Using XmlHTTPRequest.open on WP8 raises a TypeError

Using the cordova-app-hello-world code on a WP8 device, connected to the device through weinre, trying to use XMLHTTPRequest like this:

var xhr = new XMLHttpRequest();
xhr.open('GET', 'js/index.js', true);
xhr.send();
console.log(xhr.responseText);

An error is raised at xhr.open: TypeError: Object doesn't support property or method 'addEventListener'

The same code on iOS runs through and shows me the content of index.js.

Changing the call to:

var xhr = new XMLHttpRequest();
xhr._url = 'js/index.js';
xhr.send();
console.log(xhr.responseText);

Returns the expected result.

I also noticed that XMLHttpRequest.prototype.open does not match the code in cordovalib\XHRHelper.cs:

function() {
var result;
callBeforeHooks(hookSite, this, arguments);
try {
result = func.apply(this, arguments);
} catch (e) {
callExceptHooks(hookSite, this, arguments, e);
throw e;
} finally {
callAfterHooks(hookSite, this, arguments, result);
}
return result;
}

GitHub repository with the code I used: https://github.com/gaqzi/cordova-wp8-xhr-test