Omnibus Observatory UI fixes:

runtime/observatory/tests/observatory_ui/persistent_handles_page/element_test.dart

Index: runtime/observatory/tests/observatory_ui/persistent_handles_page/element_test.dart
diff --git a/runtime/observatory/tests/observatory_ui/persistent_handles_page/element_test.dart b/runtime/observatory/tests/observatory_ui/persistent_handles_page/element_test.dart
index ff3f97ca0115e76054beb30f437eaa9b4b0ec4dc..43d8c76ea0fd7f1c0f14de65f9e019e8bb54f6a6 100644
--- a/runtime/observatory/tests/observatory_ui/persistent_handles_page/element_test.dart
+++ b/runtime/observatory/tests/observatory_ui/persistent_handles_page/element_test.dart
@@ -15,10 +15,10 @@ main() {
   final events = new EventRepositoryMock();
   final notifs = new NotificationRepositoryMock();
   final repository = new PersistentHandlesRepositoryMock();
-  final instances = new InstanceRepositoryMock();
+  final objects = new ObjectRepositoryMock();
   test('instantiation', () {
     final e = new PersistentHandlesPageElement(
-        vm, isolate, events, notifs, repository, instances);
+        vm, isolate, events, notifs, repository, objects);
     expect(e, isNotNull, reason: 'element correctly created');
     expect(e.isolate, equals(isolate));
   });
@@ -28,9 +28,9 @@ main() {
       expect(i, equals(isolate));
       return const PersistentHandlesMock();
     }, count: 1));
-    final instances = new InstanceRepositoryMock();
+    final objects = new ObjectRepositoryMock();
     final e = new PersistentHandlesPageElement(
-        vm, isolate, events, notifs, repository, instances);
+        vm, isolate, events, notifs, repository, objects);
     document.body.append(e);
     await e.onRendered.first;
     expect(e.children.length, isNonZero, reason: 'has elements');