Fixed defaultMix initialization.

spine-as3/spine-as3/src/spine/AnimationStateData.as

@@ -4,7 +4,7 @@ import spine.animation.Animation;
 public class AnimationStateData {
 	private var _skeletonData:SkeletonData;
 	private var animationToMixTime:Object = new Object();
-	public var defaultMix:Number;
+	public var defaultMix:Number = 0;
 
 	public function AnimationStateData (skeletonData:SkeletonData) {
 		_skeletonData = skeletonData;