Browser extensions might attach event listeners to the DOM so the safest way to run this test is by running Chrome from command line:
google-chrome \
--enable-precise-memory-info \
--disable-extensions \
--disable-plugins \
--incognito \
http://localhost:8125
The above will run Chrome without extensions or plugins in incognito mode and open manual tests page.
Close any running Chrome instance beforehand because otherwise it will open a tab in currently opened Chrome (look for "Opening in existing browser session." in command line).
This is an editor instance. And there's some link.
This is another editor instance.
Unlike Editor 1 it doesn't have contenteditable=true initially. Check if it's editable after initializing the editors and back to non-editable after destroying them.