Remove bogus assert in layout()

sky/sdk/lib/framework/layout2.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 'node.dart';
 import 'dart:sky' as sky;
 
 // ABSTRACT LAYOUT
 
 class ParentData {
@@ skipping 107 matching lines @@
   }
   void _doLayout() {
     try {
       assert(_relayoutSubtreeRoot == this);
       performLayout();
     } catch (e, stack) {
       print('Exception raised during layout of ${this}: ${e}');
       print(stack);
       return;
     }
-    assert(!_needsLayout); // check that the relayout() method marked us "not dirty"
+    _needsLayout = false;
   }
   void layout(dynamic constraints, { bool parentUsesSize: false }) {
     RenderNode relayoutSubtreeRoot;
     if (!parentUsesSize || sizedByParent || parent is! RenderNode)
       relayoutSubtreeRoot = this;
     else
       relayoutSubtreeRoot = parent._relayoutSubtreeRoot;
     if (!needsLayout && constraints == _constraints && relayoutSubtreeRoot == _relayoutSubtreeRoot)
       return;
     _constraints = constraints;
@@ skipping 806 matching lines @@
 
   void hitTestChildren(HitTestResult result, { double x, double y }) {
     // defaultHitTestChildren(result, x: x, y: y);
   }
 
   void paint(RenderNodeDisplayList canvas) {
     super.paint(canvas);
     _layoutRoot.paint(canvas);
   }
 }