Disabling pull-to-refresh on FlatList causes all items to be re-created

## 🐛 Bug Report
When disabling pull-to-refresh in a `FlatList` by setting `onRefresh` to `undefined` every item in the list gets unmounted and recreated.

I looked into why this would be happening and it appears to be because of this code in `ScrollView`: https://github.com/facebook/react-native/blob/f741d338406d518c4f81fada723991b2938b8cc5/Libraries/Components/ScrollView/ScrollView.js#L1082-L1120

## To Reproduce
1. Add a `FlatList` with some data and `onRefresh` and `refreshing` set to valid values
2. Change `onRefresh` and `refreshing` to `undefined` 

## Expected Behavior
The item components already rendered should be reused

## Code Example
https://snack.expo.io/@maxschmeling/disrespectful-toffee

## Environment
```
  React Native Environment Info:
    System:
      OS: macOS 10.14.3
      CPU: (12) x64 Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
      Memory: 8.02 MB / 16.00 GB
      Shell: 5.3 - /bin/zsh
    Binaries:
      Node: 11.3.0 - ~/.nvm/versions/node/v11.3.0/bin/node
      Yarn: 1.13.0 - /usr/local/bin/yarn
      npm: 6.9.0 - ~/.nvm/versions/node/v11.3.0/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.1, macOS 10.14, tvOS 12.1, watchOS 5.1
    IDEs:
      Android Studio: 3.1 AI-173.4907809
      Xcode: 10.1/10B61 - /usr/bin/xcodebuild
    npmPackages:
      react: ^16.8.3 => 16.8.4 
      react-native: ^0.59.0 => 0.59.0 
    npmGlobalPackages:
      react-native-git-upgrade: 0.2.7
```


	const refreshControl = this.props.refreshControl;

	if (refreshControl) {
	if (Platform.OS === 'ios') {
	// On iOS the RefreshControl is a child of the ScrollView.
	// tvOS lacks native support for RefreshControl, so don't include it in that case
	return (
	// $FlowFixMe
	<ScrollViewClass {...props} ref={this._setScrollViewRef}>
	{Platform.isTV ? null : refreshControl}
	{contentContainer}
	</ScrollViewClass>
	);
	} else if (Platform.OS === 'android') {
	// On Android wrap the ScrollView with a AndroidSwipeRefreshLayout.
	// Since the ScrollView is wrapped add the style props to the
	// AndroidSwipeRefreshLayout and use flex: 1 for the ScrollView.
	// Note: we should only apply props.style on the wrapper
	// however, the ScrollView still needs the baseStyle to be scrollable

	return React.cloneElement(
	refreshControl,
	{style: props.style},
	<ScrollViewClass
	{...props}
	style={baseStyle}
	// $FlowFixMe
	ref={this._setScrollViewRef}>
	{contentContainer}
	</ScrollViewClass>,
	);
	}
	}
	return (
	// $FlowFixMe
	<ScrollViewClass {...props} ref={this._setScrollViewRef}>
	{contentContainer}
	</ScrollViewClass>
	);

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Disabling pull-to-refresh on FlatList causes all items to be re-created #23963

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Disabling pull-to-refresh on FlatList causes all items to be re-created #23963

Description

🐛 Bug Report

To Reproduce

Expected Behavior

Code Example

Environment

Metadata

Metadata

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