* Minor refactors in ASCollectionView and its private cell classes
- `_ASCollectionReusableView` and `_ASCollectionViewCell` no longer expose getters for their collection element and cell node properties. This is to make sure that clients can only obtain elements from the visible map which is always the source of truth.
- Since the map can return `nil` for an element request, it's much safer to check and avoid adding/removing a nil pointer to an `NSArray`.
- Since we use a special way to check whether an object of kind of `_ASCollectionViewCell` or `_ASCollectionReusableView`, based on the assumption that these classes are subclass restricted, I added cast-or-return macros in the header files, closer to where the restrictions are declared.
* Add ASDynamicCastStrict
* Add element and node properties back to _ASCollectionReusableView and _ASCollectionViewCell
* Assert unexpected nil elements
* Always mark an element visible even if it is backed by an UIKit / non-_ASCollection* view
* Fix typo
* Remove unnecessary changes
* Dump mistakes
* Update CHANGELOG
* Can't track visibility of elements backed by non-_AS views
* Add a thread-safe layoutIfNeeded implementation to ASDisplayNode
* Trigger a layout pass when a display node enters preload state
- This ensures that all the subnodes have the correct size to preload their content.
* ASCollectionNode to trigger its initial data load when it enters preload state
* Minor change in _ASCollectionViewCell
* Layout sublayouts before dispatch to main for subclass hooks
* Update comments
* Don't wait until updates are committed when the collection node enters display state
* Same deal for table node
* Explain the layout trigger in ASDisplayNode
Resolves#3037
This is a do-over of c85aa11, with the following differences:
- Fixed `_ASTableViewCell` properties **always** being mutated to match corresponding `ASCellNode` passthrough properties, even when the hosted `ASCellNode` is currently `nil`. Now only inheriting passthrough properties when there’s an actual instance of `ASCellNode` to read them from.
- Corrected spelling of `ASCellNode`’s `separatorInset` property.
- Reverted `_ASCollectionViewCell` inheriting the hosted cell node’s `backgroundColor` & `clipsToBounds` properties. This seems to be surprising and unwanted behavior to some, as seen in #3053 and #3044.
- Moved passthrough of `UITableViewCell`’s `selectedBackgroundView` into `_ASTableViewCell`’s `-setNode:` for consistency.
