Tests frameStartedNavigating events when navigation is initiated by cdp command

Prepare
frameStartedNavigating {
    method : Page.frameStartedNavigating
    params : {
        frameId : <string>
        loaderId : <string 0>
        navigationType : differentDocument
        url : http://127.0.0.1:8000/inspector-protocol/resources/empty.html?window.open
    }
    sessionId : <string>
}
frameStartedNavigating {
    method : Page.frameStartedNavigating
    params : {
        frameId : <string>
        loaderId : <string 1>
        navigationType : differentDocument
        url : http://127.0.0.1:8000/inspector-protocol/resources/empty.html?link.click
    }
    sessionId : <string>
}