Black icons have the wrong color in the Nested Content item picker

[kjac]

When a doctype has a black icon, it appears correctly in the list of items in Nested Content property editor. But in the item picker it's green-ish. It's probably some leftover from the grid editor item picker, which is reused styling wise for Nested Content.

It looks a bit inconsistent, specially when adding other icon colors to the items, which incidentally are displayed correctly.

I've got a fix for this, will submit a PR shortly.

[nul800sebastiaan]

Fixed in #3082