Add missing fields required for custom header use in v2.x.

See https://github.com/react-navigation/react-navigation/issues/4286

types/react-navigation/index.d.ts

@@ -607,6 +607,7 @@ export interface NavigationScene {
   isStale: boolean;
   key: string;
   route: NavigationRoute;
+  descriptor: NavigationDescriptor;
 }
 
 export interface NavigationTransitionProps {
@@ -1058,6 +1059,7 @@ export interface NavigationDescriptor<Params = NavigationParams> {
   key: string;
   state: NavigationLeafRoute<Params> | NavigationStateRoute<Params>;
   navigation: NavigationScreenProp<any>;
+  options: NavigationScreenOptions;
   getComponent: () => React.ComponentType;
 }
 

types/react-navigation/react-navigation-tests.tsx

@@ -1,5 +1,6 @@
 import * as React from 'react';
 import {
+    Text,
     TouchableOpacity,
     View,
     ViewStyle,
@@ -469,3 +470,22 @@ const BottomStack = createBottomTabNavigator({
         }
     }
 });
+
+const CustomHeaderStack = createStackNavigator({
+    Page1: { screen: Page1 },
+    Page2: { screen: Page2 }
+},
+{
+    navigationOptions: {
+        header: headerProps => {
+            const { scene } = headerProps;
+            const { options } = scene.descriptor;
+            const { title, headerStyle, headerTitleStyle } = options;
+            return (
+                <View style={headerStyle}>
+                    <Text style={headerTitleStyle}>{title}</Text>
+                </View>
+            );
+        }
+    }
+});