Add @override annotation to known overriden methods

sky/sdk/example/fitness/lib/home.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'package:sky/painting/text_style.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/drawer.dart';
 import 'package:sky/widgets/drawer_header.dart';
 import 'package:sky/widgets/floating_action_button.dart';
 import 'package:sky/widgets/icon.dart';
@@ skipping 17 matching lines @@
     // if (debug)
     //   new Timer(new Duration(seconds: 1), dumpState);
     _drawerController = new DrawerController(_handleDrawerStatusChanged);
   }
 
   Navigator navigator;
   List<Measurement> userData;
 
   FitnessMode _fitnessMode = FitnessMode.measure;
 
+  @override
   void syncFields(HomeFragment source) {
     navigator = source.navigator;
     userData = source.userData;
   }
 
   bool _isShowingSnackBar = false;
   bool _isRunning = false;
 
   DrawerController _drawerController;
   bool _drawerShowing = false;
@@ skipping 139 matching lines @@
         return new FloatingActionButton(
           child: new Icon(
             type: _isRunning ? 'av/stop_white' : 'maps/directions_run_white',
             size: 24
           ),
           onPressed: _isRunning ? _handleRunStopped : _handleRunStarted
         );
     }
   }
 
+  @override
   Widget build() {
     return new Scaffold(
       toolbar: buildToolBar(),
       body: buildBody(),
       snackBar: buildSnackBar(),
       floatingActionButton: buildFloatingActionButton(),
       drawer: _drawerShowing ? buildDrawer() : null
     );
   }
 }