update elements and fix some bugs

test/iron_list_dynamic_item_size_test.dart

+// Copyright (c) 2015, 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.
+@TestOn('browser')
+library polymer_elements.test.iron_list_dynamic_item_size_test;
+
+import 'dart:async';
+import 'dart:js';
+import 'package:polymer_elements/iron_list.dart';
+import 'package:polymer/polymer.dart';
+import 'package:test/test.dart';
+import 'package:web_components/web_components.dart';
+import 'common.dart';
+import 'iron_list_test_helpers.dart';
+import 'fixtures/x_list.dart';
+
+/// Uses [XList].
+main() async {
+  await initPolymer();
+
+  group('Dynamic item size', () {
+    IronList list;
+    XList container;
+
+    setUp(() {
+      container = fixture('trivialList');
+      list = container.list;
+    });
+
+    test('update size using item index', () async {
+      list.items = buildDataSet(100);
+
+      await wait(1);
+
+      var firstItem = getFirstItemFromList(list);
+      var initHeight = firstItem.offsetHeight;
+
+      list.set('items.0.index', '1\n2\n3\n4');
+      list.updateSizeForItem(0);
+      expect(firstItem.offsetHeight, greaterThan(initHeight * 3));
+
+      list.set('items.0.index', '1');
+      list.updateSizeForItem(0);
+      expect(firstItem.offsetHeight, initHeight);
+    });
+
+    test('update size using item object', () async {
+      list.items = buildDataSet(100);
+
+      await wait(1);
+
+      var firstItem = getFirstItemFromList(list);
+      var initHeight = firstItem.offsetHeight;
+
+      list.set('items.0.index', '1\n2\n3\n4');
+      list.updateSizeForItem(list.items[0]);
+      expect(firstItem.offsetHeight, greaterThan(initHeight * 3));
+
+      list.set('items.0.index', '1');
+      list.updateSizeForItem(list.items[0]);
+      expect(firstItem.offsetHeight, initHeight);
+    });
+
+    test('ignore items that are not rendered', () async {
+      list.items = buildDataSet(100);
+
+      await wait(1);
+      list.updateSizeForItem(list.items[list.jsElement['_physicalCount'] + 1]);
+    });
+
+    test('throw if the item is invalid', () async {
+      list.items = buildDataSet(100);
+
+      await wait(1);
+      var firstItem = getFirstItemFromList(list);
+      var initHeight = firstItem.offsetHeight;
+      var throws = 0;
+
+      try {
+        list.updateSizeForItem(100);
+      } catch (error) {
+        throws++;
+      }
+
+      try {
+        list.updateSizeForItem({});
+      } catch (error) {
+        throws++;
+      }
+
+      expect(throws, 2);
+    });
+  });
+}