Steps to reproduce

1. Starting at URL: https://wordpress.com/post
2. Add content to a new post. Make sure it's enough content so the first line scrolls off the top of the screen.
3. Towards the end of the post, highlight some text
4. Click the hyperlink button in the toolbar and add a link.

What I expected

For the link to be added, but to still have the editor focused on the text I'm currently editing.

What happened instead

The editor jumped to the top of the post, and I had to scroll down to get back to the anchor text where I'd added the link.

Browser / OS version

Confirmed in latest versions of Firefox and Chrome on Mac OS X.

Screenshot / Video

Context / Source

Reported in the public forums in 871246-f