Remove user override of window.open() in a sandbox

Fixes #5806.

Test: web-platform-tests/wpt#24974

Author: zcorpan

source

@@ -77811,23 +77811,7 @@ console.assert(iframeWindow.frameElement === null);
      <dt id="sandboxWindowOpen">If <var>sandboxingFlagSet</var> has the <span>sandboxed auxiliary
      navigation browsing context flag</span> set</dt>
 
-     <dd>
-      <p>The user agent may offer the user one of:
-
-      <ol>
-       <li><p>Set <var>chosen</var> to the result of <span>creating a new top-level browsing
-       context</span> and set <var>windowType</var> to "<code data-x="">new and
-       unrestricted</code>".</p></li>
-
-       <li><p>Set <var>chosen</var> to an existing <span>top-level browsing context</span>.</p>
-      </ol>
-
-      <p class="warning">If this case occurs, it means that an author has explicitly sandboxed the
-      document that is trying to open a link.</p>
-
-      <p class="note">If the user declines or the user agent doesn't offer the above, the variables
-      remain unchanged.</p>
-     </dd>
+     <dd><p>The user agent may report to a developer console that a popup has been blocked.</p></dd>
 
      <dt>If the user agent has been configured such that in this instance it will create a new
      browsing context</dt>