Follow-up: Selecting multiple images from library won't work

[indigoxela]

Description of the bug

Follow-up to Issue #440: Support "Multiple" attribute on file uploads.

Steps To Reproduce

1. Create an image field that allows multiple images
2. Make sure "Enable image browser" is clicked
3. Open a node form with that field
4. Open the image library ("Select existing file")
5. Select multiple images
6. Click on the insert button

Actual behavior

Although it was possible to select multiple images, only one image is actually inserted.

Inserting one by one still works fine.

Expected behavior

All selected images inserted to the field (of course, according to cardinality limits).

Additional information

• Backdrop CMS version: latest dev as of 3f77eaea0a0488c4f824de1f0bbf8e31041e4c44.

The selection part works, and that also respects limits, only the insert part doesn't work.
Unrelated file upload also works fine, BTW.

I guess, we have to tweak dialogCloseEvent, but don't have the time right now to dig deeper.