title: Chrome WebKitBlobBuilder doesn't append data
body: <p>I'm implementing some file upload feature through ajax request. I'd like to be able to send multiple files in one ajax call, so i decided to use FormData.</p>
  
  <p>I tried to append my binary data string directly to the FormData (and it works), but the Content-Disposition doesn't have a filename attribute:
      Content-Disposition: form-data; name="file1"</p>
  
  <p>w3c says that i need to append a blob object to the formdata to have that attribute (or to be able to set it with the 3rd attribute of FormData.append())</p>
  
  <p>I wrote the following code:</p>
  
  <pre><code>function uploadAsBinary() {
      var xhr = new XMLHttpRequest();
      var fd = new FormData();
  
      window.BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder;
      var bb = new window.BlobBuilder();
      bb.append("this is my binary content");
      var blob = bb.getBlob("text/plain"); 
  
      fd.append("file1", blob, "file1");
  
      xhr.open("POST", "/mb/0/", false);
      xhr.send(fd);
  }
  </code></pre>
  
  <p>It works perfectly fine with firefox, but with google chrome (v16 and v17), the request payload is a formdata without content in it:</p>
  
  <pre><code>------WebKitFormBoundaryVkgESMAGtmPMlPZ7
  Content-Disposition: form-data; name="file1"; filename="file1"
  Content-Type: text/plain
  
  
  ------WebKitFormBoundaryVkgESMAGtmPMlPZ7--
  </code></pre>
  
  <p>I've also tried to fill the blob through an ArrayBuffer, same result. 
  I've been surfing the web for 2 days now, i've found no answer. I've found an open issue on android (http://code.google.com/p/android/issues/detail?id=22441) but it seems quite dead.</p>
  
  <p>Is this a real chrome issue ? Does someone have a clue about this, or should i open an issue on chromium tracker ?</p>
  
  <p>Thx for your help !</p>