Fix logic in RenderPadding.

sky/sdk/lib/framework/rendering/block.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 'box.dart';
 import 'node.dart';
 
 class BlockParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> { }
 
 class RenderBlock extends RenderBox with ContainerRenderNodeMixin<RenderBox, BlockParentData>,
                                          RenderBoxContainerDefaultsMixin<RenderBox, BlockParentData> {
   // lays out RenderBox children in a vertical stack
   // uses the maximum width provided by the parent
   // sizes itself to the height of its child stack
 
+  RenderBlock({
+    List<RenderBox> children
+  }) {
+    if (children != null)
+      children.forEach((child) { add(child); });
+  }
+
   void setParentData(RenderBox child) {
     if (child.parentData is! BlockParentData)
       child.parentData = new BlockParentData();
   }
 
   // override this to report what dimensions you would have if you
   // were laid out with the given constraints this can walk the tree
   // if it must, but it should be as cheap as possible; just get the
   // dimensions and nothing else (e.g. don't calculate hypothetical
   // child positions if they're not needed to determine dimensions)
@@ skipping 33 matching lines @@
   void hitTestChildren(HitTestResult result, { sky.Point position }) {
     defaultHitTestChildren(result, position: position);
   }
 
   void paint(RenderNodeDisplayList canvas) {
     defaultPaint(canvas);
   }
 
 }