[mdv] implement full DOM stability

pkg/mdv/test/template_element_test.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 template_element_test;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html';
 import 'dart:math' as math;
@@ skipping 55 matching lines @@
   recursivelySetTemplateModel(element, model) {
     for (var node in element.queryAll('*')) {
       if (node.isTemplate) node.model = model;
     }
   }
 
   dispatchEvent(type, target) {
     target.dispatchEvent(new Event(type, cancelable: false));
   }
 
+  var expando = new Expando('test');
+  void addExpandos(node) {
+    while (node != null) {
+      expando[node] = node.text;
+      node = node.nextNode;
+    }
+  }
+
+  void checkExpandos(node) {
+    expect(node, isNotNull);
+    while (node != null) {
+      expect(expando[node], node.text);
+      node = node.nextNode;
+    }
+  }
+
   test('Template', () {
     var div = createTestHtml('<template bind={{}}>text</template>');
     recursivelySetTemplateModel(div, null);
     deliverChangeRecords();
     expect(div.nodes.length, 2);
     expect(div.nodes.last.text, 'text');
   });
 
   test('Template bind, no parent', () {
     var div = createTestHtml('<template bind>text</template>');
@@ skipping 174 matching lines @@
 
     model.addAll(toSymbols([3, 4]));
     deliverChanges(model);
     expect(div.nodes.length, 4);
 
     model.removeRange(1, 2);
     deliverChanges(model);
     expect(div.nodes.length, 3);
   });
 
+  test('Repeat - Reuse Instances', () {
+    var div = createTestHtml('<template repeat>{{ val }}</template>');
+
+    var model = toSymbols([
+      {'val': 10},
+      {'val': 5},
+      {'val': 2},
+      {'val': 8},
+      {'val': 1}
+    ]);
+    recursivelySetTemplateModel(div, model);
+
+    deliverChanges(model);
+    expect(div.nodes.length, 6);
+    var template = div.firstChild;
+
+    addExpandos(template.nextNode);
+    checkExpandos(template.nextNode);
+
+    final VAL = const Symbol('val');
+    model.sort((a, b) => a[VAL] - b[VAL]);
+    deliverChanges(model);
+    checkExpandos(template.nextNode);
+
+    model = toObservable(model.reversed);
+    recursivelySetTemplateModel(div, model);
+    deliverChanges(model);
+    checkExpandos(template.nextNode);
+
+    for (var item in model) {
+      item[VAL] += 1;
+    }
+
+    deliverChanges(model);
+    expect(div.nodes[1].text, "11");
+    expect(div.nodes[2].text, "9");
+    expect(div.nodes[3].text, "6");
+    expect(div.nodes[4].text, "3");
+    expect(div.nodes[5].text, "2");
+  });
+
+  test('Bind - Reuse Instance', () {
+    var div = createTestHtml(
+        '<template bind="{{ foo }}">{{ bar }}</template>');
+
+    var model = toObservable({ 'foo': { 'bar': 5 }});
+    recursivelySetTemplateModel(div, model);
+
+    deliverChanges(model);
+    expect(div.nodes.length, 2);
+    var template = div.firstChild;
+
+    addExpandos(template.nextNode);
+    checkExpandos(template.nextNode);
+
+    model = toObservable({'foo': model['foo']});
+    recursivelySetTemplateModel(div, model);
+    deliverChanges(model);
+    checkExpandos(template.nextNode);
+  });
+
   test('Repeat-Empty', () {
     var div = createTestHtml(
         '<template repeat>text</template>');
 
     var model = toSymbols([0, 1, 2]);
     recursivelySetTemplateModel(div, model);
 
     deliverChanges(model);
     expect(div.nodes.length, 4);
 
@@ skipping 1283 matching lines @@
       result[k] = _deepToSymbol(v);
     });
     return result;
   }
   if (value is Iterable) {
     return value.map(_deepToSymbol).toList();
   }
   return value;
 }