Split getIntrinsicDimensions into four pieces

sky/sdk/lib/framework/rendering/stack.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 'box.dart';
 import 'object.dart';
 
 class StackParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> { }
 
 class RenderStack extends RenderBox with ContainerRenderObjectMixin<RenderBox, StackParentData>,
                                          RenderBoxContainerDefaultsMixin<RenderBox, StackParentData> {
   RenderStack({
     List<RenderBox> children
   }) {
     if (children != null)
       children.forEach((child) { add(child); });
   }
 
   void setParentData(RenderBox child) {
     if (child.parentData is! StackParentData)
       child.parentData = new StackParentData();
   }
 
-  Size getIntrinsicDimensions(BoxConstraints constraints) {
-    return constraints.constrain(Size.infinite);
+  double getMinIntrinsicWidth(BoxConstraints constraints) {
+    return constraints.constrainWidth(double.INFINITY);
+  }
+
+  double getMaxIntrinsicWidth(BoxConstraints constraints) {
+    return constraints.constrainWidth(double.INFINITY);
+  }
+
+  double getMinIntrinsicHeight(BoxConstraints constraints) {
+    return constraints.constrainHeight(double.INFINITY);
+  }
+
+  double getMaxIntrinsicHeight(BoxConstraints constraints) {
+    return constraints.constrainHeight(double.INFINITY);
   }
 
   void performLayout() {
     size = constraints.constrain(Size.infinite);
     assert(size.width < double.INFINITY);
     assert(size.height < double.INFINITY);
     BoxConstraints innerConstraints = new BoxConstraints.loose(size);
 
     RenderBox child = firstChild;
     while (child != null) {
       child.layout(innerConstraints);
       assert(child.parentData is StackParentData);
       child.parentData.position = Point.origin;
       child = child.parentData.nextSibling;
     }
   }
 
   void hitTestChildren(HitTestResult result, { Point position }) {
     defaultHitTestChildren(result, position: position);
   }
 
   void paint(RenderObjectDisplayList canvas) {
     defaultPaint(canvas);
   }
 }