Fix analyzer warnings

 - Remove unused imports
 - Remove unused, broken constructor for MineDiggerApp

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

@@ -25,7 +25,6 @@ import 'package:sky/widgets/widget.dart';
 import 'fitness_types.dart';
 import 'fitness_item.dart';
 import 'measurement.dart';
-import 'meal.dart';
 
 class FitnessItemList extends Component {
   FitnessItemList({ Key key, this.items, this.onDismissed }) : super(key: key);

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

@@ -12,7 +12,6 @@ import 'package:sky/widgets/material.dart';
 import 'package:sky/widgets/navigator.dart';
 import 'package:sky/widgets/scaffold.dart';
 import 'package:sky/widgets/scrollable_viewport.dart';
-import 'package:sky/widgets/snack_bar.dart';
 import 'package:sky/widgets/theme.dart';
 import 'package:sky/widgets/tool_bar.dart';
 

sky/sdk/example/mine_digger/lib/main.dart

@@ -38,11 +38,6 @@ const List<TextStyle> textStyles = const <TextStyle>[
 enum CellState { covered, exploded, cleared, flagged, shown }
 
 class MineDiggerApp extends App {
-
-  void initState() {
-    resetGame();
-  }
-
   static const int rows = 9;
   static const int cols = 9;
   static const int totalMineCount = 11;
@@ -56,18 +51,8 @@ class MineDiggerApp extends App {
   // |uiState| keeps track of the visible player progess.
   List<List<CellState>> uiState;
 
-  Game(this.app) {
-    randomSeed = 22;
-    // Colors for each mine count:
-    // 0 - none, 1 - blue, 2-green, 3-red, 4-black, 5-dark red .. etc.
-    textStyles.add(new TextStyle(color: const Color(0xFF555555), fontWeight: bold));
-    textStyles.add(new TextStyle(color: const Color(0xFF0094FF), fontWeight: bold));
-    textStyles.add(new TextStyle(color: const Color(0xFF13A023), fontWeight: bold));
-    textStyles.add(new TextStyle(color: const Color(0xFFDA1414), fontWeight: bold));
-    textStyles.add(new TextStyle(color: const Color(0xFF1E2347), fontWeight: bold));
-    textStyles.add(new TextStyle(color: const Color(0xFF7F0037), fontWeight: bold));
-    textStyles.add(new TextStyle(color: const Color(0xFFE93BE9), fontWeight: bold));
-    initialize();
+  void initState() {
+    resetGame();
   }
 
   void resetGame() {

sky/sdk/lib/widgets/dismissable.dart

@@ -183,8 +183,10 @@ class Dismissable extends AnimatedComponent {
   }
 
   Widget build() {
-    if (_resizePerformance != null)
-      return new Container(height: _resizePerformance.variable.value);
+    if (_resizePerformance != null) {
+      AnimatedValue<double> height = _resizePerformance.variable;
+      return new Container(height: height.value);
+    }
 
     Matrix4 transform = new Matrix4.identity();
     transform.translate(_position.value.x, _position.value.y);