Fix code demo in IE if Blockly is compiled harder.

Closure should not be used except within core.

demos/code/code.js

@@ -387,7 +387,7 @@ Code.init = function() {
   // TODO: Clean up the message files so this is done explicitly instead of
   // through this for-loop.
   for (var messageKey in MSG) {
-    if (goog.string.startsWith(messageKey, 'cat')) {
+    if (messageKey.indexOf('cat') == 0) {
       Blockly.Msg[messageKey.toUpperCase()] = MSG[messageKey];
     }
   }