LibWeb+LibJS: Move some code around to make CSS/Parser parse faster

This makes it possible to include fewer full definitions of things,
which makes the file about 30% faster to compile.

Userland/Libraries/LibWeb/HTML/TraversableNavigable.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <AK/QuickSort.h>
 #include <LibWeb/Bindings/MainThreadVM.h>
 #include <LibWeb/DOM/Document.h>
 #include <LibWeb/HTML/BrowsingContextGroup.h>