[Bug] Remove dividers

[yoasif]

Steps to reproduce

1. Enable tab tray
2. Open some tabs
3. Open tab 3rd position from top
4. Open tab tray

Expected behavior

1. Divider is across the width of the screen or at least centered between items (not offset to one side)
2. The open tab highlight should be the same height across its length, not thicker on one end and thicker on the other.

Actual behavior

Divider seems to avoid tab thumbnail. Tab highlight looks weird because the height is inconsistent across its length.

UNITO-UNDERSCORE!2020-05-08-12-06-11!

Device information

• Android device: Moto G
• Fenix version: latest nightly

┆Issue is synchronized with this Jira Task

[LaurentiuApahideanSV]

I can confirm that this issue is reproducible using the latest version of Firefox Preview Nightly 200512 (Build #21330603).

Devices:
Huawei MediaPad M3 lite 10 (Android 7.0)

[topotropic]

Thanks for the feedback – I'd suggest we remove the dividers.

[liuche]

@boek would this be a good bug for @person808? Could start working in the tabs tray team too.

[darkwing]

@liuche Yes, @person808 would be an awesome choice! I think it's basically just reverting these two:

• For #10453: Use TabsTray API to set divider, avoiding related crashes. #10590
• For 10329: Implement tab tray divider #10325

[person808]

I assume point 2 doesn't apply anymore since the tab tray looks different now.

Edit: Nevermind, I misunderstood what point 2 was referring to

[LaurentiuApahideanSV]

Verified as fixed on Firefox Preview Nightly 200606 (Build #21610607) using a Huawei MediaPad M3 (Android 7.0).