Remove outdated examples and framework pieces

sky/examples/file-browser.sky

-#!mojo mojo:sky_viewer
-<!--
-// Copyright 2014 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="../framework/sky-element/sky-element.sky" as="SkyElement" />
-<import src="../framework/xmlhttprequest.sky" as="XMLHttpRequest" />
-
-<sky-element name="file-browser">
-<template>
-  <style>
-    heading {
-      font-size: 16px;
-    }
-  </style>
-  <heading>File browser for {{ url }}</heading>
-  <template repeat="{{ directories }}">
-    <a href="{{}}">{{}}</a>
-  </template>
-  <template repeat="{{ files }}">
-    <a href="{{}}">{{}}</a>
-  </template>
-</template>
-<script>
-module.exports = class extends SkyElement {
-  created() {
-    this.url = '';
-    this.files = [];
-    this.directories = [];
-  }
-  attached() {
-    this.url = this.ownerDocument.URL;
-    var xhr = new XMLHttpRequest();
-    xhr.open('GET', this.url + '?format=json');
-    xhr.onload = (function() {
-      var listing = JSON.parse(xhr.responseText);
-      this.files = listing.files;
-      this.directories = listing.directories;
-    }).bind(this);
-    xhr.send();
-  }
-}.register();
-</script>
-</sky-element>