* [ASDisplayNode] Ensure that nil can never be returned from -measureWithSizeRange:
This can happen in rare cases when multiple relayouts occur while a transition is being measured.
* [ASDisplayNode] Use ternary operator style for nil check.
* Use childrenMap directly to prevent creating an NSArray in ASDK for ASLayoutSpec children
* Add locking for parent property in ASLayoutSpec
* Remove unnecessary import
* Add newline
* Add NSFastEnumeration to ASEnvironment and ASDisplayNode / ASLayoutSpec
* Change NSMutableArray initializer to arrayWithCapacity:
* Move ASLayoutSpec+Private.h into Private folder
Fixes building with Swift
* Remove lock for ASLayoutSpec parent
* Simplify applying layout transition in preparation for bigger layout transition API work
* Change from apply to complete in if layout transitions are involved and _applyLayout: to _setCalculatedLayout: for layout
* Change to applySubnodeInsertions and applySubnodeRemovals
* Change from completeTransition to commitTransition and flip logic around when to trampoline to the main thread for implicit hierarchy management
* More internal API improvements
* Fix merge conflicts
* Rename _layout to _calculatedLayout
* Fix ASTextNode's ascender to also include the line height specified by paragraph style in the attributed string.
* Merge conflict (original patch is for an old version)
* [ASEnvironmentTraitCollection] default user interface idiom to ASEnvironmentTraitCollection
UIUserInterfaceIdiomUnspecified is -1 so we were actually defaulting our trait collection to UIUserInterfaceIdiomPhone (which is 0).
* Fix a few places where we weren’t using the default method to create the base traits
[_ASHierarchyChangeSet] Oopsy daisy
[ASDataController] Tweak our update validation
[ASHierarchyChangeSet] Fix bugs
Finish up some stuff
[ASDataController] Put some stuff back
[ASChangeSetDataController] Always use changeset
[ASDataController] Put other stuff back
[_ASHierarchyChangeSet] Use fast enumeration
[_ASHierarchyChangeSet] Fix assertion format strings, return on fail so we don't crash in production
[ASDataController] Store data source item counts as vector rather than NSArray
[ASDataController] Build some tests for the update validation
[ASDataController] Fix issues with update validation
Get rid of new file
[ASDataController] Suppress changeset validation before initial reload
[ASDataController] Make invalid update log vs. exception publicly toggleable
