Revert "Speedup Observatory elements first time rendering"

runtime/observatory/lib/src/elements/helpers/rendering_scheduler.dart

Index: runtime/observatory/lib/src/elements/helpers/rendering_scheduler.dart
diff --git a/runtime/observatory/lib/src/elements/helpers/rendering_scheduler.dart b/runtime/observatory/lib/src/elements/helpers/rendering_scheduler.dart
index dd8b5c88a8870d5ad1c3e05c7d308013d83ffa49..e3e81e07c22b06d3b4f8ff2af07fc9624ffbd9fd 100644
--- a/runtime/observatory/lib/src/elements/helpers/rendering_scheduler.dart
+++ b/runtime/observatory/lib/src/elements/helpers/rendering_scheduler.dart
@@ -32,7 +32,6 @@ class RenderingScheduler<T extends Renderable> implements RenderingTask {
   bool _dirty = false;
   bool _renderingScheduled = false;
   bool _notificationScheduled = false;
-  bool _waitForBarrier = false;
 
   /// Element managed by this scheduler.
   final T element;
@@ -104,8 +103,7 @@ class RenderingScheduler<T extends Renderable> implements RenderingTask {
   void scheduleRendering() {
     if (_renderingScheduled) return;
     if (!_enabled) return;
-    queue.enqueue(this, waitForBarrier: _waitForBarrier);
-    _waitForBarrier = true;
+    queue.enqueue(this);
     _renderingScheduled = true;
   }