UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/48.0.2564.116 Safari/537.36

Steps to reproduce the problem:
0. keep DevTools open, look at the Network tab
1. go to http://output.jsbin.com/soyekid
2. now visit http://matteosistisette.com/test/stupidchrome/auth1/ajaxdata.php
3. When prompted for http authentication, enter these credentials:
  user:   auth1
  passwd: auth1
4. Go back to http://output.jsbin.com/soyekid

What is the expected behavior?
At step 1, you should (and do) see a blank page, and in Network tab a failed request to ajaxdata.php with response "401 Authorization required"

At step 4, however, the javascript request to ajaxdata.php should automatically send the credentials, because you are already authenticated, and should succeed, and hence you should see the dynamically loaded text "HERE's YOUR DATA" in the page

What went wrong?
Step 1 is as expected, but at step 4 the same happens as at step 1.

Did this work before? N/A 

Chrome version: 48.0.2564.116  Channel: n/a
OS Version: 
Flash Version: Shockwave Flash 20.0 r0

I seem to remember seeing a bug report about this very issue, but I couldn't find it. The search engine of this bug tracker sucks.