Reverted commit D3278698

Summary:
= Breaking Change (for experimental features) =

Major API changes in  NavigationAnimatedView

= New prop `transition` for scene renderer

In NavigationAnimatedView, we should not use `position` as a proxy of the
transtion which happens whenever navigation state changes.

Because `position` does not change unless navigation index changes, it won't
be possible to build animations for actions that replace navigation state
without changing the index.

This diff introduces an abstract prop `transition` that is exposed to the scene
renderers.

= Replace `applyAnimation` with `configureTransition`.

Expose a new optional prop  `configureTransition` that allows people to configure
transitions easily.

For instance, to configure the transition, do this:

```
function configureTransition() {
  return {
    dutation: 123,
    easing: Easing.easeInOut,
  };
}

```
<NavigationAnimatedView configureTransition={configureTransition) />

```

Reviewed By: ericvicenti

Differential Revision: D3278698

fbshipit-source-id: b790b92e0fabb42488ff1135b1c37a3f0e9420f7

Libraries/NavigationExperimental/Reducer/NavigationScenesReducer.js

@@ -72,9 +72,6 @@ function NavigationScenesReducer(
   nextState: NavigationParentState,
   prevState: ?NavigationParentState,
 ): Array<NavigationScene> {
-  if (prevState === nextState) {
-    return scenes;
-  }
 
   const prevScenes = new Map();
   const freshScenes = new Map();