title: jQuery file upload in IE9 works only partly (with plugin jQuery File Upload)
body: <p>The central aims of this upload with this plugin:</p>
  
  <ul>
  <li>Upload up to 3 files (images) through 3 different input fields, without page reload.</li>
  <li>Do this together with other form data, that is not connected to a single file.</li>
  <li>Do it when creating and when editing a content item (in this case a category).</li>
  </ul>
  
  <p>I tested the IE9 in a VM with Windows 7. In Firefox, Chrome and Edge there is no problem.</p>
  
  <p>The problem in IE9 is:
  The upload does not work, when only 1 file is uploaded and this file is not the last file (so when I removed the third file input field, the upload through the second file input field worked).
  There is no problem, when at least 2 files are uploaded together.</p>
  
  <p>The libraries and plugins I use are:</p>
  
  <ul>
  <li>jquery 1.12.1 (also used versions down to 1.8.3-)</li>
  <li>jquery-ui 1.11.4 (also used a version 1.9.2)</li>
  <li>jQuery-File-Upload 9.12.1 (also used versions down to 8.1.0):
  
  <ul>
  <li>jquery.iframe-transport.js</li>
  <li>jquery.fileupload.js</li>
  </ul></li>
  </ul>
  
  <p>The configuration of the plugin:</p>
  
  <pre><code>file_upload = form.fileupload({replaceFileInput: false}, {
      //file_upload = form.fileupload({
          url: url,
          dataType: "json",
          singleFileUploads: false,
          autoUpload: false,
  
          add: function(e,data){
              uploadCategoryWithImage = true;
              filesList.push(data.files[0]);
              paramNames.push(data.paramName);
          },
  
          done: function(e, data) {
              switch (uploadContext) {
                  case 'update':
                      updateCategoryDone(node, form, data.result, data);
                      break;
                  case 'create':
                      storeNewCategoryDone(node, form, data.result)
                      break;
                  case 'createLevel1':
                      storeNewCategoryLevel1Done(form, data.result);
              }
          },
  
          fail: function( jqXHR, textStatus ) {
              console.log('prepareCategoryFileUploads fail [jqXHR, textStatus]: ', [jqXHR, textStatus]);
          }
  
      });
  </code></pre>
  
  <p>Used after click of submit button of form:</p>
  
  <pre><code>file_upload.fileupload('send', {files:filesList, paramName: paramNames});
  </code></pre>