Add uncommitted navigatorService file (#106)

examples/TestDriver/src/navigatorService.js

@@ -0,0 +1,24 @@
+// Used for testing compatibility with the "Navigation without navigation prop" pattern in React
+// Navigation. See https://reactnavigation.org/docs/en/navigating-without-navigation-prop.html.
+
+import { NavigationActions } from 'react-navigation';
+
+let _navigator;
+
+function setTopLevelNavigator(navigatorRef) {
+  _navigator = navigatorRef;
+}
+
+function navigate(routeName, params) {
+  _navigator.dispatch(
+    NavigationActions.navigate({
+      routeName,
+      params,
+    })
+  );
+}
+
+export default {
+  navigate,
+  setTopLevelNavigator,
+};