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

sky/sdk/lib/framework/components2/input.dart

Index: sky/sdk/lib/framework/components2/input.dart
diff --git a/sky/sdk/lib/framework/components2/input.dart b/sky/sdk/lib/framework/components2/input.dart
index c8a5477fb728d2d0aa85a027cc70faae2f72de92..84415805811b4be45bbcd71ed3a527d9be7bbf44 100644
--- a/sky/sdk/lib/framework/components2/input.dart
+++ b/sky/sdk/lib/framework/components2/input.dart
@@ -20,12 +20,10 @@ class Input extends Component {
          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('''
@@ -102,4 +100,10 @@ class Input extends Component {
     );
   }
 
+  void didUnmount() {
+    if (_isAttachedToKeyboard)
+      keyboard.hide();
+    super.didUnmount();
+  }
+
 }