Restore "Speedup Observatory elements first time rendering"

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

Index: runtime/observatory/lib/src/elements/curly_block.dart
diff --git a/runtime/observatory/lib/src/elements/curly_block.dart b/runtime/observatory/lib/src/elements/curly_block.dart
index b320a9a04e418a427ee2558f764e162d7ffe758e..12ef047040533d76be272b3dc17f8d6a67ba22bf 100644
--- a/runtime/observatory/lib/src/elements/curly_block.dart
+++ b/runtime/observatory/lib/src/elements/curly_block.dart
@@ -52,7 +52,6 @@ class CurlyBlockElement extends HtmlElement implements Renderable {
     e._r = new RenderingScheduler(e, queue: queue);
     e._expanded = expanded;
     e._disabled = disabled;
-    e._r.enable();
     return e;
   }