[url_launcher_platform_interface] use non static token for platform interface (flutter#2418)

Author: amirh

packages/url_launcher/url_launcher_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.5
+
+* Make the `PlatformInterface` `_token` non `const` (as `const` `Object`s are not unique).
+
 ## 1.0.4
 
 * Use the common PlatformInterface code from plugin_platform_interface.

packages/url_launcher/url_launcher_platform_interface/lib/url_launcher_platform_interface.dart

@@ -20,7 +20,7 @@ abstract class UrlLauncherPlatform extends PlatformInterface {
   /// Constructs a UrlLauncherPlatform.
   UrlLauncherPlatform() : super(token: _token);
 
-  static const Object _token = Object();
+  static final Object _token = Object();
 
   static UrlLauncherPlatform _instance = MethodChannelUrlLauncher();
 

packages/url_launcher/url_launcher_platform_interface/pubspec.yaml

@@ -3,13 +3,13 @@ description: A common platform interface for the url_launcher plugin.
 homepage: https://github.com/flutter/plugins/tree/master/packages/url_launcher/url_launcher_platform_interface
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 1.0.4
+version: 1.0.5
 
 dependencies:
   flutter:
     sdk: flutter
   meta: ^1.0.5
-  plugin_platform_interface: ^1.0.0
+  plugin_platform_interface: ^1.0.1
 
 dev_dependencies:
   flutter_test: