Infinite loop upon creation of new XMLHttpRequest Object

The changes introduced in commit #8f1e7b940a476b0964483392a11005dc313dd3ff lead to an infinite loop between lines 33 and 27 by simply executing:
```javascript
new XMLHttpRequest();
```

 I suppose that this code will actually work if XHR object was first replaced by this library and after that replaced by yet another library but the way it is right now, the code simply doesn't work if this library is used stand-alone. Simply reverting the changes introduced by the above commit fixes the problems, but supposedly negates the effect intended by the original committer. Furthermore, the author forgot to replace the check in line 38
```javascript
if (bGecko && oXMLHttpRequest.wrapped) {
    cXMLHttpRequest.wrapped = window.XMLHttpRequest.wrapped;
}
```
because `oXMLHttpRequest` variable doesn't exist any more after the commit.