Issue with multi-fields with <input name="Field[]" />

[tractorcow]

This isn't a common use case, but I've had to implement displaylogic support for a module with multiple repeated fields.

A form contains multiple groups of fields with <fieldlist class="displaylogic-holder">. Additional fields are added via clientside using javascript (fieldlist is cloned).

Proof of concept is up and working at https://github.com/isobar-nz/silverstripe-display-logic/commits/fix-rebuild, although I'm not sure this should be merged upstream.

[tractorcow]

I've also fixed an issue with IE11. It was erroring on the Object.entries() when looping.

[michalkleiner]

I'd be happy to look at a PR that adds support for array-style field names (FieldName[]), if we could also add some tests for that.