Closing alerts in Chrome occasionally fails

[heathkit]

Occasionally, when you try to close an alert on Linux you'll get the error:

{"code":-32603,"message":"Could not handle JavaScript dialog"}

This is due to a known issue (1500). With stress testing, I can reliably reproduce the problem on Linux, but not on OSX, so I'm assuming it's probably a Linux only thing.

When this is fixed, we'll also need to undo the horror that is #3933.