Remove self & document from IIFE arguments (#2258)

If self or document don't exist, they'll error instead of getting to the
checks.

Fixes #2257.

Author: mAAdhaTTah

plugins/keep-markup/prism-keep-markup.js

@@ -1,4 +1,4 @@
-(function (self, document) {
+(function () {
 
 	if (typeof self === 'undefined' || !self.Prism || !self.document || !document.createRange) {
 		return;
@@ -96,4 +96,4 @@
 			env.highlightedCode = env.element.innerHTML;
 		}
 	});
-}(self, document));
+}());