Rework error handling in the service protocol and in Observatory.

runtime/observatory/lib/src/elements/object_view.dart

Index: runtime/observatory/lib/src/elements/object_view.dart
diff --git a/runtime/observatory/lib/src/elements/object_view.dart b/runtime/observatory/lib/src/elements/object_view.dart
index c4a2696aee08a1be402ed6dd076d9333e2e6ea07..863a2d44cb4e0440ecdc6847f794cc5450cbf4ea 100644
--- a/runtime/observatory/lib/src/elements/object_view.dart
+++ b/runtime/observatory/lib/src/elements/object_view.dart
@@ -4,6 +4,7 @@
 
 library object_view;
 
+import 'dart:async';
 import 'observatory_element.dart';
 import 'package:observatory/service.dart';
 import 'package:polymer/polymer.dart';
@@ -14,7 +15,7 @@ class ObjectViewElement extends ObservatoryElement {
 
   ObjectViewElement.created() : super.created();
 
-  void refresh(Function onDone) {
-    object.reload().whenComplete(onDone);
+  Future refresh() {
+    return object.reload();
   }
 }