Chrome Version: 59, 60
OS: Windows 10

A repro case can be as simple as:

  while (1) alert('foo');

http://jsbin.com/jijefubopu/2/edit?js,output

There is no checkbox in the alert dialog, no option to stop showing these dialogs. The repro case can be as simple as a loop over alert() or confirm() -- I thought Chrome would show the "prevent additional..." checkbox in that case, but it never does.

In the wild: rocket26 dot xyz slash ar

It's possible to close the tab or navigate elsewhere, but to a normal user, a CRITICAL VIRUS WARNING OMGZ type dialog that can't be suppressed with OK/X/Esc  is a bad experience.