addChild
Inserts child into this tile's tiles at the position resolved by where — a no-op if this holder has no children list at all (tiles == null, i.e. it's a leaf tile). The mechanism behind AddTiles targeting this tile as groupingTileId. Does not itself mark this holder dirty or trigger a state update — callers (TilesManager.addTile/addTiles) do that explicitly right after.
Parameters
child
the already-built holder to insert.
where
where in the current children to insert it. Defaults to the end.