Improve lang.stringRepeat function perfomance

lib/ace/lib/lang.js

@@ -36,7 +36,16 @@ exports.stringReverse = function(string) {
 };
 
 exports.stringRepeat = function (string, count) {
-     return new Array(count + 1).join(string);
+    var result = '';
+    while (count)
+    {
+        if (count & 1)
+                result += string;
+
+        if (count >>= 1)
+                string += string;
+    }
+    return result;
 };
 
 var trimBeginRegexp = /^\s\s*/;