UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36

Steps to reproduce the problem:
1. visit http://output.jsbin.com/badageb
2. Click on the link that reads "link to self"

This is a simplification. This could be a page in a website with a link to another page belonging to the same website

What is the expected behavior?
Since (despite the specs) you don't allow to set the prompt message for questionable "security" reasons, you should make sure that the message is correct.

1) When you are actually navigating to a different url or closing the tab/window, it should read "Do you want to leave this PAGE", not "site", because you are not necessarily leaving the site. The concept of "site" is not well defined, so we can't expect the browser to distinguish the case where you are leaving the site from the case where you are navigating to a page belonging to the same site. But we do can expect it to use a proper language and ask a question that always makes sense: whether you want to leave the PAGE

2) When you click a link to the same url of the current document, or when you focus the address bar and hit Enter (or re-type the full url of the current page, for that matter), the prompt should be the same that is used when you hit the Reload button: "Do you want to reload this page" (again, it should read "page", not "site").

What went wrong?
1) It says "site"

2) When you click a link to the same page itself, or  when you focus the address bar and hit Enter (or re-type the full url of the current page, for that matter), it still says "do you want to leave this site". Regardless of the site/page terminology, here the issue is that you are not leaving the page, you are reloading it, and it's trivial to detect it.

Did this work before? N/A 

Chrome version: 52.0.2743.82  Channel: n/a
OS Version: 
Flash Version: Shockwave Flash 22.0 r0