Give the popup menu a 2px border radius

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 'object.dart';
 import 'package:vector_math/vector_math.dart';
 import 'package:sky/framework/net/image_cache.dart' as image_cache;
@@ skipping 631 matching lines @@
   final double blur;
 
   String toString() => 'BoxShadow($color, $offset, $blur)';
 }
 
 // This must be immutable, because we won't notice when it changes
 class BoxDecoration {
   const BoxDecoration({
     this.backgroundColor,
     this.border,
+    this.borderRadius,
     this.boxShadow
   });
 
   final Color backgroundColor;
+  final double borderRadius;
   final Border border;
   final List<BoxShadow> boxShadow;
 
   String toString([String prefix = '']) {
     List<String> result = [];
     if (backgroundColor != null)
       result.add('${prefix}backgroundColor: $backgroundColor');
     if (border != null)
       result.add('${prefix}border: $border');
-    if (boxShadow != null) {
-      for (BoxShadow shadow in boxShadow)
-        result.add('${prefix}boxShadow: $shadow');
-    }
+    if (borderRadius != null)
+      result.add('${prefix}borderRadius: $borderRadius');
+    if (boxShadow != null)
+      result.add('${prefix}boxShadow: ${boxShadow.map((shadow) => shadow.toString())}');
     if (result.isEmpty)
       return '${prefix}<no decorations specified>';
     return result.join('\n');
   }
 }
 
 class RenderDecoratedBox extends RenderProxyBox {
 
   RenderDecoratedBox({
     BoxDecoration decoration,
@@ skipping 44 matching lines @@
       _cachedBackgroundPaint = paint;
     }
 
     return _cachedBackgroundPaint;
   }
 
   void paint(RenderObjectDisplayList canvas) {
     assert(size.width != null);
     assert(size.height != null);
 
-    if (_decoration.backgroundColor != null || _decoration.boxShadow != null)
-      canvas.drawRect(new Rect.fromLTRB(0.0, 0.0, size.width, size.height), _backgroundPaint);
+    if (_decoration.backgroundColor != null || _decoration.boxShadow != null) {
+      Rect rect = new Rect.fromLTRB(0.0, 0.0, size.width, size.height);
+      if (_decoration.borderRadius == null)
+        canvas.drawRect(rect, _backgroundPaint);
+      else
+        canvas.drawRRect(new sky.RRect()..setRectXY(rect, _decoration.borderRadius, _decoration.borderRadius), _backgroundPaint);
+    }
 
     if (_decoration.border != null) {
+      assert(_decoration.borderRadius == null); // TODO(abarth): Implement borders with border radius.
+
       assert(_decoration.border.top != null);
       assert(_decoration.border.right != null);
       assert(_decoration.border.bottom != null);
       assert(_decoration.border.left != null);
 
       Paint paint = new Paint();
       Path path;
 
       paint.color = _decoration.border.top.color;
       path = new Path();
@@ skipping 262 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;
     }
   }
 }