Show which user made what change to the page when viewing unpublished changes

Summary

When a user tries to close the editor and clicks on "Show changes" to view the unpublished changes to the page, he sees text highlighted in green/red/blue depending on what change was made. However, he's unable to tell who made what change exactly because there is no indication as to which user is responsible for what change.

Steps to Reproduce

1. Get User 1 and User 2 to edit a page and add some text into it.
2. User 1 clicks on "Close".
3. User 1 clicks on "Show changes" to view the unpublished changes.

Results

Everything is highlighted as stated in the legend, but I can't tell who made the change.

Suggestion

I want to be able to identify which user made what change exactly in the page.