Add @override annotation to known overriden methods

sky/sdk/example/game/lib/action.dart

 part of sprites;
 
 typedef void ActionCallback();
 
 abstract class Action {
   Object _tag;
   bool _finished = false;
 
   void step(double dt);
   void update(double t) {
   }
 
   double get duration => 0.0;
 }
 
 abstract class ActionInterval extends Action {
   double _duration;
 
   bool _firstTick = true;
   double _elapsed = 0.0;
 
+  @override
   double get duration => _duration;
 
   ActionInterval([this._duration = 0.0]);
 
+  @override
   void step(double dt) {
     if (_firstTick) {
       _firstTick = false;
     } else {
       _elapsed += dt;
     }
 
     double t;
     if (this._duration == 0.0) {
       t = 1.0;
     } else {
       t = (_elapsed / _duration).clamp(0.0, 1.0);
     }
 
     update(t);
 
     if (t >= 1.0) _finished = true;
   }
 }
 
 class ActionRepeat extends ActionInterval {
   final int numRepeats;
   final ActionInterval action;
 
   ActionRepeat(this.action, this.numRepeats) {
     _duration = action.duration * numRepeats;
   }
 
+  @override
   void update(double t) {
     action.update((t * numRepeats.toDouble()) % numRepeats.toDouble());
   }
 }
 
 class ActionSequence extends ActionInterval {
   Action _a;
   Action _b;
   double _split;
 
@@ skipping 11 matching lines @@
 
     // Calculate split and duration
     _duration = _a.duration + _b.duration;
     if (_duration > 0) {
       _split = _a.duration / _duration;
     } else {
       _split = 1.0;
     }
   }
 
+  @override
   void update(double t) {
     if (t < _split) {
       // Play first action
       double ta;
       if (_split > 0.0) {
         ta = (t / _split).clamp(0.0, 1.0);
       } else {
         ta = 1.0;
       }
       _a.update(ta);
@@ skipping 10 matching lines @@
       } else {
         tb = 1.0;
       }
       _b.update(tb);
     }
   }
 }
 
 abstract class ActionInstant extends Action {
 
+  @override
   void step(double dt) {
   }
 
+  @override
   void update(double t) {
     fire();
     _finished = true;
   }
 
   void fire();
 }
 
 class ActionCallFunction extends ActionInstant {
   ActionCallback _function;
 
   ActionCallFunction(this._function);
 
+  @override
   void fire() {
     _function();
   }
 }
 
 class ActionRemoveNode extends ActionInstant {
   Node _node;
 
   ActionRemoveNode(this._node);
 
+  @override
   void fire() {
     _node.removeFromParent();
   }
 }
 
 class ActionRepeatForever extends Action {
   final ActionInterval action;
   double _elapsedInAction = 0.0;
 
   ActionRepeatForever(this.action);
 
+  @override
   step(double dt) {
     _elapsedInAction += dt;
     while (_elapsedInAction > action.duration) {
       _elapsedInAction -= action.duration;
     }
     _elapsedInAction = Math.max(_elapsedInAction, 0.0);
 
     double t;
     if (action._duration == 0.0) {
       t = 1.0;
@@ skipping 29 matching lines @@
       int aDelta = endVal.alpha - startVal.alpha;
       int rDelta = endVal.red - startVal.red;
       int gDelta = endVal.green - startVal.green;
       int bDelta = endVal.blue - startVal.blue;
       _delta = new _ColorDiff(aDelta, rDelta, gDelta, bDelta);
     } else {
       assert(false);
     }
   }
 
+  @override
   void update(double t) {
     var newVal;
 
     if (startVal is Point) {
       // Point
       double xStart = startVal.x;
       double yStart = startVal.y;
       double xDelta = _delta.x;
       double yDelta = _delta.y;
       newVal = new Point(xStart + xDelta * t, yStart + yDelta * t);
@@ skipping 59 matching lines @@
 }
 
 class _ColorDiff {
   final int alpha;
   final int red;
   final int green;
   final int blue;
 
   _ColorDiff(this.alpha, this.red, this.green, this.blue);
 }