Remove custom elements examples, they are no longer maintained

sky/examples/stocks/stock.sky

Index: sky/examples/stocks/stock.sky
diff --git a/sky/examples/stocks/stock.sky b/sky/examples/stocks/stock.sky
deleted file mode 100644
index e4ace4cb5642f765b74dc04f0c7f9fc8c4b95aaa..0000000000000000000000000000000000000000
--- a/sky/examples/stocks/stock.sky
+++ /dev/null
@@ -1,72 +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/material-element.sky" />
-<import src="/sky/framework/elements/sky-element.sky" />
-<import src="stock-arrow.sky" />
-
-<sky-element>
-<template>
-  <style>
-  :host {
-    // TODO(eseidel): Why does setting height here make this too big?
-    // height: 48px;
-    max-height: 48px;
-    display: flex;
-    align-items: center;
-    border-bottom: 1px solid #F4F4F4;
-    padding-top: 16px;
-    padding-left: 16px;
-    padding-right: 16px;
-    padding-bottom: 20px;
-  }
-  stock-arrow {
-    margin-right: 16px;
-  }
-  #ticker {
-    flex: 1;
-    font-family: 'Roboto Medium', 'Helvetica';
-  }
-  #last-sale {
-    text-align: right;
-    padding-right: 16px;
-  }
-  #change {
-    color: #8A8A8A;
-    text-align: right;
-  }
-  </style>
-  <stock-arrow id="arrow" />
-  <div id="ticker" />
-  <div id="last-sale" />
-  <div id="change" />
-</template>
-<script>
-import "dart:sky";
-
-@Tagname('stock')
-class Stock extends MaterialElement {
-  var model; // model.Stock
-
-  void shadowRootReady() {
-    shadowRoot.getElementById('ticker').textContent = model.symbol;
-
-    Element lastSale = shadowRoot.getElementById('last-sale');
-    lastSale.textContent = "\$${model.lastSale.toStringAsFixed(2)}";
-
-    Element change = shadowRoot.getElementById('change');
-    String changeString = "${model.percentChange.toStringAsFixed(2)}%";
-    if (model.percentChange > 0)
-      changeString = "+" + changeString;
-    change.textContent = changeString;
-
-    StockArrow arrow = shadowRoot.getElementById('arrow');
-    arrow.change = model.percentChange;
-  }
-}
-
-_init(script) => register(script, Stock);
-</script>
-</sky-element>