Teach stack to size to the max of its non-positioned children

sky/sdk/lib/framework/rendering/box.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:math' as math;
 import 'dart:sky' as sky;
 import 'object.dart';
 import '../painting/box_painter.dart';
 import 'package:vector_math/vector_math.dart';
 import 'package:sky/framework/net/image_cache.dart' as image_cache;
@@ skipping 384 matching lines @@
   }
 
   String debugDescribeSettings(String prefix) => '${super.debugDescribeSettings(prefix)}${prefix}additionalConstraints: ${additionalConstraints}\n';
 }
 
 class RenderShrinkWrapWidth extends RenderProxyBox {
   RenderShrinkWrapWidth({ RenderBox child }) : super(child);
 
   BoxConstraints _getInnerConstraints(BoxConstraints constraints) {
     double width = child.getMaxIntrinsicWidth(constraints);
+    if (width != constraints.constrainWidth(width)) {
+      print ("$width $constraints");
+    }
     assert(width == constraints.constrainWidth(width));
     return constraints.applyWidth(width);
   }
 
   double getMinIntrinsicWidth(BoxConstraints constraints) {
     if (child != null)
       return child.getMaxIntrinsicWidth(constraints);
     return constraints.constrainWidth(0.0);
   }
 
@@ skipping 534 matching lines @@
 
   void defaultPaint(RenderObjectDisplayList canvas) {
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is ParentDataType);
       canvas.paintChild(child, child.parentData.position);
       child = child.parentData.nextSibling;
     }
   }
 }