update elements and fix some bugs

test/iron_list_different_heights_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_different_heights_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('Different heights', () {
+    IronList list;
+    XList container;
+
+    setUp(() {
+      container = fixture('trivialList');
+      list = container.list;
+    });
+
+    test('render without gaps 1', () async {
+      list.items = [
+        {'index': 0, 'height': 791},
+        {'index': 1, 'height': 671}
+      ];
+
+      await wait(1);
+      list.addAll('items', [
+        {'index': 2, 'height': 251},
+        {'index': 3, 'height': 191},
+        {'index': 4, 'height': 151},
+        {'index': 5, 'height': 191},
+        {'index': 6, 'height': 51},
+        {'index': 7, 'height': 51},
+        {'index': 8, 'height': 51},
+      ]);
+
+      list.on['scroll'].first.then((_) {
+        expect(isFullOfItems(list), isTrue);
+      });
+
+      var done = new Completer();
+      simulateScroll({'list': list, 'contribution': 15, 'target': 100000}, (_) {
+        done.complete();
+      });
+
+      return done.future;
+    });
+
+    test('render without gaps 2', () async {
+      var height = 2, items = [];
+
+      while (items.length < 15) {
+        items.add({'height': height});
+        height *= 1.5;
+      }
+      list.items = items;
+
+      await wait(1);
+      list.on['scroll'].first.then((_) {
+        expect(isFullOfItems(list), isTrue);
+      });
+
+      var done = new Completer();
+      simulateScroll({'list': list, 'contribution': 20, 'target': 100000}, (_) {
+        done.complete();
+      });
+
+      return done.future;
+    });
+
+    test('render without gaps 3', () async {
+      var heights = [
+        20,
+        100,
+        140,
+        117,
+        800,
+        50,
+        15,
+        80,
+        90,
+        255,
+        20,
+        15,
+        19,
+        250,
+        314
+      ];
+
+      list.items = heights.map((height) {
+        return {'height': height};
+      }).toList();
+
+      await wait(1);
+      list.on['scroll'].first.then((_) {
+        expect(isFullOfItems(list), isTrue);
+      });
+
+      var done = new Completer();
+      simulateScroll({'list': list, 'contribution': 20, 'target': 100000}, (_) {
+        done.complete();
+      });
+
+      return done.future;
+    });
+  });
+}