Converted Observatory object-common element

runtime/observatory/tests/observatory_ui/mocks/objects/retaining_path.dart

+// Copyright (c) 2016, 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.
+
+part of mocks;
+
+class RetainingPathMock implements M.RetainingPath {
+  final Iterable<M.RetainingPathItem> elements;
+
+  const RetainingPathMock({this.elements: const []});
+}
+
+class RetainingPathItemMock implements M.RetainingPathItem {
+  final M.ObjectRef source;
+  final M.InstanceRef parentField;
+  final int parentListIndex;
+  final int parentWordOffset;
+
+  const RetainingPathItemMock({this.source: const InstanceRefMock(),
+                               this.parentField, this.parentListIndex,
+                               this.parentWordOffset});
+}