Improve the RenderObject.toString() logic so that there's not blank lines everywhere and to general…

sky/sdk/lib/framework/app.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import 'dart:sky' as sky;
 import 'rendering/box.dart';
 import 'rendering/object.dart';
 import 'scheduler.dart' as scheduler;
 
 class PointerState {
@@ skipping 15 matching lines @@
     _renderView.layout(new ViewConstraints(width: sky.view.width,
                                            height: sky.view.height));
 
     scheduler.ensureVisualUpdate();
   }
 
   RenderView _renderView;
 
   Map<int, PointerState> _stateForPointer = new Map<int, PointerState>();
 
+  Function onFrame;
+
   RenderBox get root => _renderView.child;
   void set root(RenderBox value) {
     _renderView.child = value;
   }
   void _beginFrame(double timeStamp) {
+    if (onFrame != null)
+      onFrame();
     RenderObject.flushLayout();
     _renderView.paintFrame();
   }
 
   void _handleEvent(sky.Event event) {
     if (event is sky.PointerEvent) {
       _handlePointerEvent(event);
     } else if (event is sky.GestureEvent) {
       HitTestResult result = new HitTestResult();
       _renderView.hitTest(result, position: new sky.Point(event.x, event.y));
@@ skipping 34 matching lines @@
     state.lastPosition = position;
 
     dispatchEvent(event, state.result);
   }
 
   void dispatchEvent(sky.Event event, HitTestResult result) {
     assert(result != null);
     for (RenderObject node in result.path.reversed)
       node.handleEvent(event);
   }
+
+  String toString() => 'Render Tree:\n${_renderView}';
+
+  void debugDumpRenderTree() {
+    toString().split('\n').forEach(print);
+  }
+  
 }