Include opacity in FadeTransition logging (#15073)

packages/flutter/lib/src/widgets/animated_cross_fade.dart

@@ -247,13 +247,13 @@ class _AnimatedCrossFadeState extends State<AnimatedCrossFade> with TickerProvid
   Animation<double> _initAnimation(Curve curve, bool inverted) {
     Animation<double> animation = new CurvedAnimation(
       parent: _controller,
-      curve: curve
+      curve: curve,
     );
 
     if (inverted) {
       animation = new Tween<double>(
-          begin: 1.0,
-          end: 0.0
+        begin: 1.0,
+        end: 0.0,
       ).animate(animation);
     }
 

packages/flutter/lib/src/widgets/transitions.dart

@@ -332,6 +332,12 @@ class FadeTransition extends SingleChildRenderObjectWidget {
     renderObject
       ..opacity = opacity;
   }
+
+  @override
+  void debugFillProperties(DiagnosticPropertiesBuilder description) {
+    super.debugFillProperties(description);
+    description.add(new DiagnosticsProperty<Animation<double>>('opacity', opacity));
+  }
 }
 
 /// An interpolation between two relative rects.