Revert "Build Observatory with runtime"

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

Index: runtime/observatory/lib/src/elements/library_ref.dart
diff --git a/runtime/observatory/lib/src/elements/library_ref.dart b/runtime/observatory/lib/src/elements/library_ref.dart
deleted file mode 100644
index cbe7d4b91520eec0f60b2afae03d7b5335e72ded..0000000000000000000000000000000000000000
--- a/runtime/observatory/lib/src/elements/library_ref.dart
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright (c) 2013, 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 library_ref_element;
-
-import 'package:polymer/polymer.dart';
-import 'service_ref.dart';
-
-@CustomTag('library-ref')
-class LibraryRefElement extends ServiceRefElement {
-  LibraryRefElement.created() : super.created();
-}