Instapaper is "a simple tool for saving web pages to read later on your iPhone, iPad, Android, computer, or Kindle." It adds div tags to the top and bottom of pages edited in VisualEditor.
See https://en.wikipedia.org/w/index.php?title=Major_Arcana_%28album%29&diff=589184449&oldid=589116581 for an example. It added this to the top and the bottom:
<div id="sendToInstapaperResults"></div>
Version: unspecified
Severity: minor
URL: https://en.wikipedia.org/w/index.php?title=Major_Arcana_%28album%29&diff=589184449&oldid=589116581