Fix test failures from b9e2a7fd2bb21933c4dd23354a35a2d83bdc3be8

sky/sdk/lib/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:math' as math;
 
 import 'box.dart';
 import 'object.dart';
 
 class BlockParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> { }
 
 abstract class RenderBlockBase extends RenderBox with ContainerRenderObjectMixin<RenderBox, BlockParentData>,
                                                       RenderBoxContainerDefaultsMixin<RenderBox, BlockParentData> {
 
   // lays out RenderBox children in a vertical stack
   // uses the maximum width provided by the parent
 
-  bool _hasVisualOverflow = false;
-
   RenderBlockBase({
     List<RenderBox> children
   }) {
     addAll(children);
   }
 
   void setupParentData(RenderBox child) {
     if (child.parentData is! BlockParentData)
       child.parentData = new BlockParentData();
   }
@@ skipping 86 matching lines @@
   }
 
 }
 
 class RenderBlock extends RenderBlockBase {
 
   // sizes itself to the height of its child stack
 
   RenderBlock({ List<RenderBox> children }) : super(children: children);
 
+  bool _hasVisualOverflow = false;
+
   void performLayout() {
     super.performLayout();
+    size = constraints.constrain(new Size(constraints.maxWidth, childrenHeight));
+    assert(!size.isInfinite);
+
     // FIXME(eseidel): Block lays out its children with unconstrained height
     // yet itself remains constrained. Remember that our children wanted to
     // be taller than we are so we know to clip them (and not cause confusing
     // mismatch of painting vs. hittesting).
     _hasVisualOverflow = childrenHeight > size.height;
-    size = constraints.constrain(new Size(constraints.maxWidth, childrenHeight));
-    assert(!size.isInfinite);
   }
 
   void paint(PaintingCanvas canvas, Offset offset) {
     if (_hasVisualOverflow) {
       canvas.save();
       canvas.clipRect(offset & size);
     }
     super.paint(canvas, offset);
     if (_hasVisualOverflow) {
       canvas.restore();
     }
   }
 
 }
-