* [ASVideoNode] Maintain playback position between visibility changes
* [ASVideoNode] Code style changes and moved the pause to be before caching the current playback time.
Otherwise the Travis CI build fails due to the documentation generation outputting to stderr instead of stdout for something that's actually not an error
* Measure performance for ASCellNode layout
* Address Adlai and Levi's feedback:
* Move to ASDisplayNode level
* Lock around setting/getting measurement options and results
* Record all measurement passes and report times as an array
* Only add relevant entries to the performanceMetrics dictionary
* Rebase
* Store sum and count instead of array
* Rename ScopeTimerDataPoint to ScopeTimerSum
* Address Levi's feedback
* Address Adlai's feedback
The previous code used either a `@property` with `assign, nonatomic` semantics, or a `__unsafe_unretained` (non-atomic) ivar pointer to an instance for `asyncdisplaykit_node`.
This commit changes those access so that they have the equivalent of `weak, atomic` semantics.
- `_ASDisplayView.mm`
- Removes the `_node` ivar that was qualified with `__unsafe_unretained`.
- Removes `@synthesize asyncdisplaykit_node = _node;`.
- All direct uses of `_node` were replaced with:
- Creates a strong reference via `ASDisplayNode *node = _asyncdisplaykit_node;`.
- `s/_node/node/`.
- These changes were made even if there's a single use of `_asyncdisplaykit_node` as a consistency / defensive measure so that anyone editing this code in the future does not accidentally use a `weak` reference twice.
- `ASDisplayNode.mm`
- Getters and setters for `asyncdisplaykit_node` were changed from `nonatomic, assign` semantics to the equivalent of `atomic, weak` semantics.
- `weak` semantics were implemented by using a `ASWeakProxy` object.
- `objc_setAssociatedObject` was changed from `OBJC_ASSOCIATION_ASSIGN` to `OBJC_ASSOCIATION_RETAIN` (the `atomic` version of retain).
- `ASDisplayNode+FrameworkPrivate.h`
- Changed the `@property` declarations for `asyncdisplaykit_node` from `nonatomic, assign` to `atomic, weak`.
- The actual getters and setters are implemented in `ASDisplayNode.mm`, which were changed accordingly.
