"Release Actions" has to check for current and not top-level browsing context (#1555)

Fixes #1540

Author: whimboo

index.html

@@ -8989,7 +8989,7 @@ <h3><dfn>Release Actions</dfn></h3>
 <p>The <a>remote end steps</a> are:
 
 <ol>
- <li><p>If the <a>current top-level browsing context</a> is <a>no longer open</a>,
+ <li><p>If the <a>current browsing context</a> is <a>no longer open</a>,
   return <a>error</a> with <a>error code</a> <a>no such window</a>.
 
  <li><p>Let <var>undo actions</var> be equal to the