[BUGFIX] EM: Fix button "close window" after fulfilling dependencies

This fix opens the window in a sized window and changes the logic to
determine the correct function for closing the window.

Change-Id: Ie16d67284240a833e5bfae67d8b78eab808f9a79
Releases: 4.6
Resolves: #29788
Reviewed-on: http://review.typo3.org/5706
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers
Reviewed-by: Jigal van Hemert
Tested-by: Jigal van Hemert