Update httpBackend, check window.XMLHttpRequest

As per this issue: angular#5677

window.XMLHttpRequest is not always available in IE8 despite it not running in quirks mode, in which case Angular should be using the ActiveXObject instead. Just checking the browser version is taking too many shortcuts.

src/ng/httpBackend.js

@@ -3,7 +3,7 @@
 function createXhr(method) {
   // IE8 doesn't support PATCH method, but the ActiveX object does
   /* global ActiveXObject */
-  return (msie <= 8 && lowercase(method) === 'patch')
+  return ((msie <= 8 && lowercase(method) === 'patch') || isUndefined(window.XMLHttpRequest))
       ? new ActiveXObject('Microsoft.XMLHTTP')
       : new window.XMLHttpRequest();
 }