Fix analyzer warnings

sky/packages/sky/example/fitness/lib/feed.dart

@@ -90,7 +90,7 @@ class FeedFragment extends StatefulComponent {
   }
 
   Drawer buildDrawer() {
-    if (_drawerStatus == DrawerStatus.inactive)
+    if (_drawerStatus == AnimationStatus.dismissed)
       return null;
     return new Drawer(
       showing: _drawerShowing,
@@ -122,16 +122,16 @@ class FeedFragment extends StatefulComponent {
   }
 
   bool _drawerShowing = false;
-  DrawerStatus _drawerStatus = DrawerStatus.inactive;
+  AnimationStatus _drawerStatus = AnimationStatus.dismissed;
 
   void _handleOpenDrawer() {
     setState(() {
       _drawerShowing = true;
-      _drawerStatus = DrawerStatus.active;
+      _drawerStatus = AnimationStatus.forward;
     });
   }
 
-  void _handleDrawerStatusChange(DrawerStatus status) {
+  void _handleDrawerStatusChange(AnimationStatus status) {
     setState(() {
       _drawerStatus = status;
     });

sky/packages/sky/lib/widgets/scrollable.dart

@@ -43,7 +43,8 @@ abstract class Scrollable extends StatefulComponent {
     _toEndAnimation = new AnimatedSimulation(_tickScrollOffset);
     _toOffsetAnimation = new AnimationPerformance()
       ..addListener(() {
-        scrollTo(_toOffsetAnimation.variable.value);
+        AnimatedValue<double> offset = _toOffsetAnimation.variable;
+        scrollTo(offset.value);
       });
   }
 

sky/packages/sky/lib/widgets/snack_bar.dart

@@ -9,7 +9,6 @@ import 'package:sky/animation/animation_performance.dart';
 import 'package:sky/painting/text_style.dart';
 import 'package:sky/theme/typography.dart' as typography;
 import 'package:sky/widgets/animated_container.dart';
-import 'package:sky/widgets/animated_component.dart';
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/widgets/default_text_style.dart';
 import 'package:sky/widgets/material.dart';