Bug: Backspace on RTL text unexpectedly scrolls up (Safari)

When editing multiple lines of RTL text in a Lexical editor that has a vertical scrollbar, pressing Backspace while the scroll position is not at the top unexpectedly causes the editor to scroll up.

This only happens in **RTL contexts** and specifically in **Safari**. It does not occur when editing LTR text or when using other browsers.

Lexical version: 0.34.0


## Steps To Reproduce

1. Create a Lexical editor with enough RTL content to overflow vertically (so a scrollbar appears).
2. Scroll down so the top of the editor is not visible.
3. Place the caret at the end of a line
4. Press Backspace to delete characters

## The current behavior

The editor jumps (scrolls up) every time Backspace is pressed in RTL content. This disrupts editing flow.

## The expected behavior

The editor should not change scroll position when pressing Backspace — it should only delete the character as expected.

## Impact of fix

Severity: High for RTL users — it makes editing long RTL documents very frustrating.
Frequency: Always reproducible with RTL text + scrollbar.
Affects: Any application using Lexical for RTL text editing (Arabic, Hebrew, Persian, Urdu, etc.).
Fixing this would significantly improve Lexical’s usability for RTL language users.