Provide RTL support in NavigationCardStack

Summary: Provide RTL support in NavigationCardStack

Reviewed By: fkgozali

Differential Revision: D3740172

fbshipit-source-id: 69466d24e148d0d81cb9f21c55f545abda46ac35

Libraries/CustomComponents/NavigationExperimental/NavigationHeaderBackButton.js

@@ -27,6 +27,7 @@ const React = require('react');
 const ReactNative = require('react-native');
 
 const {
+  I18nManager,
   Image,
   Platform,
   StyleSheet,
@@ -58,7 +59,8 @@ const styles = StyleSheet.create({
     height: 24,
     width: 24,
     margin: Platform.OS === 'ios' ? 10 : 16,
-    resizeMode: 'contain'
+    resizeMode: 'contain',
+    transform: [{scaleX: I18nManager.isRTL ? -1 : 1}],
   }
 });