Snackbars have wrong anchoring / padding

[Mugurell]

Steps to reproduce

1. Open wikipedia.org (just because it has it's own search box that would trigger the keyboard to show)
2. Long click on a link to open it in a new tab
3. Tap the website's input box to see the keyboard

Expected behavior

• The keyboard is shown above the toolbar (Y axis), with a small padding between them
• The keyboard is shown above the keyboard (Y axis), with a small padding between them

Actual behavior

• The keyboard is shown on top of the toolbar (Z axis)
• The keyboard is shown above the keyboard (Y axis), with a hude padding between them (the keyboard height?)

Other details

The bug related to the toolbar anchoring seems like an old issue.
The bug related to the keyboard anchoring seems to have been introduced by #3680

Recording of the issue: https://github.com/user-attachments/assets/3bf0a18d-88b3-414f-9899-8c35f1a50507

[Mugurell]

This was opened as a followup to https://bugzilla.mozilla.org/show_bug.cgi?id=1933481#c4