dillon1000/react

Consolidate hook events (#7472)

* Remove onBeforeMountComponent hook event

It is unnecessary.
We now pass the element as part of onInstantiateComponent, and it can't change before mounting.

* Remove onComponentHasMounted hook event

It is unused after #7410.

* Replace on(Begin|End)ReconcilerTimer hook events

We already have onBeforeUpdateComponent.
Let's just have on(Before?)(Mount|Update|Unmount)Component and stick with them.

This removes double event dispatches in some hot spots.

* Remove onComponentHasUpdated hook

The tests still pass so presumably it was not necessary.

* Add missing __DEV__ to TestUtils code

* Replace on(InstantiateComponent|SetParent) with onBeforeMountComponent

This lets us further consolidate hooks.
The parent ID is now passed as an argument to onBeforeMountComponent() with the element.

* Remove onMountRootComponent hook event

It is unnecessary now that we pass the parent ID to onBeforeMountComponent.

* Use parentDebugID = 0 both for roots and production

This removes some awkward branching.