Remove custom elements examples, they are no longer maintained

sky/examples/stocks/stock-arrow.sky

Index: sky/examples/stocks/stock-arrow.sky
diff --git a/sky/examples/stocks/stock-arrow.sky b/sky/examples/stocks/stock-arrow.sky
deleted file mode 100644
index 0f9b41321a98eb73d86ab24179ae68aee9600327..0000000000000000000000000000000000000000
--- a/sky/examples/stocks/stock-arrow.sky
+++ /dev/null
@@ -1,98 +0,0 @@
-<!--
-// 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 src="/sky/framework/elements/sky-element.sky" />
-
-<sky-element attributes="change:number">
-<template>
-  <style>
-  :host {
-    width: 40px;
-    height: 40px;
-    display: flex;
-    align-items: center;
-    justify-content: center;
-    border-radius: 40px;
-    border: 1px solid transparent;
-  }
-  #arrow {
-    width: 0;
-    height: 0;
-    border-left: 9px solid transparent;
-    border-right: 9px solid transparent;
-  }
-  .up {
-    margin-bottom: 3px;
-    border-bottom: 9px solid white;
-  }
-  .down {
-    margin-top: 3px;
-    border-top: 9px solid white;
-  }
-  </style>
-  <div id="arrow" />
-</template>
-<script>
-import "dart:sky";
-import "dart:math";
-
-final List<String> _kRedColors = [
-  '#E57373',
-  '#EF5350',
-  '#F44336',
-  '#E53935',
-  '#D32F2F',
-  '#C62828',
-  '#B71C1C',
-];
-
-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)];
-}
-
-@Tagname('stock-arrow')
-class StockArrow extends SkyElement {
-  Element _arrow;
-
-  void _updateArrow(double percentChange) {
-    String border = _colorForPercentChange(percentChange).toString();
-    String type = percentChange > 0 ? 'bottom' : 'top';
-    _arrow.style['border-$type-color'] = border;
-    style['border-color'] = border;
-    _arrow.setAttribute('class', percentChange > 0 ? 'up' : 'down');
-  }
-
-  void shadowRootReady() {
-    _arrow = shadowRoot.getElementById('arrow');
-    _updateArrow(change);
-  }
-
-  void changeChanged(double oldValue, double newValue) {
-    if (_arrow != null)
-      _updateArrow(newValue);
-  }
-}
-
-_init(script) => register(script, StockArrow);
-</script>
-</sky-element>