Restore "Speedup Observatory elements first time rendering"

runtime/observatory/lib/src/elements/curly_block.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 curly_block_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'package:observatory/src/elements/helpers/tag.dart';
 import 'package:observatory/src/elements/helpers/rendering_scheduler.dart';
@@ skipping 34 matching lines @@
   }
 
   factory CurlyBlockElement(
       {bool expanded: false, bool disabled: false, RenderingQueue queue}) {
     assert(expanded != null);
     assert(disabled != null);
     CurlyBlockElement e = document.createElement(tag.name);
     e._r = new RenderingScheduler(e, queue: queue);
     e._expanded = expanded;
     e._disabled = disabled;
-    e._r.enable();
     return e;
   }
 
   CurlyBlockElement.created() : super.created();
 
   @override
   void attached() {
     super.attached();
     _r.enable();
   }
@@ skipping 30 matching lines @@
         ..children = [label]);
     }
     if (expanded) {
       content.add(new BRElement());
       content.addAll(_content);
     }
     content.add(new SpanElement()..text = '}');
     children = content;
   }
 }