Fix onTransitionStart config not being invoked with keyboard aware navigator, and use prop over config when available

src/navigators/createKeyboardAwareNavigator.js

@@ -1,7 +1,7 @@
 import React from 'react';
 import { TextInput } from 'react-native';
 
-export default Navigator =>
+export default (Navigator, navigatorConfig) =>
   class KeyboardAwareNavigator extends React.Component {
     static router = Navigator.router;
     _previouslyFocusedTextInput = null;
@@ -49,7 +49,9 @@ export default Navigator =>
         }
       }
 
-      this.props.onTransitionStart &&
-        this.props.onTransitionStart(transitionProps, prevTransitionProps);
+      const onTransitionStart =
+        this.props.onTransitionStart || navigatorConfig.onTransitionStart;
+      onTransitionStart &&
+        onTransitionStart(transitionProps, prevTransitionProps);
     };
   };

src/navigators/createStackNavigator.js

@@ -28,7 +28,7 @@ function createStackNavigator(routeConfigMap, stackConfig = {}) {
   // Create a navigator with StackView as the view
   let Navigator = createNavigator(StackView, router, stackConfig);
   if (!disableKeyboardHandling) {
-    Navigator = createKeyboardAwareNavigator(Navigator);
+    Navigator = createKeyboardAwareNavigator(Navigator, stackConfig);
   }
 
   return Navigator;

src/views/StackView/StackView.js

@@ -24,10 +24,14 @@ class StackView extends React.Component {
         screenProps={this.props.screenProps}
         navigation={this.props.navigation}
         descriptors={this.props.descriptors}
-        onTransitionStart={this.props.navigationConfig.onTransitionStart}
+        onTransitionStart={
+          this.props.onTransitionStart ||
+          this.props.navigationConfig.onTransitionStart
+        }
         onTransitionEnd={(transition, lastTransition) => {
           const { navigationConfig, navigation } = this.props;
-          const { onTransitionEnd } = navigationConfig;
+          const onTransitionEnd =
+            this.props.onTransitionEnd || navigationConfig.onTransitionEnd;
           if (transition.navigation.state.isTransitioning) {
             navigation.dispatch(
               StackActions.completeTransition({