Update JS

[malberts]

Tested manually on MW 1.37. Limited to checking if the upload button works when clicked, and if dragging files onto the button works (i.e. the files were uploaded successfully).

Special pages:

• /Special:BatchUpload
• /Special:BatchUpload/Foo

Parser functions:

• {{#batchupload:}}
• {{#batchupload:Foo|Bar|Baz}}

[malberts]

@JeroenDeDauw Tagging you since I cannot add a reviewer.

[JeroenDeDauw]