[Effen] Add AnimatedComponent base class

sky/framework/components/input.dart

Index: sky/framework/components/input.dart
diff --git a/sky/framework/components/input.dart b/sky/framework/components/input.dart
index e284f34180e2cbe62d3df6e9326c7aa8bb636d19..b07e404b886a571892a9d119797171cecb1e4353 100644
--- a/sky/framework/components/input.dart
+++ b/sky/framework/components/input.dart
@@ -49,6 +49,10 @@ class Input extends Component {
       : super(key: key, stateful: true) {
     _editableValue = new EditableString(text: _value,
                                         onUpdated: _handleTextUpdated);
+    onDidUnmount(() {
+      if (_isAttachedToKeyboard)
+        keyboard.hide();
+    });
   }
 
   void _handleTextUpdated() {
@@ -60,11 +64,6 @@ class Input extends Component {
     }
   }
 
-  void didUnmount() {
-    if (_isAttachedToKeyboard)
-      keyboard.hide();
-  }
-
   Node build() {
     if (focused && !_isAttachedToKeyboard) {
       keyboard.show(_editableValue.stub);