Emojis in suggestion popup are completely black in Gnome when using light shell theme

[IgorKrupenja]

Steps:

1. Do a clean install of a distribution with Gnome DE (I used Manjaro 17.1.12 with GNOME 3.28).
2. Install ibus-uniemoji with all dependencies.
3. Install color emoji font if needed (I used Noto Emoji).
4. Open Gnome Tweaks and make sure that a light theme is selected in Appearance -> Themes -> Shell (e.g. Default Gnome theme will do).
5. Add UniEmoji layout in keyboard preferences.
6. Switch to UniEmoji layout and start typing.

Result:
Emoji suggestions are completely black unless you highlight them using arrow keys. Note how on this screenshot only the emoji highlighted in blue is displayed correctly:

This does not happen if you use dark shell theme:

[salty-horse]

UniEmoji doesn't control how they're displayed. This may be a GNOME bug with this theme, or an IBus bug.