Revert "Build Observatory with runtime"

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

-// 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 context_ref_element;
-
-import 'package:polymer/polymer.dart';
-import 'package:observatory/service.dart';
-import 'service_ref.dart';
-
-@CustomTag('context-ref')
-class ContextRefElement extends ServiceRefElement {
-  ContextRefElement.created() : super.created();
-
-  // TODO(turnidge): This is here to workaround vm/dart2js differences.
-  dynamic expander() {
-    return expandEvent;
-  }
-
-  void expandEvent(bool expand, Function onDone) {
-    assert(ref is Context);
-    if (expand) {
-      ref.reload().then((result) {
-        ref = result;
-        notifyPropertyChange(#ref, 0, 1);
-      }).whenComplete(onDone);
-    } else {
-      Context refMap = ref;
-      refMap.variables = null;
-      onDone();
-    }
-  }
-}