fix scriptloading on old ie

lib/ace/lib/net.js

@@ -8,6 +8,8 @@
 define(function(require, exports, module) {
 "use strict";
 
+var useragent = require("ace/lib/useragent");
+
 exports.get = function (url, callback) {
     var xhr = exports.createXhr();
     xhr.open('GET', url, true);
@@ -56,7 +58,12 @@ exports.loadScript = function(path, callback) {
     s.src = path;
     head.appendChild(s);
 
-    s.onload = callback;
+    if (useragent.isOldIE)
+        s.onreadystatechange = function () {
+            this.readyState == 'loaded' && callback();
+        };
+    else
+        s.onload = callback;
 };
 
 });