Heroku - 没有bower_components文件夹

我正在向Heroku部署一个Angular应用程序，我需要bower来添加Angular组件和其他一些组件 . 部署正在运行，除部署的站点之外的所有内容都缺少bower_components文件夹 . 我已经浏览了所有内容，并阅读了许多StackOverflow帖子，但我必须遗漏一些东西 . 这是我的代码：

的package.json

{
   "name": "my-webapp",
  "version": "1.0.0",
  "main": "app.js",
  "dependencies": {
    "bower": "^1.8.0",
    "express": "^4.15.2"
  },
  "devDependencies": {},
  "scripts": {
    "start": "node web.js",
    "postinstall": "./node_modules/bower/bin/bower install"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com...."
  },

  "author": "",
  "license": "ISC",
  "bugs": {
    "url": "https://github.com..."
  },
  "homepage": "https://github.com...",
  "description": ""
}

web.js

var express = require('express'),
app = express();

app.use(express.static(__dirname));
app.get('/', function(req, res) {
    res.sendfile('index.html', {root: __dirname })
});
var server = app.listen(process.env.PORT || 80);

Procfile

web: node web.js

bower.json

{
  "name": "my-webapp",
  "description": "",
  "main": "app.js",
  "authors": [
    "Me"
  ],
  "license": "ISC",
  "homepage": "https://my-webapp.herokuapp.com/",
  "ignore": [
    "**/.*",
    "node_modules",
    "bower_components",
    "test",
    "tests"
  ],
  "dependencies": {
    "angular-material-icons": "^0.7.1",
    "angular-material": "^1.1.1",
    "materialize": "^0.97.8",
    "ng-lodash": "^0.5.0"
  }

这是构建输出，编辑的亮点：

-----> Building dependencies
       Prebuild detected (node_modules already exists)
       Rebuilding any native modules
       bower@1.8.0 /tmp/build_9a163093ad395af381c984026f6a5742/me-my-webapp-bfae0f9/node_modules/bower
       express@4.15.2 /tmp/build_9a163093ad395af381c984026f6a5742/mugwag-my-webapp-bfae0f9/node_modules/express
-----> Caching build
       Clearing previous node cache
       Saving 2 cacheDirectories (default):
       - node_modules
       - bower_components
-----> Build succeeded!

-----> Rebuilding any native dependencies
       bower@1.8.0 /tmp/build_9a163093ad395af381c984026f6a5742/me-my-webapp-bfae0f9/node_modules/bower
       express@4.15.2 /tmp/build_9a163093ad395af381c984026f6a5742/me-my-webapp-bfae0f9/node_modules/express
????????? bower@1.8.0 
npm WARN my-webapp@1.0.0 No description
-----> Found bower.json, running bower install
-----> Installing dependencies

       > my-webapp@1.0.0 postinstall /tmp/build_9a163093ad395af381c984026f6a5742/me-my-webapp-bfae0f9
       > ./node_modules/bower/bin/bower install

       npm WARN my-webapp@1.0.0 No description

对我来说，它看起来好像一切正常，但是当我加载页面时，我得到了一大堆断开链接到bower_components文件夹，如下所示：

无法获取/bower_components/materialize/dist/css/materialize.css

没有凉亭文件夹 . 为什么！？