feat(change_detection): added support for ObservableList from package:observe

modules/angular2/src/directives/observable_list_diff.dart

@@ -0,0 +1,66 @@
+library angular2.directives.observable_list_iterable_diff;
+
+import 'package:observe/observe.dart' show ObservableList;
+import 'package:angular2/change_detection.dart';
+import 'package:angular2/src/change_detection/pipes/iterable_changes.dart';
+import 'dart:async';
+
+class ObservableListDiff extends IterableChanges {
+  ChangeDetectorRef _ref;
+  ObservableListDiff(this._ref);
+
+  bool _updated = true;
+  ObservableList _collection;
+  StreamSubscription _subscription;
+
+  bool supports(obj) {
+    if (obj is ObservableList) return true;
+    throw "Cannot change the type of a collection";
+  }
+
+  onDestroy() {
+    if (this._subscription != null) {
+      this._subscription.cancel();
+      this._subscription = null;
+      this._collection = null;
+    }
+  }
+
+  dynamic transform(ObservableList collection, [List args]) {
+    // A new collection instance is passed in.
+    // - We need to set up a listener.
+    // - We need to transform collection.
+    if (!identical(_collection, collection)) {
+      _collection = collection;
+
+      if (_subscription != null) _subscription.cancel();
+      _subscription = collection.changes.listen((_) {
+        _updated = true;
+        _ref.requestCheck();
+      });
+      _updated = false;
+      return super.transform(collection, args);
+
+    // An update has been registered since the last change detection check.
+    // - We reset the flag.
+    // - We diff the collection.
+    } else if (_updated){
+      _updated = false;
+      return  super.transform(collection, args);
+
+    // No updates has been registered.
+    // Returning this tells change detection that object has not change,
+    // so it should NOT update the binding.
+    } else {
+      return this;
+    }
+  }
+}
+
+class ObservableListDiffFactory implements PipeFactory {
+  const ObservableListDiffFactory();
+  bool supports(obj) => obj is ObservableList;
+  Pipe create(ChangeDetectorRef cdRef) {
+    return new ObservableListDiff(cdRef);
+  }
+}