move polymer.dart into dart svn

samples/third_party/todomvc/web/editable_label.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.
+
+library editable_label;
+
+import 'dart:html';
+import 'package:polymer/polymer.dart';
+
+/**
+ * Label whose [value] can be edited by double clicking. When editing, it
+ * displays a form and input element, otherwise it displays the label.
+ */
+class EditableLabel extends PolymerElement with ObservableMixin {
+  @observable bool editing = false;
+  @observable String value = '';
+  bool get applyAuthorStyles => true;
+
+  InputElement get _editBox => getShadowRoot("editable-label").query('#edit');
+
+  void edit() {
+    editing = true;
+
+    // This causes _editBox to be inserted.
+    performMicrotaskCheckpoint();
+
+    // For IE and Firefox: use .focus(), then reset the value to move the
+    // cursor to the end.
+    _editBox.focus();
+    _editBox.value = '';
+    _editBox.value = value;
+  }
+
+  void update(Event e) {
+    e.preventDefault(); // don't submit the form
+    if (!editing) return; // bail if user canceled
+    value = _editBox.value;
+    editing = false;
+  }
+
+  void maybeCancel(KeyboardEvent e) {
+    if (e.keyCode == KeyCode.ESC) {
+      editing = false;
+    }
+  }
+}
+
+@polymerInitMethod
+void _init() {
+  registerPolymerElement('editable-label', () => new EditableLabel());
+}