Multi file upload doesn't prepare destination directory

The function file_entity_add_upload_multiple_submit() (file_entity.pages.inc) doesn't prepare the upload directory. If the directory doesn't exist, it also doesn't make any attempt to create it. The result is that whenever you try to upload files, you get an error the file cannot be uploaded.

Adding a call to file_prepare_directory(dirname($destination)) just before file_unmanaged_move() fixes the problem (line 215 in the 2.0-unstable7 version).

* Running on OS X (MAMP)
* Media 7.x-2.0-unstable7, plupload 7.x-1.1, Media Multiselect from sandbox (git of today): http://drupal.org/sandbox/fangel/1652676

To reproduce:
* Create an Image field, use Media Multiselect as widget, unlimited cardinality, set (instance's) files directory to something non-existent
* Try to upload some files (using the plupload widget)
* Submit the widget

This will throw the error if the fix is not in place.

Note that the public files directory has all the required permissions, and Drupal is able to upload files directly to that directly without problems.