UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/62.0.3202.62 Safari/537.36

Steps to reproduce the problem:
1. Go to https://jsfiddle.net/1wwjtgwz/
2. Copy the text inside the box
3. Paste the text back to the box once or twice - second scrollbar should appear. 
4. Scroll down to the end of text.
5. Try to type something at the end of the text.

What is the expected behavior?
Outer container scroll position is not changed; caret is still visible to user. Moving caret up and down changes scroll position of both inner and outer container so the caret remains visible to user.

What went wrong?
Outer container scroll position is reset to 0. This will happen even when some text is deleted and iframe scrollbar disappeared.
Moving the caret up and down does not change scroll position of the outer container.

Did this work before? Yes 59 or 60 (not sure)

Does this work in other browsers? Yes

Chrome version: 62.0.3202.62  Channel: stable
OS Version: 
Flash Version: 

This behavior is encountered in Chrome 61, 62 and 63 beta. Also I noticed that everything is fine when the large text is not pasted, but added programmatically.