Fix failing test card_collection.dart.

packages/flutter/lib/widgets/dismissable.dart

@@ -175,13 +175,13 @@ class Dismissable extends StatefulComponent {
       onGestureFlingStart: _handleFlingStart,
       child: new SizeObserver(
         callback: _handleSizeChanged,
-        child: new SlideTransition(
+        child: new FadeTransition(
           performance: _fadePerformance,
-          position: new AnimatedValue<Point>(Point.origin, end: _activeCardDragEndPoint),
-          child: new FadeTransition(
+          onCompleted: _handleFadeCompleted,
+          opacity: new AnimatedValue<double>(1.0, end: 0.0),
+          child: new SlideTransition(
             performance: _fadePerformance,
-            onCompleted: _handleFadeCompleted,
-            opacity: new AnimatedValue<double>(1.0, end: 0.0),
+            position: new AnimatedValue<Point>(Point.origin, end: _activeCardDragEndPoint),
             child: child
           )
         )