Add examples for "is closing" and "disowned"

Closes #4417.

Author: Yash-Handa

source

@@ -76323,6 +76323,25 @@ dictionary <dfn>DragEventInit</dfn> : <span>MouseEventInit</span> {
   from a document">removed from the document</span>, has no associated browsing context, since that
   browsing context was <span data-x="a browsing context is discarded">discarded</span>.</p>
 
+  <div class="example">
+   <p>The following example illustrates the various possibilities of a <span>browsing context</span>.
+   It can be <span>disowned</span>, <span>is closing</span>, neither, or both.</p>
+
+   <pre><code class="js">// Neither disowned nor is closing:
+const popup1 = window.open();
+
+// Disowned, but not is closing:
+const popup2 = window.open();
+popup2.opener = null;
+
+// Not disowned, but is closing:
+const popup3 = window.open();
+popup3.close();
+
+// Disowned, is closing:
+const popup4 = window.open();
+popup4.opener = null;
+popup4.close();</code></pre></div>
 
 
   <h4>Creating browsing contexts</h4>