UserAgent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/49.0.2623.75 Safari/537.36

Steps to reproduce the problem:
1. open the attached html file
2. check the box that says "async"
3. middle-click the link

What is the expected behavior?
i expected it to open the link in a new background tab like how it does with the checkbox unchecked or when you middle-click any other ordinary link

What went wrong?
the browser switches to the newly opened tab

Did this work before? No 

Chrome version: 49.0.2623.75  Channel: stable
OS Version: 6.3
Flash Version: 

my popup blocker extension does some things asynchronously to either open the popup or block it  
when i have it enabled, middle-clicking a link that uses window.open causes the browser to switch to the newly opened tab  
i noticed it happening with the issue id links on the issue list page of this bug tracker

firefox gets it right and opens them in background tabs like it's supposed to but i don't use firefox
 

Deleted: test.html 431 bytes

test.html 431 bytes View Download