Tests that browser.Target.setAutoAttach() attaches early to window.open with empty urls.
Opened popup window
Attached to the popup window, waitingForDebugger=true
globalVar = undefined
Resumed popup window
Received console message in the popup: {
    method : Console.messageAdded
    params : {
        message : {
            column : 19
            level : log
            line : 4
            source : console-api
            text : 123
        }
    }
    sessionId : <string>
}
globalVar = 2020