Summary:
(prior to the scroll metrics being set up, or prior to the view being scrolled to the right location).
I'm using a StackNavigator to push a FlatList secondary screen, and it was causing extraneous rendering (item X ->item 0 -> item X)
I've logged inside the render functions of my `renderItem` function, and verified that it no longer attempts to render item 0 anymore. And I've verified from the `VirtualizedList.state` no longer renders a `{first: 0, last: 0}`, but persistently stays at `{first: X, last: X}` from start until things stabilize.
Closes https://github.com/facebook/react-native/pull/14562
Reviewed By: bvaughn
Differential Revision: D5283771
Pulled By: sahrens
fbshipit-source-id: 0f70ac0b89922449bd20bfa69edbc8939eafdf1f
1ee602b655