Revert "Build Observatory with runtime"

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

Index: runtime/observatory/lib/src/elements/error_ref.dart
diff --git a/runtime/observatory/lib/src/elements/error_ref.dart b/runtime/observatory/lib/src/elements/error_ref.dart
deleted file mode 100644
index 14d364e37b196cfc87fd325af3d86c22d5eba2c2..0000000000000000000000000000000000000000
--- a/runtime/observatory/lib/src/elements/error_ref.dart
+++ /dev/null
@@ -1,14 +0,0 @@
-// Copyright (c) 2014, 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 error_ref_element;
-
-import 'package:polymer/polymer.dart';
-import 'package:observatory/service.dart';
-import 'service_ref.dart';
-
-@CustomTag('error-ref')
-class ErrorRefElement extends ServiceRefElement {
-  ErrorRefElement.created() : super.created();
-}