Rename BlockContainer, StackContainer, and FlexContainer

sky/examples/stocks2/lib/stock_row.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/framework/components2/ink_well.dart';
 import 'package:sky/framework/fn2.dart';
 import 'package:sky/framework/rendering/flex.dart';
 import 'package:sky/framework/rendering/box.dart';
 import 'package:sky/framework/theme/typography.dart' as typography;
@@ skipping 26 matching lines @@
     ];
 
     // TODO(hansmuller): An explicit |height| shouldn't be needed
     return new InkWell(children: [
       new Container(
         padding: const EdgeDims(16.0, 16.0, 20.0, 16.0),
         height: kHeight,
         decoration: const BoxDecoration(
             border: const Border(
                 bottom: const BorderSide(color: const sky.Color(0xFFF4F4F4)))),
-        child: new FlexContainer(children: children)
+        child: new Flex(children)
       )
     ]);
   }
 }