Move inline static styles at VirtualizedList to StyleSheet.create (#25501)

Summary:
I know StyleSheet.create doesn’t do anything special on react-native yet but it does on react-native-web and possibly other targets.

This small change is mainly so react-native-web don’t need to keep making this change on their code base when updating the rn version.

## Changelog

[Internal] [Changed] - Move inline static styles at VirtualizedList to StyleSheet.create
Pull Request resolved: https://github.com/facebook/react-native/pull/25501

Test Plan:
It’s basically the same code, just moved.
Also it’s the same change that it’s on react-native-web project: https://github.com/necolas/react-native-web/blob/45f94eb43daa3cb3d7fae0295877345a176c04c4/packages/react-native-web/src/vendor/react-native/VirtualizedList/index.js#L1650-L1654

Differential Revision: D16130700

Pulled By: cpojer

fbshipit-source-id: 20639e2e1a795ff4819c16af15569bf12759a62c

Libraries/Lists/VirtualizedList.js

@@ -1849,10 +1849,10 @@ class CellRenderer extends React.Component<
     );
     const cellStyle = inversionStyle
       ? horizontal
-        ? [{flexDirection: 'row-reverse'}, inversionStyle]
-        : [{flexDirection: 'column-reverse'}, inversionStyle]
+        ? [styles.rowReverse, inversionStyle]
+        : [styles.columnReverse, inversionStyle]
       : horizontal
-      ? [{flexDirection: 'row'}, inversionStyle]
+      ? [styles.row, inversionStyle]
       : inversionStyle;
     if (!CellRendererComponent) {
       return (
@@ -1907,6 +1907,15 @@ const styles = StyleSheet.create({
   horizontallyInverted: {
     transform: [{scaleX: -1}],
   },
+  row: {
+    flexDirection: 'row',
+  },
+  rowReverse: {
+    flexDirection: 'row-reverse',
+  },
+  columnReverse: {
+    flexDirection: 'column-reverse',
+  },
   debug: {
     flex: 1,
   },