function didPopulateNode(parentNode, node)
        {
            if (node)
                this.revealTreeNode([parentNode, node]).then(callback);
            else
                callback(node);
        }
@this {WebInspector.HeapSnapshotConstructorsDataGrid}
@param {?WebInspector.HeapSnapshotGridNode} parentNode
@param {?WebInspector.HeapSnapshotGridNode} node