Make Drawer in components2 work

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 'dart:sky' as sky;
+import 'box.dart';
+import 'node.dart';
+
+class StackParentData extends BoxParentData with ContainerParentDataMixin<RenderBox> { }
+
+class RenderStack extends RenderBox with ContainerRenderNodeMixin<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();
+  }
+
+  sky.Size getIntrinsicDimensions(BoxConstraints constraints) {
+    return constraints.constrain(new sky.Size.infinite());
+  }
+
+  void performLayout() {
+    size = constraints.constrain(new sky.Size.infinite());
+    assert(size.width < double.INFINITY);
+    assert(size.height < double.INFINITY);
+    BoxConstraints innerConstraints = new BoxConstraints.loose(size);
+
+    sky.Point origin = new sky.Point(0.0, 0.0);
+    RenderBox child = firstChild;
+    while (child != null) {
+      child.layout(innerConstraints);
+      assert(child.parentData is StackParentData);
+      child.parentData.position = origin;
+      child = child.parentData.nextSibling;
+    }
+  }
+
+  void hitTestChildren(HitTestResult result, { sky.Point position }) {
+    defaultHitTestChildren(result, position: position);
+  }
+
+  void paint(RenderNodeDisplayList canvas) {
+    defaultPaint(canvas);
+  }
+}