fix some issues found by strong mode

packages/flutter_tools/lib/src/commands/logs.dart

@@ -12,8 +12,8 @@ import 'flutter_command.dart';
 final Logger _logging = new Logger('sky_tools.logs');
 
 class LogsCommand extends FlutterCommand {
-  final name = 'logs';
-  final description = 'Show logs for running Sky apps.';
+  final String name = 'logs';
+  final String description = 'Show logs for running Sky apps.';
 
   LogsCommand() {
     argParser.addFlag('clear',

packages/flutter_tools/lib/src/device.dart

@@ -810,13 +810,15 @@ class AndroidDevice extends Device {
   }
 
   @override
-  Future<bool> startApp(AndroidApk apk) async {
+  Future<bool> startApp(ApplicationPackage app) async {
     // Android currently has to be started with startServer(...).
     assert(false);
     return false;
   }
 
-  Future<bool> stopApp(AndroidApk apk) async {
+  Future<bool> stopApp(ApplicationPackage app) async {
+    final AndroidApk apk = app;
+
     // Turn off reverse port forwarding
     runSync([adbPath, 'reverse', '--remove', 'tcp:$_serverPort']);
     // Stop the app

packages/flutter_tools/lib/src/test/remote_listener.dart

@@ -69,7 +69,7 @@ class RemoteListener {
       return;
     }
 
-    var declarer = new Declarer();
+    Declarer declarer = new Declarer();
     try {
       await runZoned(() => new Future.sync(main), zoneValues: {
         #test.declarer: declarer