Update Sizzle: use documentElement in focus selector. Fixes #13378.

diff --git a/src/sizzle b/src/sizzle
index cf19fa8dd6b7fda254bb3434f63d590845eaa7bf..578e0c6f403e5819eb7cff953990229c5593e0cf 160000 (submodule)
--- a/src/sizzle
+++ b/src/sizzle
@@ -1 +1 @@
-Subproject commit cf19fa8dd6b7fda254bb3434f63d590845eaa7bf
+Subproject commit 578e0c6f403e5819eb7cff953990229c5593e0cf