Move sky/examples to sky/sdk/lib/example, and code changes to support that change. Fixes T277.

sky/examples/rendering/justify_content.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';
-import 'dart:math' as math;
-
-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';
-
-import '../lib/solid_color_box.dart';
-
-// Attempts to draw
-// http://www.w3.org/TR/2015/WD-css-flexbox-1-20150514/images/flex-pack.svg
-void main() {
-  var table = new RenderFlex(direction: FlexDirection.vertical);
-
-  void addRow(FlexJustifyContent justify) {
-    RenderParagraph paragraph = new RenderParagraph(new InlineText("${justify}"));
-    table.add(new RenderPadding(child: paragraph, padding: new EdgeDims.only(top: 20.0)));
-    var row = new RenderFlex(direction: FlexDirection.horizontal);
-    row.add(new RenderSolidColorBox(const Color(0xFFFFCCCC), desiredSize: new Size(80.0, 60.0)));
-    row.add(new RenderSolidColorBox(const Color(0xFFCCFFCC), desiredSize: new Size(64.0, 60.0)));
-    row.add(new RenderSolidColorBox(const Color(0xFFCCCCFF), desiredSize: new Size(160.0, 60.0)));
-    row.justifyContent = justify;
-    table.add(row);
-    row.parentData.flex = 1;
-  }
-
-  addRow(FlexJustifyContent.flexStart);
-  addRow(FlexJustifyContent.flexEnd);
-  addRow(FlexJustifyContent.center);
-  addRow(FlexJustifyContent.spaceBetween);
-  addRow(FlexJustifyContent.spaceAround);
-
-  RenderDecoratedBox root = new RenderDecoratedBox(
-    decoration: new BoxDecoration(backgroundColor: const Color(0xFFFFFFFF)),
-    child: new RenderPadding(child: table, padding: new EdgeDims.symmetric(vertical: 50.0))
-  );
-
-  new SkyBinding(root: root);
-}