Steps to Reproduce:

1. Go to Wikipedia in Chrome.
2. Edit a page.
3. Enter many lines, e.g.

(1)
(2)
(3)
...
(98)
(99)
(100)

4. If you have a tall edit window, resize your browser so that it's about 25 lines.
5. Navigate so that your cursor is at the beginning of the line "(50)"
6. Press Enter

Expected result:
A blank line is entered. There are no other changes to the display.

Actual result.
A blank line is entered. The display jumps so that the newly added line is off the top of the window and not visible, and "(50)" is the first line visible.

Notes:

• I'm seeing this on Windows.
• It doesn't happen in Firefox, Edge, or IE, only in Chrome.
• It's been happening for a very long time so it's not due to a change in Chrome or in the wiki editor software.
• It also happens (and is even more annoying) when you copy/paste text ending in a newline rather than pressing enter.
• To skip the setup steps in the reproduction, you can go to https://en.wikipedia.org/w/index.php?title=User:Danbloch/sandbox2&action=edit