In IE8, the value of `typeof document.createElemen` is `object`, not `function` so this `isStandardBrowserEnv` returns `false`.

```
function isStandardBrowserEnv() {
  return (
    typeof window !== 'undefined' &&
    typeof document !== 'undefined' &&
    typeof document.createElement !== 'function'
  );
}
```

Because of this wrong determine, XDomainRequest is not working in IE8. I made a pull request for fix this, but failed to pass the CI.
lib/utils.js
if (thisArg && typeof val === 'function') {
      a[key] = bind(val, thisArg);
    } else {
      a[key] = val;
    }
  });
  return a;
}
module.exports = {
  isArray: isArray,
  isArrayBuffer: isArrayBuffer,
  isFormData: isFormData,
  isArrayBufferView: isArrayBufferView,
  isString: isString,
  isNumber: isNumber,
  isObject: isObject,
  isUndefined: isUndefined,
  isDate: isDate,
  isFile: isFile,
  isBlob: isBlob,
  isFunction: isFunction,
  isStream: isStream,
  isURLSearchParams: isURLSearchParams,
  isStandardBrowserEnv: isStandardBrowserEnv,
  forEach: forEach,
  merge: merge,
  extend: extend,
  trim: trim
};