* [ASCollectionView] Initial pass at reducing double-sided animations
* [ASCollectionView] Always suppress animation during node size requery
* [ASCollectionView] Rejigger the invalidation logic to support animated size changes
* [ASCollectionView] Remove unused header
* [ASCollectionView] Change comment
* [ASDataController] Remove unused variable
* [ASCollectionView] When relayout animated due to cell size change, wait until next layout pass
* [ASCollectionView] Invalidate layout synchronously
* [ASCollectionView] Only read the layout object once
* [ASCollectionView] When size changes, wait for requery before layout
* [ASCollectionView] Sort of go back to using an empty update to handle node resizing
* [ASCollectionView] Remove unused constant
* [ASCollectionView] Address PR comments
* [ASCollectionView] Prevent nested [super performBatchUpdates:] calls
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