title: Creating a file from a blob
body: <p>I'm in need of some javascript guru. I have this code:</p>
  
  <pre><code>handleImage(new File([blob], blob.name, {type: blob.type})).done(/* something */)
  </code></pre>
  
  <p>and </p>
  
  <pre><code>handleImage = function (image) {
          // create some fake form data
          var formData = new FormData();
          formData.append("attachment", image);
          formData.append("auto", true);
          formData.append("_csrf", "xxxxxxxxx");
  
          // post to the server.
          return $.ajax({
              url: "/some/url",
              data: formData,
              cache: false,
              contentType: false,
              processData: false,
              type: 'POST',
              error: function () {
                  console.log("error");
              }
          });
  </code></pre>
  
  <p>This works fine with Chrome and Firefox, but when using Safari (10.1.1), the server (java / spring mvc) receive in the <code>MultipartHttpServletRequest</code> an empty file for "attachment". So it seems to me that <code>new File([blob], blob.name, {type: blob.type})</code> is somehow failing. </p>
  
  <p>Any idea of what's wrong here?</p>