bower_components/bitcoinjs-lib/build dosen't exist

[coopci]

I added "bitcoinjs-lib": "~1.5.7" to bower.json, otherwise, even bower_components/bitcoinjs-lib dosen't exist.
Now my problem is there is no "build" subfolder under bower_components/bitcoinjs-lib:

# ls www/bower_components/bitcoinjs-lib/
LICENSE  package.json  README.md  src  test

I tried:

 browserify -r bitcoinjs-lib -s Bitcoin > bitcoinjs-lib.js

And copied the resulting bitcoinjs-lib.js to bower_components/bitcoinjs-lib/build, the Error: Bitcoin is undefined disappeared in browser, but more

HomeController/$scope.validate@http://54.169.233.199/js/controllers/landing/HomeController.js:17:9
functionCall/<@http://54.169.233.199/bower_components/angular/angular.js:10956:21
==@http://54.169.233.199/bower_components/angular/angular.js:10302:45
binaryFn/<@http://54.169.233.199/bower_components/angular/angular.js:10710:14
$digest@http://54.169.233.199/bower_components/angular/angular.js:12695:40
$apply@http://54.169.233.199/bower_components/angular/angular.js:12968:24
ngEventHandler/<@http://54.169.233.199/bower_components/angular/angular.js:19307:23
dispatch@http://54.169.233.199/bower_components/jquery/dist/jquery.min.js:4:8549
add/r.handle@http://54.169.233.199/bower_components/jquery/dist/jquery.min.js:4:5252

appeared in browser console.