listChildSubtrees( subtree, bottomRow ) {

		const results = [];
		const branchingFactor = getBoundsDivider( this.rootTile );
		for ( let i = 0; i < bottomRow.length; i ++ ) {

			const leafTile = bottomRow[ i ];
			if ( leafTile === undefined ) {

				continue;

			}
			for ( let j = 0; j < branchingFactor; j ++ ) {

				const index = i * branchingFactor + j;
				if ( this.getBit( subtree._childSubtreeAvailability, index ) ) {

					results.push( {
						tile: leafTile,
						childMortonIndex: index
					} );

				}

			}

		}
		return results;

	}
Determine what child subtrees exist and return a list of information.

@param {Object} subtree The subtree for looking up availability.
@param {Array} bottomRow The bottom row of tiles in a transcoded subtree.
@returns {[]} A list of identifiers for the child subtrees.
@private