For JSON and script requests, set the scriptCharset before the url so…

… IE won't interpret it the wrong way; fixes #4855.

src/ajax.js

@@ -300,10 +300,10 @@ jQuery.extend({
 		if ( s.dataType === "script" && type === "GET" && remote ) {
 			var head = document.getElementsByTagName("head")[0] || document.documentElement;
 			var script = document.createElement("script");
-			script.src = s.url;
 			if ( s.scriptCharset ) {
 				script.charset = s.scriptCharset;
 			}
+			script.src = s.url;
 
 			// Handle Script loading
 			if ( !jsonp ) {