Verify that layers are reported properly.
Layers for document scope: 
{
    name : implicit outer layer
    order : 5
    subLayers : [
        [0] : {
            name : base
            order : 1
            subLayers : [
                [0] : {
                    name : nested
                    order : 0
                }
            ]
        }
        [1] : {
            name : ext
            order : 2
        }
        [2] : {
            name : empty
            order : 3
        }
        [3] : {
            name : stylesheet
            order : 4
        }
    ]
}
Layers for shadow root scope: 
{
    name : implicit outer layer
    order : 2
    subLayers : [
        [0] : {
            name : shadow1
            order : 0
        }
        [1] : {
            name : shadow2
            order : 1
        }
    ]
}
Layers for empty shadow root scope: 
{
    name : implicit outer layer
    order : 0
}