LibWeb: Move Window from DOM directory & namespace to HTML

The Window object is part of the HTML spec. :^)
https://html.spec.whatwg.org/multipage/window-object.html

Userland/Libraries/LibWeb/CSS/MediaList.cpp

@@ -65,7 +65,7 @@ void MediaList::delete_medium(String medium)
     // FIXME: If nothing was removed, then throw a NotFoundError exception.
 }
 
-bool MediaList::evaluate(DOM::Window const& window)
+bool MediaList::evaluate(HTML::Window const& window)
 {
     for (auto& media : m_media)
         media.evaluate(window);