Scroll position jumps when highlighted text begins with an embed

[crsven]

Steps for Reproduction

1. Visit https://quilljs.com/playground/
2. Insert an image (this works with any embed)
3. Insert enough text to make sure the input will scroll
4. Select all text
5. Press (on a mac) Option + Shift + Left Arrow repeatedly

Expected behavior:
The scroll position does not change (or it only changes once to move to the start of the input).

Actual behavior:
Every time the keys are pressed, the scroll position jumps from the start to the end of the input.

Platforms:

Include browser, operating system and respective versions
macOS 10.15.7
Chrome 86.0.4240.80

Version:
1.3.6 & 1.3.7

[luin]

Should be fixed with #3840