Fix beforeunload prompt posting on /h/foo/submit.

The /submit frontend has special behavior to prevent the confirmation
prompt before navigation away onbeforeunload. This is to suppress the
prompt when navigating away via submitting the form as part of the
intended workflow. (otherwise pressing 'Post' looks like you're about
to lose your input.)

This has been extended to the /h/<sub>/submit pages also by correcting
the condition in the frontend logic.

files/templates/util/assetcache.html

@@ -22,7 +22,7 @@ set CACHE_VER = {
 	'js/emoji_modal.js': 297,
 	'js/formatting.js': 240,
 	'js/lottery.js': 256,
-	'js/marked.js': 274,
+	'js/marked.js': 275,
 	'js/submit.js': 263,
 	'js/userpage.js': 241,
 	'js/userpage_v.js': 245,