Fix theme changing: turns out we were not reparenting stateful surviving nodes when their parents c…

sky/sdk/lib/painting/box_painter.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:sky' show Point, Offset, Size, Rect, Color, Paint, Path;
 
 import 'shadows.dart';
 
 class BorderSide {
   const BorderSide({
     this.color: const Color(0xFF000000),
     this.width: 1.0
   });
@@ skipping 246 matching lines @@
       path = new Path();
       path.moveTo(rect.left, rect.bottom);
       path.lineTo(rect.left + _decoration.border.left.width, rect.bottom - _decoration.border.bottom.width);
       path.lineTo(rect.left + _decoration.border.left.width, rect.top + _decoration.border.top.width);
       path.lineTo(rect.left, rect.top);
       path.close();
       canvas.drawPath(path, paint);
     }
   }
 }