Update media resource fetch to identify top-level self-fetch for blob URLs

Updates the resource fetch algorithm to calculate when a top-level self-fetch might be occurring for blob URLs, which is a case where blob URL partitioning would be bypassed.

See w3c/FileAPI#210 for details.

Corresponding PRs:

- whatwg/fetch#1879
- w3c/FileAPI#216

Author: recvfrom

source

@@ -38207,10 +38207,41 @@ interface <dfn interface>MediaError</dfn> {
     <p>Otherwise:</p>
 
     <ol>
+     <li><p>Let <var>isTopLevelSelfFetch</var> be false.</p></li>
+
+     <li><p>Let <var>settingsObject</var> be <span>media element</span>'s
+     <span>node document</span>'s <span>relevant settings object</span>.</p></li>
+
+     <li><p>Let <var>global</var> be the <span>media element</span>'s
+     <span>node document</span>'s <span>relevant global object</span>.</p></li>
+
+     <li>
+      <p>If all of the following conditions are true:</p>
+
+      <ul>
+       <li><p><var>global</var> is a <code>Window</code> object;</p></li>
+
+       <li><p><var>global</var>'s <span data-x="window navigable">navigable</span> is not
+       null;</p></li>
+
+       <li><p><var>global</var>'s <span data-x="window navigable">navigable</span>'s <span
+       data-x="nav-parent">parent</span> is null; and</p></li>
+
+       <li><p><var>settingsObject</var>'s <span
+       data-x="concept-environment-creation-url">creation URL</span> <span
+       data-x="concept-url-equals">equals</span> <span>URL record</span>,</p></li>
+      </ul>
+
+      <p>then set <var>isTopLevelSelfFetch</var> to true.</p>
+     </li>
+
+     <li><p>Let <var>stringOrEnvironment</var> be "<code data-x="">top-level-self-fetch</code>" if
+     <var>isTopLevelSelfFetch</var> is true; otherwise <var>settingsObject</var>.</p></li>
+
      <li><p>Let <var>object</var> be the result of <span data-x="blob-url-obtain-object">obtaining
      a blob object</span> using the <span>URL record</span>'s <span
-     data-x="concept-url-blob-entry">blob URL entry</span> and the <span>media element</span>'s
-     <span>node document</span>'s <span>relevant settings object</span>.</p></li>
+     data-x="concept-url-blob-entry">blob URL entry</span> and
+     <var>stringOrEnvironment</var>.</p></li>
 
      <li><p>If <var>object</var> is a <span>media provider object</span>, then set <var>mode</var>
      to <i>local</i>.</p></li>