[ASRangeController] We're already on main thread, remove blocks
Make data source read-only, clarify what's asynchronous
[ASDataController] Clean up some interfaces
[ASDataController] A little more cleanup
[ASDataController] Cleanup
[ASDataController] Restore some changes, exit more often
[ASDataController] Use item counts that we already have rather than requerying them
[ASDataController] Revert weakifications
[ASDataController] Add a mechanism to measure how much work we avoided
* make variable naming reflect ASEnvironmentTraitCollection vs ASTraitCollection
* move trait propagation to cell allocation instead of via a nested block
* move trait propagation when setting a displaynode's supernode instead of when adding a subnode
* fixed misspelling of "colection"
- _populateFromDataSourceWithSectionIndexSet doesn't accept a mutanle array but allocate one itself.
- Remove _populateFromEntireDataSourceWithMutableContexts.
- ASIndexedNodeContext executes its block, nil out the block and return the result.
- It is a container object that holds enough information to construct and measure a cell node
- All information is gathered on main thread. This allows ASDataController to capture the correct state of its data source before going to background.
