Add @override annotations to flutter framework

diff --git a/packages/flutter_tools/lib/src/runner/flutter_command.dart b/packages/flutter_tools/lib/src/runner/flutter_command.dart
index b763f8e..d20c7b2 100644
--- a/packages/flutter_tools/lib/src/runner/flutter_command.dart
+++ b/packages/flutter_tools/lib/src/runner/flutter_command.dart

@@ -18,6 +18,7 @@
 typedef bool Validator();
 
 abstract class FlutterCommand extends Command {
+  @override
   FlutterCommandRunner get runner => super.runner;
 
   /// Whether this command needs to be run from the root of a project.
@@ -43,6 +44,7 @@
     applicationPackages ??= await ApplicationPackageStore.forConfigs(buildConfigurations);
   }
 
+  @override
   Future<int> run() {
     Stopwatch stopwatch = new Stopwatch()..start();
 

diff --git a/packages/flutter_tools/lib/src/runner/flutter_command_runner.dart b/packages/flutter_tools/lib/src/runner/flutter_command_runner.dart
index b89c9ec..630f01d 100644
--- a/packages/flutter_tools/lib/src/runner/flutter_command_runner.dart
+++ b/packages/flutter_tools/lib/src/runner/flutter_command_runner.dart

@@ -124,6 +124,7 @@
         defaultsTo: 'out/ios_sim_Release/');
   }
 
+  @override
   String get usageFooter {
     return 'Run "flutter -h -v" for verbose help output, including less commonly used options.\n'
            '\n'
@@ -165,6 +166,7 @@
     return '.';
   }
 
+  @override
   Future<dynamic> run(Iterable<String> args) {
     return super.run(args).then((dynamic result) {
       logger.flush();
@@ -172,6 +174,7 @@
     });
   }
 
+  @override
   Future<int> runCommand(ArgResults globalResults) {
     _globalResults = globalResults;