I'm getting this warning in Chrome when I try to show a dialog (alert()/confirm()/prompt()) from an iframe. Both domains belong to me.
A different origin subframe tried to create a JavaScript dialog. This is no longer allowed and was blocked. See https://www.chromestatus.com/feature/5148698084376576 for more details.
Could I resolve this via .htaccess or with an HTTP header or anything like that?