Add plugin or platform doesn't create www/plugins folder

Since the new Platform API polyfill, adding a platform or a plugin doesn't create the www/plugins folder, or copy the plugin/plugins there.

Repo adding a platform:

1. Create a new blank project
2. cordova plugin add cordova-plugin-camera
3. cordova platform add browser

Expected:

The platforms/browser/www folder contains a plugins folder that contains a cordova-plugin-camera folder.

Actual:

It doesn't.

Repo adding a plugin:

If you add the platform before the plugin, the same result occurs. Also, consider this scenario:

1. Create a new blank project
2. cordova platform add browser
3. cordova plugin add cordova-plugin-camera
4. cordova prepare
5. cordova plugin add cordova-plugin-device

Expected:

The platforms\browser\www\plugins folder should contain folders for cordova-plugin-camera and cordova-plugin-device.

Actual:

It only contains a folder for cordova-plugin-camera.