Kill onDidMount()/onDidUnmount() in favour of just overriding the relevant methods.

sky/sdk/lib/framework/components2/input.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 '../editing2/editable_string.dart';
 import '../editing2/editable_text.dart';
 import '../editing2/keyboard.dart';
 import '../fn2.dart';
 import '../theme2/colors.dart';
 import '../theme2/typography.dart' as typography;
 import '../rendering/flex.dart';
 import 'dart:sky' as sky;
 
 typedef void ValueChanged(value);
 
 class Input extends Component {
 
   Input({Object key,
          this.placeholder,
          this.onChanged,
          this.focused})
       : super(key: key, stateful: true) {
-    _editableValue = new EditableString(text: _value,
-                                        onUpdated: _handleTextUpdated);
-    onDidUnmount(() {
-      if (_isAttachedToKeyboard)
-        keyboard.hide();
-    });
+    _editableValue = new EditableString(
+      text: _value,
+      onUpdated: _handleTextUpdated
+    );
   }
 
   // static final Style _style = new Style('''
   //   transform: translateX(0);
   //   margin: 8px;
   //   padding: 8px;
   //   border-bottom: 1px solid ${Grey[200]};
   //   align-self: center;
   //   height: 1.2em;
   //   white-space: pre;
@@ skipping 56 matching lines @@
       new FlexContainer(
         direction: FlexDirection.vertical,
         // style: _style,
         // inlineStyle: focused ? _focusedInlineStyle : null,
         children: children
       ),
       onPointerDown: (sky.Event e) => keyboard.showByRequest()
     );
   }
 
+  void didUnmount() {
+    if (_isAttachedToKeyboard)
+      keyboard.hide();
+    super.didUnmount();
+  }
+
 }