IE 11 is giving me a hard time...

I'm trying to send some binary data as a `Uint8Array` in a POST request, but `[Object object]` gets sent instead. In IE's dev tools, inspecting the request body reveals that the `Uint8Array` is being transformed incorrectly as `[Object object]`:

![screen shot 2016-03-15 at 9 31 20 am](https://cloud.githubusercontent.com/assets/440299/13793569/b991e3ea-eab4-11e5-9901-f9adee6f1beb.png)

I tried commenting out some code to see if the request will send the correct data, and it does. I commented out these lines:

```
if (utils.isArrayBuffer(requestData)) {
  requestData = new DataView(requestData);
}
```

https://github.com/mzabriskie/axios/blob/master/lib/adapters/xhr.js#L162

... and the resulting request sent binary data as expected:

<img width="463" alt="screen shot 2016-03-15 at 7 14 07 pm" src="https://cloud.githubusercontent.com/assets/440299/13800038/27c28680-eae2-11e5-9718-512fcc078cd7.png">

What is the purpose of the `new DataView()` call? What is happening that turns the binary data into the `[Object object]` string? Why does this break only in IE 11 (works in Chrome, Firefox, Edge)?

lib/adapters/xhr.js
'use strict';
var utils = require('./../utils');
var buildURL = require('./../helpers/buildURL');
var parseHeaders = require('./../helpers/parseHeaders');
var transformData = require('./../helpers/transformData');
var isURLSameOrigin = require('./../helpers/isURLSameOrigin');
var btoa = (typeof window !== 'undefined' && window.btoa) || require('./../helpers/btoa');
var settle = require('../helpers/settle');
module.exports = function xhrAdapter(resolve, reject, config) {
  var requestData = config.data;
  var requestHeaders = config.headers;
  if (utils.isFormData(requestData)) {
    delete requestHeaders['Content-Type']; 
  }
  var request = new XMLHttpRequest();
  var loadEvent = 'onreadystatechange';
  var xDomain = false;
  
  
  
  if (process.env.NODE_ENV !== 'test' && typeof window !== 'undefined' && window.XDomainRequest && !('withCredentials' in request) && !isURLSameOrigin(config.url)) {
    request = new window.XDomainRequest();