[firebase_analytics] Fixes errors in firebase_analytics docs (flutter#1490)

Fixes navigation examples in firebase_analytics docs

Author: yadaniyil

packages/firebase_analytics/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.1.1+2
+
+* Fixed errors in code sample for `FirebaseAnalyticsObserver`.
+
 ## 2.1.1+1
 
 * Added hyperlinks to example app reference in README.md.

packages/firebase_analytics/lib/observer.dart

@@ -28,13 +28,13 @@ String defaultNameExtractor(RouteSettings settings) => settings.name;
 /// ```dart
 /// Navigator.pushNamed(context, '/contact/123');
 ///
-/// Navigator.push(context, MaterialPageRoute(
-///   settings: RouteSettings(name: '/contact/123',
-///   builder: ContactDetail(123)))),
+/// Navigator.push<void>(context, MaterialPageRoute(
+///   settings: RouteSettings(name: '/contact/123'),
+///   builder: (_) => ContactDetail(123)));
 ///
-/// Navigator.pushReplacement(context, MaterialPageRoute(
-///   settings: RouteSettings(name: '/contact/123',
-///   builder: ContactDetail(123)))),
+/// Navigator.pushReplacement<void>(context, MaterialPageRoute(
+///   settings: RouteSettings(name: '/contact/123'),
+///   builder: (_) => ContactDetail(123)));
 ///
 /// Navigator.pop(context);
 /// ```

packages/firebase_analytics/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for Google Analytics for Firebase, an app measuremen
   solution that provides insight on app usage and user engagement on Android and iOS.
 author: Flutter Team <[email protected]>
 homepage: https://github.com/flutter/plugins/tree/master/packages/firebase_analytics
-version: 2.1.1+1
+version: 2.1.1+2
 
 flutter:
   plugin: