Export StackViewTransitionConfigs (#4761)

* export StackViewTransitionConfigs

* Add changelogs

CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 ### Fixed
 - Error when building with haul: ref to pathToRegexp.compile(#4658).
 
+### Added
+- Export `StackViewTransitionConfigs` to allow you to extend default config in custom transition configs. [#4761](https://github.com/react-navigation/react-navigation/pull/4761)
+
 ## [2.9.1] - [2018-07-24](https://github.com/react-navigation/react-navigation/releases/tag/2.9.1)
 ### Fixed
 - Incorrect parameters passed to title offset calculation led to bug in header layout when no right component (https://github.com/react-navigation/react-navigation/issues/4754)

src/react-navigation.js

@@ -99,6 +99,9 @@ module.exports = {
   get StackViewCard() {
     return require('./views/StackView/StackViewCard').default;
   },
+  get StackViewTransitionConfigs() {
+    return require('./views/StackView/StackViewTransitionConfigs').default;
+  },
   get SafeAreaView() {
     return require('react-native-safe-area-view').default;
   },

src/views/StackView/StackViewTransitionConfigs.js

@@ -107,4 +107,8 @@ function getTransitionConfig(
 export default {
   defaultTransitionConfig,
   getTransitionConfig,
+  SlideFromRightIOS,
+  ModalSlideFromBottomIOS,
+  FadeInFromBottomAndroid,
+  FadeOutToBottomAndroid,
 };