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

sky/sdk/lib/framework/editing2/editable_text.dart

Index: sky/sdk/lib/framework/editing2/editable_text.dart
diff --git a/sky/sdk/lib/framework/editing2/editable_text.dart b/sky/sdk/lib/framework/editing2/editable_text.dart
index 711e930360c196665a5ddd2f588849160132047a..430933bf997d0d2f117bf3c76fa46ac95797911c 100644
--- a/sky/sdk/lib/framework/editing2/editable_text.dart
+++ b/sky/sdk/lib/framework/editing2/editable_text.dart
@@ -9,6 +9,9 @@ import 'editable_string.dart';
 
 class EditableText extends Component {
 
+  EditableText({Object key, this.value, this.focused})
+      : super(key: key, stateful: true);
+
   // static final Style _cursorStyle = new Style('''
   //   width: 2px;
   //   height: 1.2em;
@@ -22,17 +25,15 @@ class EditableText extends Component {
 
   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 syncFields(EditableText source) {
+    value = source.value;
+    focused = source.focused;
   }
 
+  Timer _cursorTimer;
+  bool _showCursor = false;
+
   void _cursorTick(Timer timer) {
     setState(() {
       _showCursor = !_showCursor;
@@ -45,6 +46,12 @@ class EditableText extends Component {
         new Duration(milliseconds: 500), _cursorTick);
   }
 
+  void didUnmount() {
+    if (_cursorTimer != null)
+      _stopCursorTimer();
+    super.didUnmount();
+  }
+
   void _stopCursorTimer() {
     _cursorTimer.cancel();
     _cursorTimer = null;