Tests how DOM.childNodeCountUpdated event works.
Node arrived with childNodeCount: 2
childCountUpdated: 3
childCountUpdated: 2
childCountUpdated: 1
childCountUpdated: 0
Tests how DOM.childNodeCountUpdated event works.
Node arrived with childNodeCount: 2
childCountUpdated: 3
childCountUpdated: 2
childCountUpdated: 1
childCountUpdated: 0