,
-  given a <span>JavaScript execution context</span> <var>execution context</var> and an optional
+  given a <span>JavaScript execution context</span> <var>execution context</var>, a
+  <span>top-level origin</span> <var>top-level origin</var>, and an optional
   <span>environment</span> <var>reserved environment</var>, it must run the following steps:</p>
 
   <ol>
@@ -81517,6 +81528,13 @@ interface <dfn>BarProp</dfn> {
 
      </dd>
 
+     <dt>The <span>top-level origin</span></dt>
+     <dd>
+
+      <p>Return <var>top-level origin</var>.</p>
+
+     </dd>
+
      <dt>The <span>HTTPS state</span></dt>
      <dd>
 
@@ -85130,8 +85148,14 @@ interface <dfn>Location</dfn> { // but see also <a href="#the-location-interface
       </ul>
      </li>
 
+     <li><p>Let <var>topLevelOrigin</var> be <var>origin</var> if <var>browsingContext</var> is
+     <span>top-level browsing context</span>, otherwise let <var>topLevelOrigin</var> be
+     <var>browsingContext</var>'s <span>top-level browsing context</span>'s
+     <span>active document</span>'s <span>origin</span>.</p></li>
+
      <li><p><span>Set up a window environment settings object</span> with <var>realm execution
-     context</var> and <var>reservedEnvironment</var>, if present.</p></li>
+     context</var>, <var>topLevelOrigin</var>, and <var>reservedEnvironment</var>, if
+     present.</p></li>
     </ol>
    </li>
 
@@ -89305,6 +89329,15 @@ interface <dfn>ApplicationCache</dfn> : <span>EventTarget</span> {
 
    </dd>
 
+   <dt>A <dfn data-export="" data-dfn-for="environment settings object">top-level origin</dfn></dt>
+
+   <dd>
+
+    <p>The <span>origin</span> of the <span>top-level browsing context</span> at the time
+    this settings object was set up.</p>
+
+   </dd>
+
    <dt>An <dfn data-export="" data-dfn-for="environment settings object">HTTPS state</dfn></dt>
 
    <dd><p>An <span>HTTPS state value</span> representing the security properties of the network
@@ -91713,7 +91746,7 @@ import "https://example.com/foo/../module2.mjs";</code></pre>
 
   <ol>
    <li><p>Let <var>clusterKey</var> be the result of <span
-   data-x="obtain-agent-cluster-key">obtaining an agent cluster key</span> given
+   data-x="obtain-agent-cluster-key" data-export="">obtaining an agent cluster key</span> given
    <var>origin</var>.</p></li>
 
    <li><p>Let <var>agentCluster</var> be the result of <span
@@ -101859,6 +101892,18 @@ interface <dfn>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
 
      </dd>
 
+     <dt>The <span>top-level origin</span></dt>
+     <dd>
+
+      <p>Return <var>outside settings</var>'s <span>top-level origin</span> for a dedicated
+      worker.</p>
+
+      <p class="XXX">For shared and service workers this is still undefined and is being worked on,
+      since such workers could be associated with multiple <span data-x="top-level browsing
+      context">top-level browsing contexts</span>.</p>
+
+     </dd>
+
      <dt>The <span>HTTPS state</span></dt>
      <dd>