splice() {
        const result = super.splice.apply(this, arguments);

        this.indicesDirty = true;
        this.calculateRenderablePositions();

        return result;
    }
Changes array contents by removing existing nodes and/or adding new nodes.

@param {number} start Start index.
@param {number} deleteCount Number of nodes to delete.
@param {TreeNode} ...nodes One or more nodes.
@return {array} Array of deleted elements.