When getting a file via data URL from the zip extension, the "prefix" is always "data:application/octet-stream;base64,"

[snowboyz0825]

This doesn't seem like it should be a problem, but most extensions that handle dataURL require it to be the proper "prefix." You can work around it by splitting it off and joining it with the proper prefix, but it's annoying, clunky, and counter-intuitive.

This was the issue in #1601, but I feel we should fix it instead of closing it when a workaround is found.

The main issue would be breaking projects that already work around it, so we may have to do some trickery with legacy blocks