typo

index.html

@@ -486,7 +486,7 @@ <h2><dfn>MediaDevices</dfn> Additions</h2>
                         with <var>source</var> and <var>mediaDevices</var>.</p>
                       </li>
                       <li>
-                        <p>Add <var>track</var> to <var>stream</var> track's set.</p>
+                        <p>Add <var>track</var> to <var>stream</var>'s track set.</p>
                       </li>
                       <li>
                         <p>[=Tie track source to MediaDevices=] with <var>source</var> and <var>mediaDevices</var>.</p>