Save memory by not storing HTML to textarea undo

diff --git a/externals/jush b/externals/jush
index 2ab6fef7b478db03ddc7b6cb134b6fbd39626711..f7377bc3881c4e56c1addd6963bdf487ad947a16 160000 (submodule)
--- a/externals/jush
+++ b/externals/jush
@@ -1 +1 @@
-Subproject commit 2ab6fef7b478db03ddc7b6cb134b6fbd39626711
+Subproject commit f7377bc3881c4e56c1addd6963bdf487ad947a16