Remove "RenderBlock" class from examples that use it without giving it unrestricted height.

sky/sdk/example/rendering/baseline.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 'package:sky/painting/text_style.dart';
-import 'package:sky/rendering/block.dart';
 import 'package:sky/rendering/box.dart';
+import 'package:sky/rendering/flex.dart';
 import 'package:sky/rendering/object.dart';
 import 'package:sky/rendering/paragraph.dart';
 import 'package:sky/rendering/sky_binding.dart';
 
 RenderBox getBox(double lh) {
   RenderParagraph paragraph = new RenderParagraph(
     new InlineStyle(
       new TextStyle(
         color: const Color(0xFF0000A0)
       ),
@@ skipping 40 matching lines @@
               canvas.drawPath(path, paint);  
             }
           )
         )
       )
     )
   );
 }
 
 void main() {
-  RenderBox root = new RenderBlock(children: [
-    new RenderConstrainedBox(
-      additionalConstraints: new BoxConstraints.tightFor(height: 50.0)
-    ),
-    getBox(1.0),
-    getBox(null),
-  ]);
+  RenderBox root = new RenderFlex(children: [
+      new RenderConstrainedBox(
+        additionalConstraints: new BoxConstraints.tightFor(height: 50.0)
+      ),
+      getBox(1.0),
+      getBox(null),
+    ],
+    direction: FlexDirection.vertical,
+    alignItems: FlexAlignItems.stretch
+  );
   new SkyBinding(root: root);
 }