[iOS] List block: Bullet overlaps placeholder in dark mode

[rachelmcr]

When adding a new list block in dark mode, the bullet overlaps the block placeholder:

This only happens in dark mode; I don't see any issue in light mode.

Tested on iPhone XS, iOS 13.1, WPiOS 13.3.0.20190926

[rachelmcr]

cc @etoledom

[etoledom]

Thank you for this report @rachelmcr

We were talking about this with @SergioEstevao , I didn't notice previously that this only happens on Dark Mode. That's a good lead!