[Effen] Add AnimatedComponent base class

sky/framework/editing/editable_text.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import '../fn.dart';
 import '../theme/colors.dart';
 import 'dart:async';
 import 'editable_string.dart';
 
 class EditableText extends Component {
@@ skipping 14 matching lines @@
     text-decoration: underline;'''
   );
 
   EditableString value;
   bool focused;
   Timer _cursorTimer;
   bool _showCursor = false;
 
   EditableText({Object key, this.value, this.focused})
       : super(key: key, stateful: true) {
+    onDidUnmount(() {
+      if (_cursorTimer != null)
+        _stopCursorTimer();
+    });
   }
 
   void _cursorTick(Timer timer) {
     setState(() {
       _showCursor = !_showCursor;
     });
   }
 
   void _startCursorTimer() {
     _showCursor = true;
     _cursorTimer = new Timer.periodic(
         new Duration(milliseconds: 500), _cursorTick);
   }
 
   void _stopCursorTimer() {
     _cursorTimer.cancel();
     _cursorTimer = null;
     _showCursor = false;
   }
 
-  void didUnmount() {
-    if (_cursorTimer != null)
-      _stopCursorTimer();
-  }
-
   Node build() {
     if (focused && _cursorTimer == null)
       _startCursorTimer();
     else if (!focused && _cursorTimer != null)
       _stopCursorTimer();
 
     List<Node> children = new List<Node>();
 
     if (!value.composing.isValid) {
       children.add(new Text(value.text));
@@ skipping 18 matching lines @@
 
     if (_showCursor)
       children.add(new Container(key: 'cursor', style: _cusorStyle));
 
     return new Container(
       style: _style,
       children: children
     );
   }
 }