Summary: This implements `EventHandlers` abstract class (aka "Events Guy") which encapsulates `eventDispatcher` and `instanceHandle` (and ownership of future `eventTarget`), all of this as part of existing {ShadowNode + Props + LayoutMetrics + LocalData + Descriptor + (and now) EventHandlers} infra. (We don't plan to add anything else to this model. Ever.)
Reviewed By: fkgozali
Differential Revision: D8053351
fbshipit-source-id: 1dd9ccbcbe5a2eb284b59ea351dc8beca645e8bf
Summary:
This fixes some build flavor:
```
error: destructor called on non-final 'facebook::react::Scheduler' that has virtual functions but non-virtual destructor [-Werror,-Wdelete-non-virtual-dtor]
```
Reviewed By: shergin
Differential Revision: D7958022
fbshipit-source-id: 6ff64bdaa221b5c6430a98244d40d6d3789ba937
Summary: ShadowTree is an abstraction around (commited) root shadow node and managing its lifecycle.
Reviewed By: mdvacca
Differential Revision: D7857049
fbshipit-source-id: 8d530e0366fc703e4aef4ec88dd8ea990dafaaf1
Summary: `RootShadowNode` is a dedicated class for managing the root node.
Reviewed By: mdvacca
Differential Revision: D7857050
fbshipit-source-id: f15f4b177f03cea4c0fd5a60d761ee2745319d77