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

sky/examples/stocks/lib/stock_arrow.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:math';
-import 'package:sky/framework/fn.dart';
-import 'package:sky/framework/layout.dart';
-
-class StockArrow extends Component {
-  static final Style _style = new Style('''
-    width: 40px;
-    height: 40px;
-    align-items: center;
-    justify-content: center;
-    border-radius: 40px;
-    margin-right: 16px;
-    border: 1px solid transparent;'''
-  );
-
-  static final Style _upStyle = new Style('''
-    width: 0;
-    height: 0;
-    border-left: 9px solid transparent;
-    border-right: 9px solid transparent;
-    margin-bottom: 3px;
-    border-bottom: 9px solid white;'''
-  );
-
-  static final Style _downStyle = new Style('''
-    width: 0;
-    height: 0;
-    border-left: 9px solid transparent;
-    border-right: 9px solid transparent;
-    margin-top: 3px;
-    border-top: 9px solid white'''
-  );
-
-  double percentChange;
-
-  StockArrow({ Object key, this.percentChange }) : super(key: key);
-
-  // TODO(abarth): These should use sky/framework/theme/colors.dart.
-  final List<String> _kRedColors = [
-    '#E57373',
-    '#EF5350',
-    '#F44336',
-    '#E53935',
-    '#D32F2F',
-    '#C62828',
-    '#B71C1C',
-  ];
-
-  // TODO(abarth): These should use sky/framework/theme/colors.dart.
-  final List<String> _kGreenColors = [
-    '#81C784',
-    '#66BB6A',
-    '#4CAF50',
-    '#43A047',
-    '#388E3C',
-    '#2E7D32',
-    '#1B5E20',
-  ];
-
-  int _colorIndexForPercentChange(double percentChange) {
-    // Currently the max is 10%.
-    double maxPercent = 10.0;
-    return max(0, ((percentChange.abs() / maxPercent) * _kGreenColors.length).floor());
-  }
-
-  String _colorForPercentChange(double percentChange) {
-    if (percentChange > 0)
-      return _kGreenColors[_colorIndexForPercentChange(percentChange)];
-    return _kRedColors[_colorIndexForPercentChange(percentChange)];
-  }
-
-  UINode build() {
-    String border = _colorForPercentChange(percentChange).toString();
-    bool up = percentChange > 0;
-    String type = up ? 'bottom' : 'top';
-
-    return new FlexContainer(
-      inlineStyle: 'border-color: $border',
-      direction: FlexDirection.Row,
-      style: _style,
-      children: [
-        new Container(
-          inlineStyle: 'border-$type-color: $border',
-          style: up ? _upStyle : _downStyle
-        )
-      ]
-    );
-  }
-}