Fix min/max typo in BoxConstraints.deflate

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 'dart:typed_data';
 import 'node.dart';
 import 'package:vector_math/vector_math.dart';
 
@@ skipping 37 matching lines @@
     : minWidth = size.width,
       maxWidth = size.width,
       minHeight = size.height,
       maxHeight = size.height;
 
   BoxConstraints deflate(EdgeDims edges) {
     assert(edges != null);
     double horizontal = edges.left + edges.right;
     double vertical = edges.top + edges.bottom;
     return new BoxConstraints(
-      minWidth: math.min(0.0, minWidth - horizontal),
+      minWidth: math.max(0.0, minWidth - horizontal),
       maxWidth: maxWidth - horizontal,
-      minHeight: math.min(0.0, minHeight - vertical),
+      minHeight: math.max(0.0, minHeight - vertical),
       maxHeight: maxHeight - vertical
     );
   }
 
   final double minWidth;
   final double maxWidth;
   final double minHeight;
   final double maxHeight;
 
   double constrainWidth(double width) {
@@ skipping 390 matching lines @@
 
   void defaultPaint(RenderNodeDisplayList canvas) {
     RenderBox child = firstChild;
     while (child != null) {
       assert(child.parentData is ParentDataType);
       canvas.paintChild(child, child.parentData.position);
       child = child.parentData.nextSibling;
     }
   }
 }