Improve _AnimatedEvaluation.toString

...and fix a typo in a setState assert message.

packages/flutter/lib/src/animation/tween.dart

@@ -43,7 +43,7 @@ class _AnimatedEvaluation<T> extends Animation<T> with AnimationWithParentMixin<
 
   @override
   String toString() {
-    return '$parent\u27A9$_evaluatable';
+    return '$parent\u27A9$_evaluatable\u27A9$value';
   }
 
   @override

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

@@ -384,7 +384,7 @@ abstract class State<T extends StatefulWidget> {
     assert(() {
       if (_debugLifecycleState == _StateLifecycle.defunct) {
         throw new FlutterError(
-          'setState() called after dipose(): $this\n'
+          'setState() called after dispose(): $this\n'
           'This error happens if you call setState() on State object for a widget that\n'
           'no longer appears in the widget tree (e.g., whose parent widget no longer\n'
           'includes the widget in its build). This error can occur when code calls\n'