Add @override annotation to known overriden methods

sky/sdk/lib/widgets/tabs.dart

Index: sky/sdk/lib/widgets/tabs.dart
diff --git a/sky/sdk/lib/widgets/tabs.dart b/sky/sdk/lib/widgets/tabs.dart
index 5812413fef1f657f97334027da45122fa42ce2e7..0ee96e93571ffadb05c3efd2c9331c6d4db1afe1 100644
--- a/sky/sdk/lib/widgets/tabs.dart
+++ b/sky/sdk/lib/widgets/tabs.dart
@@ -88,11 +88,13 @@ class RenderTabBar extends RenderBox with
     }
   }
 
+  @override
   void setupParentData(RenderBox child) {
     if (child.parentData is! TabBarParentData)
       child.parentData = new TabBarParentData();
   }
 
+  @override
   double getMinIntrinsicWidth(BoxConstraints constraints) {
     BoxConstraints widthConstraints =
         new BoxConstraints(maxWidth: constraints.maxWidth, maxHeight: constraints.maxHeight);
@@ -108,6 +110,7 @@ class RenderTabBar extends RenderBox with
     return constraints.constrainWidth(width);
   }
 
+  @override
   double getMaxIntrinsicWidth(BoxConstraints constraints) {
     BoxConstraints widthConstraints =
         new BoxConstraints(maxWidth: constraints.maxWidth, maxHeight: constraints.maxHeight);
@@ -129,8 +132,10 @@ class RenderTabBar extends RenderBox with
 
   double _getIntrinsicHeight(BoxConstraints constraints) => constraints.constrainHeight(_tabBarHeight);
 
+  @override
   double getMinIntrinsicHeight(BoxConstraints constraints) => _getIntrinsicHeight(constraints);
 
+  @override
   double getMaxIntrinsicHeight(BoxConstraints constraints) => _getIntrinsicHeight(constraints);
 
   void layoutFixedWidthTabs() {
@@ -191,6 +196,7 @@ class RenderTabBar extends RenderBox with
     }
   }
 
+  @override
   void performLayout() {
     assert(constraints is BoxConstraints);
 
@@ -209,6 +215,7 @@ class RenderTabBar extends RenderBox with
       reportLayoutChangedIfNeeded();
   }
 
+  @override
   void hitTestChildren(HitTestResult result, { Point position }) {
     defaultHitTestChildren(result, position: position);
   }
@@ -226,9 +233,10 @@ class RenderTabBar extends RenderBox with
     canvas.drawRect(rect, new Paint()..color = indicatorColor);
   }
 
+  @override
   void paint(PaintingCanvas canvas, Offset offset) {
     if (backgroundColor != null) {
-      double width = layoutWidths != null 
+      double width = layoutWidths != null
         ? layoutWidths.reduce((sum, width) => sum + width)
         : size.width;
       Rect rect = offset & new Size(width, size.height);
@@ -256,19 +264,23 @@ class TabBarWrapper extends MultiChildRenderObjectWrapper {
     this.textAndIcons,
     this.scrollable: false,
     this.onLayoutChanged,
-    String key 
+    String key
   }) : super(key: key, children: children);
 
   final int selectedIndex;
   final Color backgroundColor;
   final Color indicatorColor;
-  final bool textAndIcons; 
+  final bool textAndIcons;
   final bool scrollable;
   final LayoutChanged onLayoutChanged;
 
+  @override
   RenderTabBar get root => super.root;
+
+  @override
   RenderTabBar createNode() => new RenderTabBar(onLayoutChanged);
 
+  @override
   void syncRenderObject(Widget old) {
     super.syncRenderObject(old);
     root.selectedIndex = selectedIndex;
@@ -310,6 +322,7 @@ class Tab extends Component {
     return new Icon(type: label.icon, size: _kTabIconSize);
   }
 
+  @override
   Widget build() {
     Widget labelContents;
     if (label.icon == null) {
@@ -324,7 +337,7 @@ class Tab extends Component {
             margin: const EdgeDims.only(bottom: 10.0)
           ),
           _buildLabelText()
-        ], 
+        ],
         justifyContent: FlexJustifyContent.center,
         alignItems: FlexAlignItems.center,
         direction: FlexDirection.vertical
@@ -332,7 +345,7 @@ class Tab extends Component {
     }
 
     Widget highlightedLabel = new Opacity(
-      child: labelContents, 
+      child: labelContents,
       opacity: selected ? 1.0 : 0.7
     );
 
@@ -351,6 +364,7 @@ class TabBarScrollBehavior extends ScrollBehavior {
 
   double maxScrollOffset;
 
+  @override
   Simulation release(Particle particle) {
     if (particle.velocity == 0.0 || particle.position < 0.0 || particle.position >= maxScrollOffset)
       return null;
@@ -362,6 +376,7 @@ class TabBarScrollBehavior extends ScrollBehavior {
     return new Simulation(system, terminationCondition: () => particle.position == 0.0);
   }
 
+  @override
   double applyCurve(double scrollOffset, double scrollDelta) {
     return (scrollOffset + scrollDelta).clamp(0.0, maxScrollOffset);
   }
@@ -381,6 +396,7 @@ class TabBar extends Scrollable {
   SelectedIndexChanged onChanged;
   bool scrollable;
 
+  @override
   void syncFields(TabBar source) {
     super.syncFields(source);
     labels = source.labels;
@@ -391,7 +407,10 @@ class TabBar extends Scrollable {
       scrollTo(0.0);
   }
 
+  @override
   ScrollBehavior createScrollBehavior() => new TabBarScrollBehavior();
+
+  @override
   TabBarScrollBehavior get scrollBehavior => super.scrollBehavior;
 
   void _handleTap(int tabIndex) {
@@ -423,6 +442,7 @@ class TabBar extends Scrollable {
     });
   }
 
+  @override
   Widget buildContent() {
     assert(labels != null && labels.isNotEmpty);
     List<Widget> tabs = <Widget>[];
@@ -441,7 +461,7 @@ class TabBar extends Scrollable {
     }
 
     TabBarWrapper tabBarWrapper = new TabBarWrapper(
-      children: tabs, 
+      children: tabs,
       selectedIndex: selectedIndex,
       backgroundColor: backgroundColor,
       indicatorColor: indicatorColor,
@@ -489,6 +509,7 @@ class TabNavigator extends Component {
       onChanged(tabIndex);
   }
 
+  @override
   Widget build() {
     assert(views != null && views.isNotEmpty);
     assert(selectedIndex >= 0 && selectedIndex < views.length);