UserAgent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/55.0.2883.87 Safari/537.36

Steps to reproduce the problem:
1. Go to a page that opens an alert box
2. Try to close or switch tabs

What is the expected behavior?

What went wrong?
Currently, you can't interact with anything other than an alert box when one is open, which can make it annoying to close some pages which spam you with alerts. 

Although there is a "Prevent this page from creating additional dialogs" option, you still need five clicks (OK, Prevent additional dialogs, OK, Close tab, Leave this page). By allowing the user to close the tab immediately, they could get rid of the page in only two clicks.

Also, switching tabs while a dialog is open can be useful for copying information from the dialog to another page or switching to another tab to find out what to put in a prompt dialog.

Did this work before? No 

Chrome version: 55.0.2883.87  Channel: stable
OS Version: 6.3
Flash Version: Shockwave Flash 24.0 r0