[mdv] Implement two-way binding to HTMLTextArea.value

pkg/mdv/lib/src/select_element.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of mdv;
 
 /** Extensions to the [SelectElement] API. */
 class _SelectElementExtension extends _ElementExtension {
+  _SelectedIndexBinding _valueBinding;
+
   _SelectElementExtension(SelectElement node) : super(node);
 
   SelectElement get node => super.node;
 
-  _SelectedIndexBinding _valueBinding;
-
   void bind(String name, model, String path) {
     if (name.toLowerCase() == 'selectedindex') {
       unbind('selectedindex');
       node.attributes.remove('selectedindex');
       _valueBinding = new _SelectedIndexBinding(node, model, path);
       return;
     }
     super.bind(name, model, path);
   }
 
   void unbind(String name) {
     if (name.toLowerCase() == 'selectedindex' && _valueBinding != null) {
       _valueBinding.unbind();
       _valueBinding = null;
       return;
     }
     super.unbind(name);
   }
 
   void unbindAll() {
     unbind('selectedindex');
     super.unbindAll();
   }
 }
-
-
-class _SelectedIndexBinding extends _InputBinding {
-  _SelectedIndexBinding(element, model, path) : super(element, model, path);
-
-  SelectElement get element => super.element;
-
-  void valueChanged(value) {
-    var newValue = _toInt(value);
-    if (newValue <= element.length) {
-      element.selectedIndex = newValue;
-      return;
-    }
-
-    // The binding may wish to bind to an <option> which has not yet been
-    // produced by a child <template>. Furthermore, we may need to wait for
-    // <optgroup> iterating and then for <option>.
-    //
-    // Unlike the JavaScript MDV, we don't have a special "Object.observe" event
-    // loop to schedule on. (See the the "ensureScheduled" function:
-    // https://github.com/Polymer/mdv/commit/9a51ad7ed74a292bf71662cea28acbd151ff65c8)
-    //
-    // Instead we use runAsync. Each <template repeat> needs a delay of 3:
-    //   * once to happen after the child _TemplateIterator is created
-    //   * once to be after _TemplateIterator.inputs CompoundBinding resolve
-    //   * once to be after _TemplateIterator._valueBinding PathObserver fires
-    // And then we need to do this delay sequence twice:
-    //   * once for OPTGROUP
-    //   * once for OPTION.
-    // The resulting 2 * 3 is our maxRetries.
-    var maxRetries = 6;
-    delaySetSelectedIndex() {
-      if (newValue > element.length && --maxRetries >= 0) {
-        runAsync(delaySetSelectedIndex);
-      } else {
-        element.selectedIndex = newValue;
-      }
-    }
-
-    runAsync(delaySetSelectedIndex);
-  }
-
-  void updateBinding(e) {
-    binding.value = element.selectedIndex;
-  }
-
-  // TODO(jmesserly,sigmund): I wonder how many bindings typically convert from
-  // one type to another (e.g. value-as-number) and whether it is useful to
-  // have something like a int/num binding converter (either as a base class or
-  // a wrapper).
-  static int _toInt(value) {
-    if (value is String) return int.parse(value, onError: (_) => null);
-    return value is int ? value : null;
-  }
-}