UserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3133.0 Safari/537.36

Steps to reproduce the problem:
1. Using the below supplied JS which binds to window.blur if you loose focus on the tab, or follow any link that opens a new tab/window, you'll get stuck in a recursion of alert()s

2. Create an empty HTML page with just the below HTML, click the link, change tabs, open a new tab, click into another window...

3. Now you're stuck and either need to Ctrl+W, Alt+F4 or launch task manager to get out!

Example code (simplified):
<a href="#" target="_blank">Click me</a><script>window.onblur=function(){alert('Now you\'re stuck!');}</script>

What is the expected behavior?
See the prevent duplicate checkbox within the alert dialogue which would suppress the subsequent events form firing. 

What went wrong?
Stuck in an infinite loop of alert()s completely locking up all tabs within the Chrome window.

Did this work before? N/A 

Chrome version: 61.0.3133.0  Channel: canary
OS Version: 10.0
Flash Version: 

Test code:

<a href="#" target="_blank">Click me</a><script>window.onblur=function(){alert('Now you\'re stuck!');}</script>